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Question 1
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A 65-year-old male with a history of hypertension, obesity, and chronic kidney disease complains of acute pain and redness in his right ankle, making it difficult for him to bear weight. He denies any recent injury and reports feeling generally well. Laboratory results reveal:
- Hemoglobin: 134 g/L
- Platelets: 312 * 10^9/L
- White blood cells: 9.1 * 10^9/L
- C-reactive protein: 49 mg/L
- Serum urate: 0.3 mmol/L
What is the most probable diagnosis?Your Answer: Gout
Explanation:Once the inflammation has subsided, it is recommended to test the serum urate in suspected cases of gout, as its levels may vary from high to low or normal during an acute attack. Additionally, the patient’s overall good health and moderately elevated CRP levels suggest that septic arthritis is less probable.
Understanding Gout: Symptoms and Diagnosis
Gout is a type of arthritis that causes inflammation and pain in the joints. Patients experience episodes of intense pain that can last for several days, followed by periods of no symptoms. The acute episodes usually reach their peak within 12 hours and can affect various joints, with the first metatarsophalangeal joint being the most commonly affected. Swelling and redness are also common symptoms of gout.
If left untreated, repeated acute episodes of gout can lead to joint damage and chronic joint problems. To diagnose gout, doctors may perform synovial fluid analysis to look for needle-shaped, negatively birefringent monosodium urate crystals under polarised light. Uric acid levels may also be checked once the acute episode has subsided, as they can be high, normal, or low during the attack.
Radiological features of gout include joint effusion, well-defined punched-out erosions with sclerotic margins, and eccentric erosions. Unlike rheumatoid arthritis, gout does not cause periarticular osteopenia. Soft tissue tophi may also be visible.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 2
Correct
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A 42 year old woman comes to your general practice with a complaint of right wrist pain that has been bothering her for a year. The pain worsens with flexion and she rates it as a 7 on the pain scale. She has tried pain medication but with little success. Upon examination, there is no indication of synovitis, but a small effusion is present in the right wrist. Onycholysis is also observed. Purple plaques are present on the extensor surfaces of the elbows bilaterally. What is the clinical diagnosis?
Your Answer: Psoriatic arthritis
Explanation:Psoriatic arthritis is strongly linked to psoriasis, with skin and nail bed changes serving as indicators of this related pathological process. Diagnosis is made through clinical evaluation. For comprehensive information on these conditions, Arthritis Research UK is a valuable resource.
Psoriatic arthropathy is a type of inflammatory arthritis that is associated with psoriasis. It is classified as one of the seronegative spondyloarthropathies and is characterized by joint inflammation that often precedes the development of skin lesions. While it affects both males and females equally, only 10-20% of patients with psoriasis develop this condition. The presentation of psoriatic arthropathy can vary, with the most common types being symmetric polyarthritis and asymmetrical oligoarthritis. Other signs include psoriatic skin lesions, periarticular disease, and nail changes. X-rays may show erosive changes and new bone formation, as well as a pencil-in-cup appearance. Treatment is similar to that of rheumatoid arthritis, but mild cases may only require NSAIDs and newer monoclonal antibodies may be used. Overall, psoriatic arthropathy has a better prognosis than RA.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Correct
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A 65-year-old man presents to the clinic with a complaint of losing 1 stone in weight over the past three months. Apart from this, he has no significant medical history. During the physical examination, his abdomen is soft, and no palpable masses are detected. A normal PR examination is also observed. The patient's blood tests reveal a haemoglobin level of 80 g/L (120-160) and an MCV of 70 fL (80-96). What is the most appropriate initial investigation for this patient?
Your Answer: Upper GI endoscopy and colonoscopy
Explanation:Possible GI Malignancy in a Man with Weight Loss and Microcytic Anaemia
This man is experiencing weight loss and has an unexplained microcytic anaemia. The most probable cause of his blood loss is from the gastrointestinal (GI) tract, as there is no other apparent explanation. This could be due to an occult GI malignancy, which is why the recommended initial investigations are upper and lower GI endoscopy. These tests will help to identify any potential sources of bleeding in the GI tract and determine if there is an underlying malignancy. It is important to diagnose and treat any potential malignancy as early as possible to improve the patient’s prognosis. Therefore, prompt investigation and management are crucial in this case.
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This question is part of the following fields:
- Haematology And Oncology
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Question 4
Incorrect
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As a junior doctor at a general practice, you have an appointment with a 58-year-old man who has been diagnosed with atrial fibrillation. Upon reviewing his notes, you see that he has been prescribed a class three antiarrhythmic medication that blocks potassium channels. Which of the following drugs functions via this mechanism?
Your Answer: Flecainide
Correct Answer: Sotalol
Explanation:Sotalol is classified as a beta-blocker, but it also blocks potassium channels, which slows down the heart rate by delaying ventricular relaxation. This makes it a class three antiarrhythmic agent, along with amiodarone. However, it can also cause a life-threatening type of ventricular tachycardia called torsades de pointes due to its effects on potassium channels.
Digoxin, on the other hand, is a cardiac glycoside that works by reducing conduction through the atrioventricular node, slowing down the ventricular rate in atrial fibrillation and flutter. It also has positive inotropic effects, meaning it can increase the heart’s contractility. It does not fit into the Vaughan Williams classification.
Flecainide is a class one antiarrhythmic agent that blocks fast inward sodium channels and prolongs the refractory period of the heart during diastole.
Propranolol is a beta-blocker and falls under category two of the Vaughan-Williams classification. It is non-selective and used to treat various conditions such as hypertension, thyrotoxicosis, pheochromocytoma, anxiety, angina, essential tremor, and migraine prophylaxis. However, caution should be exercised when using it in patients with asthma as it can cause bronchospasm.
The Vaughan Williams Classification of Antiarrhythmics
The Vaughan Williams classification is a widely used system for categorizing antiarrhythmic drugs based on their mechanism of action. The classification system is divided into four classes, each with a different mechanism of action. Class I drugs block sodium channels, Class II drugs are beta-adrenoceptor antagonists, Class III drugs block potassium channels, and Class IV drugs are calcium channel blockers.
Class Ia drugs, such as quinidine and procainamide, increase the duration of the action potential by blocking sodium channels. However, quinidine toxicity can cause cinchonism, which is characterized by symptoms such as headache, tinnitus, and thrombocytopenia. Procainamide may also cause drug-induced lupus.
Class Ib drugs, such as lidocaine and mexiletine, decrease the duration of the action potential by blocking sodium channels. Class Ic drugs, such as flecainide and propafenone, have no effect on the duration of the action potential but still block sodium channels.
Class II drugs, such as propranolol and metoprolol, are beta-adrenoceptor antagonists that decrease the heart rate and contractility of the heart.
Class III drugs, such as amiodarone and sotalol, block potassium channels, which prolongs the duration of the action potential.
Class IV drugs, such as verapamil and diltiazem, are calcium channel blockers that decrease the influx of calcium ions into the heart, which slows down the heart rate and reduces contractility.
It should be noted that some common antiarrhythmic drugs, such as adenosine, atropine, digoxin, and magnesium, are not included in the Vaughan Williams classification.
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This question is part of the following fields:
- General Principles
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Question 5
Incorrect
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You are on the ward and notice that an elderly patient lying supine in a monitored bed is hypotensive, with a blood pressure of 90/70 mmHg and tachycardic, with a heart rate of 120 beats/minute.
You adjust the bed to raise the patient's legs by 45 degrees and after 1 minute you measure the blood pressure again. The blood pressure increases to 100/75 and you prescribe a 500mL bag of normal saline to be given IV over 15 minutes.
What physiological association explains the increase in the elderly patient's blood pressure?Your Answer: Venous return is proportional to contractility
Correct Answer: Venous return is proportional to stroke volume
Explanation:Fluid responsiveness is typically indicated by changes in cardiac output or stroke volume in response to fluid administration. However, the strength of cardiac muscle contraction is influenced by adrenaline and noradrenaline, which enhance cardiac contractility rather than Starling’s law.
Cardiovascular physiology involves the study of the functions and processes of the heart and blood vessels. One important measure of heart function is the left ventricular ejection fraction, which is calculated by dividing the stroke volume (the amount of blood pumped out of the left ventricle with each heartbeat) by the end diastolic LV volume (the amount of blood in the left ventricle at the end of diastole) and multiplying by 100%. Another key measure is cardiac output, which is the amount of blood pumped by the heart per minute and is calculated by multiplying stroke volume by heart rate.
Pulse pressure is another important measure of cardiovascular function, which is the difference between systolic pressure (the highest pressure in the arteries during a heartbeat) and diastolic pressure (the lowest pressure in the arteries between heartbeats). Factors that can increase pulse pressure include a less compliant aorta (which can occur with age) and increased stroke volume.
Finally, systemic vascular resistance is a measure of the resistance to blood flow in the systemic circulation and is calculated by dividing mean arterial pressure (the average pressure in the arteries during a heartbeat) by cardiac output. Understanding these measures of cardiovascular function is important for diagnosing and treating cardiovascular diseases.
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This question is part of the following fields:
- Cardiovascular System
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Question 6
Correct
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A 55-year-old chronic smoker presents to the cardiology clinic with worsening chest pain during physical activity. After initial investigations, an outpatient coronary angiography is performed which reveals severe stenosis/atheroma in multiple vessels. The patient is informed that this condition is a result of various factors, including the detrimental effects of smoking on the blood vessels.
What is the ultimate stage in the development of this patient's condition?Your Answer: Smooth muscle proliferation and migration from the tunica media into the intima
Explanation:Understanding Atherosclerosis and its Complications
Atherosclerosis is a complex process that occurs over several years. It begins with endothelial dysfunction triggered by factors such as smoking, hypertension, and hyperglycemia. This leads to changes in the endothelium, including inflammation, oxidation, proliferation, and reduced nitric oxide bioavailability. As a result, low-density lipoprotein (LDL) particles infiltrate the subendothelial space, and monocytes migrate from the blood and differentiate into macrophages. These macrophages then phagocytose oxidized LDL, slowly turning into large ‘foam cells’. Smooth muscle proliferation and migration from the tunica media into the intima result in the formation of a fibrous capsule covering the fatty plaque.
Once a plaque has formed, it can cause several complications. For example, it can form a physical blockage in the lumen of the coronary artery, leading to reduced blood flow and oxygen to the myocardium, resulting in angina. Alternatively, the plaque may rupture, potentially causing a complete occlusion of the coronary artery and resulting in a myocardial infarction. It is essential to understand the process of atherosclerosis and its complications to prevent and manage cardiovascular diseases effectively.
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This question is part of the following fields:
- Cardiovascular System
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Question 7
Incorrect
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A 72-year-old man is having a carotid endarterectomy due to recurrent TIAs and the external carotid artery is visible. What is the initial branch of the external carotid artery?
Your Answer: The superficial temporal artery
Correct Answer: The superior thyroid artery
Explanation:The Superior Thyroid Artery and its Branches
The superior thyroid artery is the initial branch of the external carotid artery. It descends downwards along the side of the pharynx before turning anteriorly to provide blood supply to the upper part of the thyroid gland. The external carotid artery has several branches, which are arranged in a descending order from inferior to superior. These branches include the superior thyroid, lingual, facial, occipital, posterior auricular, superficial temporal, and maxillary arteries.
The superior thyroid artery is responsible for supplying blood to the upper pole of the thyroid gland. It is one of the first branches of the external carotid artery and runs downwards along the side of the pharynx before turning anteriorly. The external carotid artery has several branches, which are arranged in a descending order from inferior to superior. These branches include the superior thyroid, lingual, facial, occipital, posterior auricular, superficial temporal, and maxillary arteries.
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This question is part of the following fields:
- Clinical Sciences
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Question 8
Incorrect
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A patient with known multiple myeloma is becoming lethargic and unresponsive, his blood results were all normal, except for his calcium levels (see table below). Alongside rehydration therapy, the doctor decides to administer calcitonin for short term relief of his symptoms.
Na+ 138 mmol/L (135 - 145)
K+ 4.0 mmol/L (3.5 - 5.0)
Urea 5 mmol/L (2.0 - 7.0)
Creatinine 100 µmol/L (55 - 120)
Calcium 3.5 mmol/L (2.1-2.6)
Phosphate 1.0 mmol/L (0.8-1.4)
Magnesium 0.9 mmol/L (0.7-1.0)
What is the mechanism by which this drug will provide a therapeutic effect for a patient in their 60s with known multiple myeloma?Your Answer: Inhibit parathyroid hormone, which will decrease plasma calcium levels
Correct Answer: Inhibit osteoclast activity, which will decrease plasma calcium levels
Explanation:Calcitonin inhibits osteoclasts, leading to a decrease in plasma calcium and phosphate levels. It is produced by the thyroid’s parafollicular or C cells in response to high plasma calcium levels. Administering calcitonin does not affect its own release. It is used as an adjunct to rehydration therapy for hypercalcemia, providing rapid symptom relief. However, bisphosphonates are typically used for long-term correction of calcium levels. Calcitonin does not affect parathyroid hormone activity or the activation of vitamin D, which both contribute to increased plasma calcium levels.
Understanding Calcitonin and Its Role in Regulating Calcium Levels
Calcitonin is a hormone that is produced by the parafollicular cells or C cells of the thyroid gland. It is released in response to high levels of calcium in the blood, which can occur due to various factors such as bone resorption, vitamin D toxicity, or certain cancers. The main function of calcitonin is to decrease the levels of calcium and phosphate in the blood by inhibiting the activity of osteoclasts, which are cells that break down bone tissue and release calcium into the bloodstream.
Calcitonin works by binding to specific receptors on the surface of osteoclasts, which reduces their ability to resorb bone. This leads to a decrease in the release of calcium and phosphate into the bloodstream, which helps to restore normal levels of these minerals. In addition to its effects on bone metabolism, calcitonin also has other physiological functions such as regulating kidney function and modulating the immune system.
Overall, calcitonin plays an important role in maintaining calcium homeostasis in the body and preventing the development of conditions such as hypercalcemia, which can have serious health consequences. By inhibiting osteoclast activity and promoting bone formation, calcitonin helps to maintain the structural integrity of bones and prevent fractures. Understanding the mechanisms of calcitonin action can provide insights into the pathophysiology of bone diseases and inform the development of new treatments for these conditions.
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This question is part of the following fields:
- General Principles
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Question 9
Incorrect
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A 67-year-old man visited his doctor with complaints of weakness in both legs that have been present for the past two months. Initially, he attributed it to his age, but he feels that it is getting worse. The man has difficulty standing up from a seated position, but his arms and shoulders feel fine. He also noticed that the weakness improves slightly when he keeps walking. The patient denies any eye-related symptoms or drooping of the eyelids. According to the patient's wife, he has lost a lot of weight recently despite not dieting or engaging in physical activity. The patient confirms this but says that he feels fine except for a dry cough that has been persistent. The patient has a medical history of diabetes, hypertension, and a smoking history of 40 pack-years. During the examination, the doctor observed slightly decreased air entry on the right side. What is the most likely mechanism underlying this patient's symptoms?
Your Answer: Toxin-mediated inhibition of acetylcholine release at the neuromuscular junction
Correct Answer: Antibodies directed towards presynaptic voltage-gated calcium channels
Explanation:Based on the patient’s symptoms, the two most likely diagnoses are polymyositis and Lambert-Eaton myasthenic syndrome (LEMS), both of which involve weakness in the proximal muscles. However, the patient’s history of smoking, unintentional weight loss, and recent cough suggest a possible diagnosis of lung cancer, particularly small-cell lung cancer which can cause a paraneoplastic syndrome resulting in muscle weakness due to antibodies against presynaptic voltage-gated calcium channels. Unlike myasthenia gravis, muscle weakness in LEMS improves with repetitive use. Dermatomyositis is characterized by CD4 positive T-cells-mediated inflammation of the perimysium and skin symptoms such as a SLE-like malar rash and periorbital rash. Botulism, caused by ingestion of the toxin from Clostridium botulinum, results in dyspnea, dysarthria, dysphagia, and diplopia. Myasthenia gravis, on the other hand, is a neuromuscular junction disorder that causes muscle weakness with repetitive use and is associated with thymoma.
Paraneoplastic Neurological Syndromes and their Associated Antibodies
Paraneoplastic neurological syndromes are a group of disorders that occur in cancer patients and are caused by an immune response to the tumor. One such syndrome is Lambert-Eaton myasthenic syndrome, which is commonly seen in small cell lung cancer patients. This syndrome is characterized by proximal muscle weakness, hyporeflexia, and autonomic features such as dry mouth and impotence. The antibody responsible for this syndrome is directed against voltage-gated calcium channels and has similar features to myasthenia gravis.
Other paraneoplastic neurological syndromes may be associated with detectable antibodies as well. For example, anti-Hu antibodies are associated with small cell lung cancer and can cause painful sensory neuropathy, cerebellar syndromes, and encephalitis. Anti-Yo antibodies are associated with ovarian and breast cancer and can cause a cerebellar syndrome. Anti-Ri antibodies are associated with small cell lung cancer and can cause retinal degeneration.
In summary, paraneoplastic neurological syndromes are a group of disorders that occur in cancer patients and are caused by an immune response to the tumor. These syndromes can be associated with detectable antibodies, which can help with diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 10
Correct
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A 23 years old male presents to his GP with a complaint of inability to flex his left elbow. During examination, the GP observes significant weakness in flexion of his left elbow and supination of his forearm. Which nerve is most likely to be damaged in this case?
Your Answer: Musculocutaneous nerve
Explanation:The musculocutaneous nerve provides innervation to the Bicep, Brachialis, and Coracobrachialis muscles in the upper arm, which are responsible for elbow flexion and forearm supination. If a patient has weak elbow flexion and supination, it may indicate damage to the musculocutaneous nerve. The radial nerve innervates the tricep brachii and extensor muscles in the forearm, while the median nerve is responsible for the anterior compartment of the forearm and does not innervate any arm muscles. The ulnar nerve innervates two forearm muscles and intrinsic hand muscles, excluding the thenar muscles and two lateral lumbricals.
Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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