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  • Question 1 - A 45-year-old female is admitted to the hospital for investigation of recently developed...

    Incorrect

    • A 45-year-old female is admitted to the hospital for investigation of recently developed hypertension, myalgia, and a facial rash. She experiences a decline in kidney function and complains of muscle aches and ankle swelling during her hospital stay. A kidney biopsy and urine sample are taken, revealing a proliferative 'wire-loop' glomerular lesion on histopathological assessment. The urinalysis shows proteinuria but no presence of leukocytes or nitrites. What is the most probable diagnosis?

      Your Answer: IgA nephropathy

      Correct Answer: Systemic lupus erythematosus

      Explanation:

      Lupus nephritis is characterized by proliferative ‘wire-loop’ glomerular histology, proteinuria, and systemic symptoms. This condition occurs when autoimmune processes in SLE cause inflammation and damage to the glomeruli. Symptoms may include oedema, myalgia, arthralgia, hypertension, and foamy-appearing urine due to high levels of protein. Acute tubular necrosis primarily affects the tubules and does not typically present with proteinuria. Congestive heart failure and IgA nephropathy can cause proteinuria, but they do not result in the ‘wire-loop’ glomerular lesion seen in lupus nephritis. Pyelonephritis may also cause proteinuria, but it is an infectious process and would present with additional symptoms such as nitrites, leukocytes, and blood in the urine.

      Renal Complications in Systemic Lupus Erythematosus

      Systemic lupus erythematosus (SLE) can lead to severe renal complications, including lupus nephritis, which can result in end-stage renal disease. Regular check-ups with urinalysis are necessary to detect proteinuria in SLE patients. The WHO classification system categorizes lupus nephritis into six classes, with class IV being the most common and severe form. Renal biopsy shows characteristic findings such as endothelial and mesangial proliferation, a wire-loop appearance, and subendothelial immune complex deposits.

      Management of lupus nephritis involves treating hypertension and using glucocorticoids with either mycophenolate or cyclophosphamide for initial therapy in cases of focal (class III) or diffuse (class IV) lupus nephritis. Mycophenolate is generally preferred over azathioprine for subsequent therapy to decrease the risk of developing end-stage renal disease. Early detection and proper management of renal complications in SLE patients are crucial to prevent irreversible damage to the kidneys.

    • This question is part of the following fields:

      • Renal System
      27.6
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  • Question 2 - A 45-year-old patient presents to the clinic with complaints of abdominal pain. Upon...

    Incorrect

    • A 45-year-old patient presents to the clinic with complaints of abdominal pain. Upon routine blood tests, the following results were obtained:

      Na+ 142 mmol/l
      K+ 4.0 mmol/l
      Chloride 104 mmol/l
      Bicarbonate 19 mmol/l
      Urea 7.0 mmol/l
      Creatinine 112 µmol/l

      What is the calculated anion gap?

      Your Answer: 4 mmol/L

      Correct Answer: 23 mmol/L

      Explanation:

      Understanding Anion Gap in Metabolic Acidosis

      Metabolic acidosis is a condition where the body produces too much acid or loses too much bicarbonate. Anion gap is a useful tool in diagnosing metabolic acidosis. It is calculated by subtracting the sum of bicarbonate and chloride from the sum of sodium and potassium. A normal anion gap is between 8-14 mmol/L.

      There are two types of metabolic acidosis: normal anion gap and raised anion gap. Normal anion gap or hyperchloraemic metabolic acidosis can be caused by gastrointestinal bicarbonate loss, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis can be caused by lactate due to shock or hypoxia, ketones in diabetic ketoacidosis or alcohol, urate in renal failure, acid poisoning from salicylates or methanol, and 5-oxoproline from chronic paracetamol use.

      Understanding anion gap in metabolic acidosis is crucial in identifying the underlying cause of the condition. It helps healthcare professionals in providing appropriate treatment and management to patients.

    • This question is part of the following fields:

      • Renal System
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  • Question 3 - A woman presents with symptoms of agalactorrhoea, amenorrhoea, intolerance to cold, constipation, and...

    Incorrect

    • A woman presents with symptoms of agalactorrhoea, amenorrhoea, intolerance to cold, constipation, and weight loss six months after giving birth. She experienced postpartum bleeding during delivery and has now been diagnosed with hypopituitarism. What could be the possible reason for this condition?

      Your Answer: Autoimmune hypophysitis

      Correct Answer: Sheehan's syndrome

      Explanation:

      Sheehan’s syndrome is a condition that arises from pituitary ischaemia, which is caused by blood loss during or after childbirth. The syndrome is characterized by symptoms that indicate global hypopituitarism, including agalactorrhoea (lack of prolactin), amenorrhoea (lack of FSH and LH), cold intolerance and constipation (lack of thyroid hormones), and weight loss (lack of steroid hormones).

      Malignancy is an uncommon cause of hypopituitarism.

      While pituitary adenoma is a frequent cause of hypopituitarism, it is unlikely to be the cause of this patient’s symptoms, given that they occurred after childbirth. Pituitary adenoma may also present with symptoms related to mass effect, such as headache and bilateral hemianopia.

      Understanding Hypopituitarism: Causes, Symptoms, and Management

      Hypopituitarism is a medical condition that occurs when the pituitary gland fails to produce enough hormones. This can be caused by various factors such as compression of the gland by non-secretory pituitary macroadenoma, pituitary apoplexy, Sheehan’s syndrome, hypothalamic tumors, trauma, iatrogenic irradiation, and infiltrative diseases like hemochromatosis and sarcoidosis. The symptoms of hypopituitarism depend on which hormones are deficient. For instance, low ACTH can cause tiredness and postural hypotension, while low FSH/LH can lead to amenorrhea, infertility, and loss of libido. Low TSH can cause constipation and feeling cold, while low GH can result in short stature if it occurs during childhood. Low prolactin can cause problems with lactation.

      To diagnose hypopituitarism, hormone profile testing and imaging are usually conducted. Treatment involves addressing the underlying cause, such as surgical removal of pituitary macroadenoma, and replacement of deficient hormones. It is important to manage hypopituitarism promptly to prevent complications and improve the patient’s quality of life.

    • This question is part of the following fields:

      • Renal System
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  • Question 4 - A 50-year-old male is brought back to a surgical ward after a renal...

    Incorrect

    • A 50-year-old male is brought back to a surgical ward after a renal transplant. Diuresis suddenly decreases 2 hours after the transplantation. The patient is quickly transferred back to surgery where the transplanted kidney displays signs of hyperacute rejection and is removed. Histopathological examination confirms hyperacute rejection.

      What type of reaction has this patient undergone?

      Your Answer: Type I hypersensitivity

      Correct Answer: Type II hypersensitivity

      Explanation:

      Hyperacute transplant rejection is a type II hypersensitivity reaction, which is characterized by a cytotoxic response caused by pre-existing antibodies to the ABO or HLA antigens. This reaction leads to widespread thrombosis and ischaemia/necrosis within the transplanted organ, necessitating its surgical removal.

      In contrast, type I hypersensitivity is an immediate IgE-mediated reaction that occurs within minutes, while type III hypersensitivity is an IgM-mediated reaction that involves the formation of circulating immune complexes. Type IV hypersensitivity is a cell-mediated response that takes weeks to develop and is seen in chronic graft rejections. Finally, type V hypersensitivity is an autoimmune reaction that involves the binding of auto-antibodies to cell surface receptors, either preventing the intended ligand binding or mimicking its effects.

      The HLA system, also known as the major histocompatibility complex (MHC), is located on chromosome 6 and is responsible for human leucocyte antigens. Class 1 antigens include A, B, and C, while class 2 antigens include DP, DQ, and DR. When matching for a renal transplant, the importance of HLA antigens is ranked as DR > B > A.

      Graft survival rates for renal transplants are high, with a 90% survival rate at one year and a 60% survival rate at ten years for cadaveric transplants. Living-donor transplants have even higher survival rates, with a 95% survival rate at one year and a 70% survival rate at ten years. However, postoperative problems can occur, such as acute tubular necrosis of the graft, vascular thrombosis, urine leakage, and urinary tract infections.

      Hyperacute rejection can occur within minutes to hours after a transplant and is caused by pre-existing antibodies against ABO or HLA antigens. This type of rejection is an example of a type II hypersensitivity reaction and leads to widespread thrombosis of graft vessels, resulting in ischemia and necrosis of the transplanted organ. Unfortunately, there is no treatment available for hyperacute rejection, and the graft must be removed.

      Acute graft failure, which occurs within six months of a transplant, is usually due to mismatched HLA and is caused by cell-mediated cytotoxic T cells. This type of failure is usually asymptomatic and is detected by a rising creatinine, pyuria, and proteinuria. Other causes of acute graft failure include cytomegalovirus infection, but it may be reversible with steroids and immunosuppressants.

      Chronic graft failure, which occurs after six months of a transplant, is caused by both antibody and cell-mediated mechanisms that lead to fibrosis of the transplanted kidney, known as chronic allograft nephropathy. The recurrence of the original renal disease, such as MCGN, IgA, or FSGS, can also cause chronic graft failure.

    • This question is part of the following fields:

      • Renal System
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  • Question 5 - A 44-year-old woman presents to the emergency department with abdominal pain. She reports...

    Incorrect

    • A 44-year-old woman presents to the emergency department with abdominal pain. She reports feeling generally unwell for the last 2 days but says today is the worst she has felt.

      On examination, her heart rate is 110 beats/min with a blood pressure of 106/70mmHg and a respiratory rate of 27 breaths/min.

      An arterial blood gas is taken:

      pH 7.11 (7.35 - 7.45)
      pO2 11.2 kPa (10.5 - 13.5)
      pCO2 4.9 kPa (4.7 - 6.0)
      Sodium 142 mmol/L (135 - 145)
      Potassium 5.1 mmol/L (3.5 - 5.5)
      Chloride 111 mmol/L (96 - 106)
      Bicarbonate 17 mmol/L (22 - 28)
      Lactate 2.6 mmol/L (0.6 - 1.9)
      Glucose 10.5 mmol/L (4 - 7)

      What is the most likely cause for this patient's investigation findings?

      Your Answer: Diabetic ketoacidosis

      Correct Answer: Diarrhoea

      Explanation:

      The patient’s condition is caused by diarrhoea, which is a common cause of normal anion gap metabolic acidosis. The anion gap is calculated by subtracting the sum of chloride and bicarbonate levels from the sum of sodium and potassium levels. In this case, the anion gap is within the normal range of 10-18 mmol/L. Other causes of normal anion gap metabolic acidosis include ureterosigmoidostomy, renal tubular acidosis, Addison’s disease, and certain medications. Raised anion gap metabolic acidosis can be remembered using the mnemonic ‘MUDPILES’, which includes causes such as methanol poisoning, diabetic ketoacidosis, and salicylate poisoning. However, these are not relevant in this case as the patient has a normal anion gap metabolic acidosis caused by diarrhoea.

      Understanding Metabolic Acidosis

      Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.

      Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.

      Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.

    • This question is part of the following fields:

      • Renal System
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  • Question 6 - A 55-year-old man with a medical history of ischaemic heart disease, gout, and...

    Correct

    • A 55-year-old man with a medical history of ischaemic heart disease, gout, and diabetes presents with sudden and severe pain in his left renal angle that radiates to his groin. Upon undergoing an urgent CT KUB, it is confirmed that he has nephrolithiasis with hydronephrosis. As a result, he is admitted under the urology team for immediate intervention due to acute kidney injury.

      What is the most common material that makes up these calculi in the general population?

      Your Answer: Calcium oxalate

      Explanation:

      Renal stones can be classified into different types based on their composition. Calcium oxalate stones are the most common, accounting for 85% of all calculi. These stones are formed due to hypercalciuria, hyperoxaluria, and hypocitraturia. They are radio-opaque and may also bind with uric acid stones. Cystine stones are rare and occur due to an inherited recessive disorder of transmembrane cystine transport. Uric acid stones are formed due to purine metabolism and may precipitate when urinary pH is low. Calcium phosphate stones are associated with renal tubular acidosis and high urinary pH. Struvite stones are formed from magnesium, ammonium, and phosphate and are associated with chronic infections. The pH of urine can help determine the type of stone present, with calcium phosphate stones forming in normal to alkaline urine, uric acid stones forming in acidic urine, and struvate stones forming in alkaline urine. Cystine stones form in normal urine pH.

    • This question is part of the following fields:

      • Renal System
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  • Question 7 - Which one of the following decreases the production of renin? ...

    Correct

    • Which one of the following decreases the production of renin?

      Your Answer: Beta-blockers

      Explanation:

      Renin and its Factors

      Renin is a hormone that is produced by juxtaglomerular cells. Its main function is to convert angiotensinogen into angiotensin I. There are several factors that can stimulate or reduce the secretion of renin.

      Factors that stimulate renin secretion include hypotension, which can cause reduced renal perfusion, hyponatremia, sympathetic nerve stimulation, catecholamines, and erect posture. On the other hand, there are also factors that can reduce renin secretion, such as beta-blockers and NSAIDs.

      It is important to understand the factors that affect renin secretion as it plays a crucial role in regulating blood pressure and fluid balance in the body. By knowing these factors, healthcare professionals can better manage and treat conditions related to renin secretion.

    • This question is part of the following fields:

      • Renal System
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  • Question 8 - A 44-year-old man presents with a three-week history of leg swelling. He has...

    Incorrect

    • A 44-year-old man presents with a three-week history of leg swelling. He has no past medical history except for a bout of sore throat at the age of 15. He is not on any medications. On examination, his blood pressure is 155/94 mmHg, and he has pitting edema. Urinalysis reveals 4+ protein with no RBC casts. A biopsy confirms the diagnosis of membranous glomerulonephritis.

      What is the most probable cause of this patient's condition?

      Your Answer: Hypertension

      Correct Answer: Anti-phospholipase A2 antibodies

      Explanation:

      The likely diagnosis for this patient is idiopathic membranous glomerulonephritis, which is associated with anti-phospholipase A2 antibodies. While hypertension may be present in patients with nephrotic syndrome, it is not the cause of membranous glomerulonephritis. Secondary causes of membranous glomerulonephritis include malignancy (such as lung cancer, lymphoma, or leukemia) and systemic lupus erythematosus, but there are no indications of these in this patient. Sore throat is associated with post-streptococcal glomerulonephritis and IgA nephropathy, but these are not relevant to this case.

      Membranous glomerulonephritis is the most common type of glomerulonephritis in adults and is the third leading cause of end-stage renal failure. It typically presents with proteinuria or nephrotic syndrome. A renal biopsy will show a thickened basement membrane with subepithelial electron dense deposits, creating a spike and dome appearance. The condition can be caused by various factors, including infections, malignancy, drugs, autoimmune diseases, and idiopathic reasons.

      Management of membranous glomerulonephritis involves the use of ACE inhibitors or ARBs to reduce proteinuria and improve prognosis. Immunosuppression may be necessary for patients with severe or progressive disease, but many patients spontaneously improve. Corticosteroids alone are not effective, and a combination of corticosteroid and another agent such as cyclophosphamide is often used. Anticoagulation may be considered for high-risk patients.

      The prognosis for membranous glomerulonephritis follows the rule of thirds: one-third of patients experience spontaneous remission, one-third remain proteinuric, and one-third develop end-stage renal failure. Good prognostic factors include female sex, young age at presentation, and asymptomatic proteinuria of a modest degree at the time of diagnosis.

    • This question is part of the following fields:

      • Renal System
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  • Question 9 - A 45-year-old man presents to the physician complaining of fatigue, dark urine, and...

    Correct

    • A 45-year-old man presents to the physician complaining of fatigue, dark urine, and swelling in his lower extremities that has been ongoing for the past two weeks. He has no significant medical history and is not taking any medications. He denies using tobacco, alcohol, or drugs. During the physical examination, symmetric pitting oedema is observed in his lower extremities, and his blood pressure is 132/83 mmHg with a pulse of 84/min.

      Laboratory results reveal a urea level of 4mmol/L (2.0 - 7.0) and a creatinine level of 83 µmol/L (55 - 120). Urinalysis shows 4+ proteinuria and microscopic hematuria. Electron microscopy of the kidney biopsy specimen reveals dense deposits within the glomerular basement membrane, and immunofluorescence microscopy is positive for C3, not immunoglobulins.

      What is the most likely pathophysiologic mechanism underlying this patient's condition?

      Your Answer: Persistent activation of alternate complement pathway

      Explanation:

      The cause of membranoproliferative glomerulonephritis, type 2, is persistent activation of the alternative complement pathway, which leads to kidney damage. This condition is characterized by IgG antibodies, known as C3 nephritic factor, that target C3 convertase. In contrast, Goodpasture’s syndrome is associated with anti-GBM antibodies, while rapidly progressive glomerulonephritis may involve cell-mediated injury. Immune complex-mediated glomerulopathies, such as SLE and post-streptococcal glomerulonephritis, are caused by circulating immune complexes, while non-immunologic kidney damage is seen in diabetic nephropathy and hypertensive nephropathy.

      Understanding Membranoproliferative Glomerulonephritis

      Membranoproliferative glomerulonephritis, also known as mesangiocapillary glomerulonephritis, is a kidney disease that can present as nephrotic syndrome, haematuria, or proteinuria. Unfortunately, it has a poor prognosis. There are three types of this disease, with type 1 accounting for 90% of cases. It is caused by cryoglobulinaemia and hepatitis C, and can be diagnosed through a renal biopsy that shows subendothelial and mesangium immune deposits of electron-dense material resulting in a ‘tram-track’ appearance under electron microscopy.

      Type 2, also known as ‘dense deposit disease’, is caused by partial lipodystrophy and factor H deficiency. It is characterized by persistent activation of the alternative complement pathway, low circulating levels of C3, and the presence of C3b nephritic factor in 70% of cases. This factor is an antibody to alternative-pathway C3 convertase (C3bBb) that stabilizes C3 convertase. A renal biopsy for type 2 shows intramembranous immune complex deposits with ‘dense deposits’ under electron microscopy.

      Type 3 is caused by hepatitis B and C. While steroids may be effective in managing this disease, it is important to note that the prognosis for all types of membranoproliferative glomerulonephritis is poor. Understanding the different types and their causes can help with diagnosis and management of this serious kidney disease.

    • This question is part of the following fields:

      • Renal System
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  • Question 10 - What is measured to obtain renal plasma flow if the patient is a...

    Incorrect

    • What is measured to obtain renal plasma flow if the patient is a few years older?

      Your Answer: Creatinine

      Correct Answer: Para-amino hippuric acid (PAH)

      Explanation:

      The normal value for renal plasma flow is 660ml/min, which is calculated by dividing the amount of PAH in urine per unit time by the difference in PAH concentration in the renal artery or vein.

      The Loop of Henle and its Role in Renal Physiology

      The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.

    • This question is part of the following fields:

      • Renal System
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  • Question 11 - A 64-year-old man is seen in the endocrinology clinic for review of his...

    Correct

    • A 64-year-old man is seen in the endocrinology clinic for review of his type II diabetes. He is currently on metformin and gliclazide, but his HbA1c is 68 mmol/mol. To improve his glycaemic control, you plan to initiate empagliflozin as a third agent. What is the site of action of this medication to achieve its mechanism of action?

      Your Answer: Proximal convoluted tubule of the nephron

      Explanation:

      The proximal convoluted tubule of the nephron is where the majority of glucose reabsorption occurs. Empagliflozin, which inhibits the SGLT-2 receptor, prevents glucose reabsorption in this area. Insulin receptors are found throughout the body, not SGLT-2 receptors. The distal convoluted tubule regulates sodium, potassium, calcium, and pH, while the loop of Henle is involved in water resorption. Sulphonylureas act on pancreatic beta cells to increase insulin production and improve glucose metabolism.

      The Loop of Henle and its Role in Renal Physiology

      The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.

    • This question is part of the following fields:

      • Renal System
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  • Question 12 - A 55-year-old male presents to the emergency department with a high fever and...

    Incorrect

    • A 55-year-old male presents to the emergency department with a high fever and fatigue. He does not have any history to offer. On examination, he is noted to have splinter haemorrhages and conjunctival pallor. His observations show him to be pyrexial at 39°C. A pansystolic murmur is audible throughout the praecordium, and an echocardiogram reveals vegetations. He is diagnosed with infective endocarditis and initiated on a triple antibiotic therapy of gentamicin, vancomycin and amoxicillin. The following U&E results are noted at admission:

      Na+ 140 mmol/L (135 - 145)
      K+ 4.0 mmol/L (3.5 - 5.0)
      Bicarbonate 25 mmol/L (22 - 29)
      Urea 4.0 mmol/L (2.0 - 7.0)
      Creatinine 75 µmol/L (55 - 120)

      However, following three days of inpatient treatment, the patient becomes anuric. A repeat set of U&Es reveal the following:

      Na+ 145 mmol/L (135 - 145)
      K+ 5.0 mmol/L (3.5 - 5.0)
      Bicarbonate 25 mmol/L (22 - 29)
      Urea 12.0 mmol/L (2.0 - 7.0)
      Creatinine 150 µmol/L (55 - 120)

      What is the likely mechanism of gentamicin causing this patient’s kidney injury?

      Your Answer: Post-renal obstruction

      Correct Answer: Renal cell apoptosis

      Explanation:

      AKI can be attributed to gentamicin due to its ability to induce apoptosis in renal cells. Therefore, patients who are prescribed gentamicin should undergo frequent monitoring of their renal function and drug concentration levels. While there are other potential causes of acute kidney injury, none of them are linked to aminoglycoside antibiotics.

      Understanding the Difference between Acute Tubular Necrosis and Prerenal Uraemia

      Acute kidney injury can be caused by various factors, including prerenal uraemia and acute tubular necrosis. It is important to differentiate between the two to determine the appropriate treatment. Prerenal uraemia occurs when the kidneys hold on to sodium to preserve volume, leading to decreased blood flow to the kidneys. On the other hand, acute tubular necrosis is caused by damage to the kidney tubules, which can be due to various factors such as toxins, infections, or ischemia.

      To differentiate between the two, several factors can be considered. In prerenal uraemia, the urine sodium level is typically less than 20 mmol/L, while in acute tubular necrosis, it is usually greater than 40 mmol/L. The urine osmolality is also higher in prerenal uraemia, typically above 500 mOsm/kg, while in acute tubular necrosis, it is usually below 350 mOsm/kg. The fractional sodium excretion is less than 1% in prerenal uraemia, while it is greater than 1% in acute tubular necrosis. Additionally, the response to fluid challenge is typically good in prerenal uraemia, while it is poor in acute tubular necrosis.

      Other factors that can help differentiate between the two include the serum urea:creatinine ratio, fractional urea excretion, urine:plasma osmolality, urine:plasma urea, specific gravity, and urine sediment. By considering these factors, healthcare professionals can accurately diagnose and treat acute kidney injury.

    • This question is part of the following fields:

      • Renal System
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  • Question 13 - A 58-year-old man has had a radical nephrectomy. Upon bisecting the kidney, the...

    Incorrect

    • A 58-year-old man has had a radical nephrectomy. Upon bisecting the kidney, the pathologist observes a pink fleshy tumor in the renal pelvis. What is the probable illness?

      Your Answer: Renal cell carcinoma

      Correct Answer: Transitional cell carcinoma

      Explanation:

      Renal tumours typically have a yellow or brown hue, but TCCs stand out as they have a pink appearance. If a TCC is detected in the renal pelvis, a nephroureterectomy is necessary.

      Renal Lesions: Types, Features, and Treatments

      Renal lesions refer to abnormal growths or masses that develop in the kidneys. There are different types of renal lesions, each with its own disease-specific features and treatment options. Renal cell carcinoma is the most common renal tumor, accounting for 85% of cases. It often presents with haematuria and may cause hypertension and polycythaemia as paraneoplastic features. Treatment usually involves radical or partial nephrectomy.

      Nephroblastoma, also known as Wilms tumor, is a rare childhood tumor that accounts for 80% of all genitourinary malignancies in those under the age of 15 years. It often presents with a mass and hypertension. Diagnostic workup includes ultrasound and CT scanning, and treatment involves surgical resection combined with chemotherapy. Neuroblastoma is the most common extracranial tumor of childhood, with up to 80% occurring in those under 4 years of age. It is a tumor of neural crest origin and may be diagnosed using MIBG scanning. Treatment involves surgical resection, radiotherapy, and chemotherapy.

      Transitional cell carcinoma accounts for 90% of lower urinary tract tumors but only 10% of renal tumors. It often presents with painless haematuria and may be caused by occupational exposure to industrial dyes and rubber chemicals. Diagnosis and staging are done with CT IVU, and treatment involves radical nephroureterectomy. Angiomyolipoma is a hamartoma type lesion that occurs sporadically in 80% of cases and in those with tuberous sclerosis in the remaining cases. It is composed of blood vessels, smooth muscle, and fat and may cause massive bleeding in 10% of cases. Surgical resection is required for lesions larger than 4 cm and causing symptoms.

    • This question is part of the following fields:

      • Renal System
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  • Question 14 - A 32-year-old construction worker becomes dehydrated after spending the day working under the...

    Incorrect

    • A 32-year-old construction worker becomes dehydrated after spending the day working under the sun.

      What can be inferred about this person?

      Your Answer: Decreased secretion of vasopressin from the pituitary gland

      Correct Answer: Most of the ultrafiltrated water in the nephron to be reabsorbed in the proximal tubule

      Explanation:

      The majority of filtered water is absorbed in the proximal tubule, while the highest amount of sodium reabsorption occurs in this area due to the Na+/K+ ATPase mechanism. This results in the movement of fluid from the proximal tubules to peritubular capillaries.

      After a strenuous run, the individual is likely to be slightly dehydrated, leading to an increased activation of the renin-angiotensin-aldosterone system. This would cause an increase in aldosterone release from the zona glomerulosa. Additionally, vasopressin (also known as ADH) would be elevated to enhance water reabsorption in the collecting duct.

      Renal cortical blood flow is higher than medullary blood flow, as tubular cells are more susceptible to ischaemia.

      The Loop of Henle and its Role in Renal Physiology

      The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.

    • This question is part of the following fields:

      • Renal System
      28
      Seconds
  • Question 15 - A health-conscious 45-year-old presents with an unexplained acute kidney injury (AKI) and a...

    Incorrect

    • A health-conscious 45-year-old presents with an unexplained acute kidney injury (AKI) and a kidney biopsy reveals the presence of calcium oxalate crystals in the renal tubules. The patient's calcium levels are normal, oxalate levels are elevated, and vitamin D levels are within normal range. Which vitamin overdose could potentially account for this condition?

      Your Answer: Vitamin E

      Correct Answer: Vitamin C

      Explanation:

      The deposition of calcium oxalate in the renal tubules indicates that the patient is experiencing oxalate nephropathy, which is commonly caused by an overdose of vitamin C. Therefore, the correct answer is vitamin C overdose. It should be noted that elevated calcium levels are associated with vitamin D overdose, which is not applicable in this case.

      Understanding Oxalate Nephropathy

      Oxalate nephropathy is a type of sudden kidney damage that occurs when calcium oxalate crystals accumulate in the renal tubules. This condition can be caused by various factors, including the ingestion of ethylene glycol or an overdose of vitamin C. When these crystals build up in the renal tubules, they can cause damage to the tubular epithelium, leading to kidney dysfunction.

      To better understand oxalate nephropathy, it is important to note that the renal tubules are responsible for filtering waste products from the blood and excreting them in the urine. When calcium oxalate crystals accumulate in these tubules, they can disrupt this process and cause damage to the tubular epithelium. This can lead to a range of symptoms, including decreased urine output, swelling in the legs and feet, and fatigue.

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      • Renal System
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  • Question 16 - A 65-year-old patient is admitted to the hospital with a chief complaint of...

    Incorrect

    • A 65-year-old patient is admitted to the hospital with a chief complaint of lethargy and a vague medical history. As part of the assessment, a venous blood gas (VBG) is performed and the results are as follows:

      Na+ 137 mmol/L (135 - 145)
      K+ 3.0 mmol/L (3.5 - 5.0)
      Cl- 105 mEq/L (98 - 106)
      pH 7.29 (7.35-7.45)
      pO2 42mmHg (35 - 45)
      pCO2 46mmHg (42 - 48)
      HCO3- 19 mmol/L (22 - 26)
      BE -3 mmol/L (-2 to +2)

      What is the most likely cause of this patient's presentation?

      Your Answer: Diabetic ketoacidosis

      Correct Answer: Diarrhoea

      Explanation:

      The likely cause of the patient’s normal anion gap metabolic acidosis is diarrhoea. The anion gap calculation shows a normal range of 14 mmol/L, which is within the normal range of 8-14 mmol/L. Diarrhoea causes a loss of bicarbonate from the GI tract, resulting in less alkali to balance out the acid in the blood. Additionally, diarrhoea causes hypokalaemia due to potassium ion loss from the GI tract. COPD, Cushing’s syndrome, and diabetic ketoacidosis are incorrect options as they would result in respiratory acidosis, metabolic alkalosis, and raised anion gap metabolic acidosis, respectively.

      Understanding Metabolic Acidosis

      Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.

      Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.

      Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.

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      • Renal System
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  • Question 17 - A 43-year-old man is admitted to the hospital after the nursing staff reported...

    Correct

    • A 43-year-old man is admitted to the hospital after the nursing staff reported a sudden deterioration in his vital signs. Upon assessment, it is discovered that he is suffering from elevated intracranial pressure due to hydrocephalus. The medical team decides to administer mannitol, an osmotic diuretic, to alleviate the condition.

      What is the primary site of action for mannitol in reducing intracranial pressure?

      Your Answer: Tip of the papilla of the Loop of Henle

      Explanation:

      Where is the osmolarity highest in the nephrons of the kidneys, and why is this relevant to the effectiveness of mannitol as an osmotic diuretic?

      The Loop of Henle and its Role in Renal Physiology

      The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.

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      • Renal System
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  • Question 18 - A 65-year-old man is undergoing assessment for polycythemia and has no history of...

    Correct

    • A 65-year-old man is undergoing assessment for polycythemia and has no history of smoking. What type of solid-organ cancer could be a possible cause?

      Your Answer: Renal cell carcinoma

      Explanation:

      Renal cell carcinoma has the potential to secrete various hormones such as erythropoietin, PTHrP, renin, or ACTH. This can lead to secondary polycythemia, hypercalcemia, or other related conditions. On the other hand, small cell lung cancer can cause ectopic secretion of ACTH or ADH, but not erythropoietin. Pituitary tumors, on the other hand, may secrete prolactin.

      Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.

      Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.

      The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.

      In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.

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      • Renal System
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  • Question 19 - A 49-year-old male presents to the GP for a routine blood check and...

    Correct

    • A 49-year-old male presents to the GP for a routine blood check and follow-up. He has a medical history of angina, hypertension, asthma, and hyperlipidemia. Upon reviewing his medications, it is noted that he is taking fenofibrate, a drug that reduces triglyceride levels and increases the synthesis of high-density lipoprotein (HDL). What is the mechanism of action of this medication?

      Your Answer: Activation of PPAR receptor resulting in increase lipoprotein lipase (LPL) activity

      Explanation:

      Fibrates activate PPAR alpha receptors, which increase LPL activity and reduce triglyceride levels. These drugs are effective in lowering cholesterol.

      Statins work by inhibiting HMG-CoA reductase, which reduces the mevalonate pathway and lowers cholesterol levels.

      Niacin, also known as vitamin B3, inhibits hepatic diacylglycerol acyltransferase-2, which is necessary for triglyceride synthesis.

      Bile acid sequestrants bind to bile salts, reducing the reabsorption of bile acids and lowering cholesterol levels.

      Apolipoprotein E is a protein that plays a role in fat metabolism, specifically in removing chylomicron remnants.

      Understanding Fibrates and Their Role in Managing Hyperlipidaemia

      Fibrates are a class of drugs commonly used to manage hyperlipidaemia, a condition characterized by high levels of lipids in the blood. Specifically, fibrates are effective in reducing elevated triglyceride levels. This is achieved through the activation of PPAR alpha receptors, which in turn increases the activity of LPL, an enzyme responsible for breaking down triglycerides.

      Despite their effectiveness, fibrates are not without side effects. Gastrointestinal side effects are common, and patients may experience symptoms such as nausea, vomiting, and diarrhea. Additionally, there is an increased risk of thromboembolism, a condition where a blood clot forms and blocks a blood vessel.

      In summary, fibrates are a useful tool in managing hyperlipidaemia, particularly in cases where triglyceride levels are elevated. However, patients should be aware of the potential side effects and discuss any concerns with their healthcare provider.

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      • Renal System
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  • Question 20 - A 65-year-old woman with chronic kidney failure has been instructed by her nephrologist...

    Incorrect

    • A 65-year-old woman with chronic kidney failure has been instructed by her nephrologist to adhere to a 'renal diet'. She visits you to gain more knowledge about this.

      What is typically recommended to individuals with chronic kidney disease?

      Your Answer: High protein diet

      Correct Answer: Low potassium diet

      Explanation:

      Dietary Recommendations for Chronic Kidney Disease Patients

      Chronic kidney disease patients are recommended to follow a specific diet that is low in protein, phosphate, sodium, and potassium. This dietary advice is given to reduce the strain on the kidneys, as these substances are typically excreted by the kidneys. By limiting the intake of these nutrients, patients can help slow the progression of their kidney disease and manage their symptoms more effectively. It is important for patients to work closely with their healthcare provider or a registered dietitian to ensure they are meeting their nutritional needs while following these dietary restrictions. With proper guidance and adherence to this diet, patients with chronic kidney disease can improve their overall health and quality of life.

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      • Renal System
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Renal System (7/20) 35%
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