Relative Risk = (Probability of event in exposed group) / (Probability of event in not exposed group). The relative risk is mistaken by some, with the odds ratio and absolute risk. Relative risk is the ratio of the probability of an event occurring with an exposure versus the probability of the event occurring without the exposure. Thus to calculate the relative risk, we must know the exposure status of all individuals (either exposed or not exposed). This implies that relative risk is only appropriate for cases where the exposure status and incidence of disease can be accurately determined such as prospective cohort studies.

Giardiasis also known as travellers diarrhoea is caused by Giardia lamblia, which is an anaerobic parasite affecting the small intestine. It can lead to diarrhoea, flatulence, abdominal cramps, malodourous greasy stools and intestinal malabsorption. It can also cause bloody diarrhoea. The investigation of choice is stool examination for trophozoites and cysts. It is treated by metronidazole and tinidazole as first line therapies.

The question describes a patient who has had an ileal resection. Bile acids are reabsorbed in the distal ileum. Since this has been resected in this patient, one would expect her to have malabsorption of bile acids, causing her diarrhoea. This is a more likely correct answer than a Crohn’s flare, bacterial overgrowth, gastroenteritis, or tropical sprue, given the details included in the question prompt.

The major endocrine functions of adrenal gland are to produce catecholamines and steroids. Catecholamine, synthesized by the adrenal medulla, is responsible for blood pressure and blood flow regulation whereas steroids produced by the cortex control energy and water homeostasis and immune responses. Glucocorticoids, a major group of adrenal steroids, have a stimulatory effect on catecholamine synthesis in the medulla.

This patient present with the classical symptoms of Amyotrophic neuralgia, characterised by sudden onset of pain in the shoulders that radiate down to the forearms and later resolve spontaneously but is followed by muscle wasting.

Intensive physical training and participation in competitive sports during childhood and early adolescence may affect athletes’ pubertal development.
Female athletes who do not begin secondary sexual development by the age of 14 or menstruation by the age of 16 warrant a comprehensive evaluation and treatment.
Since she is still 14, adequate diet and observation are enough.

A translocation between chromosome 15 and 17 is seen in acute promyelocytic leukaemia (APL), which is known to carry a good prognosis.

Acute myeloid leukaemia (AML) is the acute expansion of the myeloid stem line, which may occur as a primary disease or follow the secondary transformation of a myeloproliferative disorder. It is more common over the age of 45 and is characterized by signs and symptoms largely related to bone marrow failure such as anaemia (pallor, lethargy), frequent infections due to neutropenia (although the total leucocyte count may be very high), thrombocytopaenia (bleeding), ostealgia, and splenomegaly. The disease has poor prognosis if:

The disease has poor prognosis if:
1. Age of the patient >60 years
2. >20% blasts seen after the first course of chemotherapy
3. Chromosomal aberration with deletion of part of chromosome 5 or 7.

APL is an aggressive form of AML. It is associated with t(15;17) and has a good prognosis. The general age of presentation is less than that in other types of AML (average age is 25 years old). On blood film, abundant Auer rods are seen with myeloperoxidase staining. Thrombocytopaenia or DIC is seen in patients presenting with this disease.

Whilst asthma and COPD are different diseases they cause similar symptoms, which can present a challenge in identifying which of the two diseases a patient is suffering from. COPD causes chronic symptoms and narrowed airways which do not respond to treatment to open them up. In the case of asthma the constriction of the airways through inflammation tends to come and go and treatment to reduce inflammation and to open up the airways usually works well.

COPD is more likely than asthma to cause a chronic cough with phlegm and is rare before the age of 35 whilst asthma is common in under-35s. Disturbed sleep caused by breathlessness and wheeze is more likely in cases of asthma, as is a history of allergies, eczema and hay fever. Differentiating between COPD and asthma requires a history of both symptoms and spirometry. The spirometry history should include post bronchodilator measurements, the degree of reversibility and, ideally, home monitoring which gives a history of diurnal variation.

Airflow Obstruction: Both asthma and COPD are characterised by airflow obstruction. Airflow obstruction is defined as a reduced FEV1 and a reduced FEV1/FVC ratio, such that FEV1 is less than 80% of that predicted, and FEV1/FVC is less than 0.7.

These episodes are usually associated with widespread, but variable, airflow obstruction within the lung that is often reversible either spontaneously or with treatment.

COPD: COPD is a chronic, slowly progressive disorder characterised by airflow obstruction (reduced FEV1 and FEV1/VC ratio) that does not change markedly over several months. The airflow obstruction is not fully reversible.

Spirometry COPD Asthma
VC Reduced Nearly normal
FEV1 Reduced Reduced in attack
FVC (or FEV6) Reduced Nearly normal
FEV1 Ratio
(of VC/FVC/FEV6) Reduced in attack

This man has a low FEV1 and FVC. His diffusions capacity is also low despite having a normal total lung capacity. These values confirm a diagnosis of COPD.

Bronchiectasis is a long-term condition where the airways of the lungs become abnormally widened, leading to a build-up of excess mucus that can make the lungs more vulnerable to infection. The most common symptoms of bronchiectasis include:
– a persistent productive cough
– breathlessness.

The 3 most common causes in the UK are:
– a lung infection in the past, such as pneumonia or whooping cough, that damages the bronchi
– underlying problems with the immune system (the body’s defence against infection) that make the bronchi more vulnerable to damage from an infection
– allergic bronchopulmonary aspergillosis (ABPA) – an allergy to a certain type of fungi that can cause the bronchi to become inflamed if spores from the fungi are inhaled

The two statements that fit the characteristics of doxapram are, epilepsy is a contraindication for doxapram use and concurrent use with theophylline may increase agitation.

Doxapram is a central respiratory stimulant. In clinical practice, doxapram is usually used for patients who have an acute exacerbation of chronic obstructive pulmonary disease (COPD) who are unsuitable for admission to the intensive therapy unit for ventilatory support. Doxapram infusion may buy an extra 24 h to allow for recovery.

Contraindications include: ischaemic heart disease, epilepsy, cerebral oedema, acute stroke, asthma, hypertension, hyperthyroidism, and pheochromocytoma.
The infusion may worsen agitation and dyspnoea and lead to hypertension, nausea, vomiting and urinary retention.

Drug interactions:
Concomitant administration of doxapram and aminophylline (theophylline) can cause increased skeletal muscle activity, agitation, and hyperactivity.

The normal partial pressure reference values are:
– PaO2 more than 80 mmHg (11 kPa)
– PaCO2 less than 45 mmHg (6.0 kPa).
This patient has an elevated PaCO2 (7.4kPa)
Hypoxemia (PaO2 <8kPa) with hypercapnia (PaCO2 >6.0kPa).
The pH is also lower than 7.35 at 7.3

Type 2 respiratory failure is caused by inadequate alveolar ventilation; both oxygen and carbon dioxide are affected. Defined as the build-up of carbon dioxide levels (PaCO2) that has been generated by the body but cannot be eliminated. The underlying causes include:
– Increased airways resistance (chronic obstructive pulmonary disease, asthma, suffocation)
– Reduced breathing effort (drug effects, brain stem lesion, extreme obesity)
– A decrease in the area of the lung available for gas exchange (such as in chronic bronchitis)
– Neuromuscular problems (Guillain–Barré syndrome, motor neuron disease)
– Deformed (kyphoscoliosis), rigid (ankylosing spondylitis), or flail chest.

Chloride channels are involved in a diverse set of functions in normal physiology and acquired diseases. Additionally, there are genetic diseases caused by mutations in chloride channels (channelopathies) — the most common being cystic fibrosis, which has a prevalence of 1 in 2,000 Caucasians.

Neutrophilia is also commonly associated with polycythaemia vera.

Polycythaemia vera (PV), also known as polycythaemia rubra vera, is a myeloproliferative disorder caused by clonal proliferation of marrow stem cells leading to an increase in red cell volume, often accompanied by overproduction of neutrophils and platelets. It has peak incidence in the sixth decade of life, with typical features including hyperviscosity, pruritus, splenomegaly, haemorrhage (secondary to abnormal platelet function), and plethoric appearance.

Some management options of PV include lose-dose aspirin, venesection (first-line treatment), hydroxyurea (slightly increased risk of secondary leukaemia), and radioactive phosphorus (P-32) therapy.

In PV, thrombotic events are a significant cause of morbidity and mortality. 5–15% of the cases progress to myelofibrosis or AML. The risk of having AML is increased with chemotherapy treatment.

Fc Receptors include the IgG receptors (FcγR), high-affinity IgE receptor (FcεRI), IgA and IgA/IgM receptors, and neonatal Fc receptor for IgG (FcRn). In particular, the FcγRs have been well known to play an important role in many biologic processes including those associated with the response to infection and cancer as well as in the pathogenesis of immune-mediated diseases. Fc receptors, the receptors for the Fc region of immunoglobulins, play an essential role in antibody-dependent immune responses. Fc receptors are detected on many types of hematopoietic cells including macrophages, neutrophils, dendritic cells, eosinophils, basophils, mast cells, and NK cells. Plasma cells produce five classes of antibodies, IgA, IgD, IgE, IgG and IgM. Fc receptors with an Ig superfamily related structure exist that correspond to each of these classes of immunoglobulins.

The patient is most likely to have Bulimia nervosa. A young girl with a low body mass contributes to the low urea. Hypokalaemia and hyponatraemia are due to vomiting. Her urine sodium is also low.
– In Addison’s diseases, there are low levels of sodium and high levels of potassium in the blood. In acute adrenal crisis: The most consistent finding is elevated blood urea nitrogen (BUN) and creatinine. Urinary and sweat sodium also may be elevated.
– In Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) there is hyponatremia with corresponding hypo-osmolality, continued renal excretion of sodium, urine less than maximally dilute and absence of clinical evidence of volume depletion.

The pattern of muscle involvement seen with quadriceps and long-finger flexors is characteristic of inclusion body myositis, an inflammatory myopathy. Polymyositis is likely to cause a predominantly proximal weakness, associated with muscle pain. The signs and symptoms are not consistent with upper cord compression, as there would likely be sensory signs, reflex changes, and possible urinary symptoms. Motor neuron disease cannot be ruled out, but there are no findings of upper motor neuron or bulbar features.

Hormone replacement therapy (HRT) involves the use of a small dose of oestrogen, combined with a progestogen (in women with a uterus), to help alleviate menopausal symptoms. The main indication is the control of vasomotor symptoms. The other indications, such as reversal of vaginal atrophy and prevention of osteoporosis, should be treated with other agents as first-line therapies.

Deletion of part of chromosome 5 or 7 is a poor prognostic feature for acute myeloid leukaemia (AML).

AML is the acute expansion of the myeloid stem line, which may occur as a primary disease or follow the secondary transformation of a myeloproliferative disorder. It is more common over the age of 45 and is characterized by signs and symptoms largely related to bone marrow failure such as anaemia (pallor, lethargy), frequent infections due to neutropenia (although the total leucocyte count may be very high), thrombocytopaenia (bleeding), ostealgia, and splenomegaly.

The disease has poor prognosis if:
1. Age of the patient >60 years
2. >20% blasts seen after the first course of chemotherapy
3. Chromosomal aberration with deletion of part of chromosome 5 or 7.

Acute promyelocytic leukaemia (APL) is an aggressive form of AML.

Because of the patient’s presentation with flank pain that radiates to the groin, we are suspecting renal colic. We should follow guidelines for acute renal management and prescribe IM diclofenac for immediate relief of pain.

The most probable diagnosis of this patient is Cotard syndrome.

Cotard syndrome is a rare mental disorder where the affected patient believes that they (or in some cases just a part of their body) is either dead or non-existent. This delusion is often difficult to treat and can result in significant problems due to patients stopping eating or drinking as they deem it not necessary. Cotard syndrome is often associated with severe depression and psychotic disorders.

Other delusional syndromes:
– Othello syndrome is a delusional belief that a patients partner is committing infidelity despite no evidence of this. It can often result in violence and controlling behaviour.
– De Clerambault syndrome (otherwise known as erotomania), is where a patient believes that a person of higher social or professional standing is in love with them. Often this presents with people who believe celebrities are in love with them.
– Capgras syndrome is characterised by a person believing their friend or relative had been replaced by an exact double.
– Couvade syndrome is also known as ‘sympathetic pregnancy’. It affects fathers, particularly during the first and third trimesters of pregnancy, who suffer the somatic features of pregnancy.
– Ekbom syndrome is also known as delusional parasitosis and is the belief that they are infected with parasites or have ‘bugs’ under their skin. This can vary from the classic psychosis symptoms in narcotic use where the user can ‘see’ bugs crawling under their skin or can be a patient who believes that they are infested with snakes.

The main mechanism of fibrate drugs is activation of gene transcription factors known as PPARs, particularly PPAR-α, which regulate the expression of genes that control lipoprotein metabolism. There are several consequences of PPAR-α activation, which reduce circulating LDL cholesterol and triglycerides and increase HDL cholesterol.

The vas deferens is a long tube that connects the epididymis to the ejaculatory ducts. It acts as a canal through which mature sperm may pass through the penis during ejaculation.

Most men with CF (97-98 percent) are infertile because of a blockage or absence of the vas deferens, known as congenital bilateral absence of the vas deferens (CBAVD). The sperm never makes it into the semen, making it impossible for them to reach and fertilize an egg through intercourse. The absence of sperm in the semen can also contribute to men with CF having thinner ejaculate and lower semen volume.

This woman is receiving methotrexate, an immunosuppressant, to control her rheumatoid arthritis. In such immunocompromised patients, BNF suggests clarithromycin as first-line management.

Giant Cell Arteritis (Temporal Arteritis) is the most probable diagnosis. GCA should always be considered in the differential diagnosis of a new-onset headache in patients 50 years of age or older with an elevated erythrocyte sedimentation rate. Temporal artery biopsy remains the criterion standard for diagnosis of this granulomatous vasculitis. High-dose corticosteroid therapy is the universally accepted treatment.

The given history is more compatible with spontaneous pneumothorax. Left-sided pneumothoraxes may be associated with a clicking noise, which is heard with each heart-beat and can sometimes be heard by the patient.

The most common cause of cervical radiculopathy is degenerative disease in the cervical spine. In 80–90% of patients with cervical radiculopathy, the C5/C6 or C6/C7 motion segments are affected by degenerative disease and the nearby C6 and/or C7 nerve roots are producing the symptoms. Patients with cervical radiculopathy complain of neck pain and radiating pain in the arm sometimes combined with sensory and motor disturbances in the arm and/or hand. These symptoms are accepted as being caused by the nerve root compression. Middle finger and palm of the hand are mostly rising the suspicion for C7 nerve root and median nerve involvement.

Biguanides (Metformin):
People who take metformin alone should be able to fast safely given that the possibility of hypoglycaemia is minimal. However, patients should modify its dose and administration timing to provide two-thirds of the total daily dose, which should be taken immediately with the sunset meal, while the other third is taken before the predawn meal.

Thiazolidinediones: No change needed.

Sulfonylurea:
Once-daily sulfonylurea (such as glimepiride or gliclazide MR): the total daily dose should be taken with the sunset meal.
Shorter-acting sulfonylurea (such as gliclazide twice daily): the same daily dose remains unchanged, and one dose should be taken at the sunset meal and the other at the predawn meal.
Long-acting sulfonylurea (such as glibenclamide): these agents should be avoided.

It is important that diabetic patients to eat a healthy balanced diet and choose foods with a low glycaemic index (such as complex carbohydrates), which can help to maintain blood glucose levels during fasting. Moreover, it is crucial to consume adequate fluids to prevent dehydration. Physical activity is encouraged, especially during non-fasting periods.

Constitutional symptoms such as weight loss, evening pyrexia and night sweats are associated with Mycobacterium Tuberculosis (TB). TB can affect any system of the body and should be top in the list of differentials particularly if the patient has a history of contact with a known TB patient.

Normal distribution, also known as the Gaussian distribution, is a probability distribution that is symmetric about the mean. The normal distribution has the following properties:
– It is symmetric around the mode, the median and the mean of the distribution.
– It is unimodal
– The area under the curve and over the x-axis is unity (i.e. equal to one).
– Its density has two inflection points.
– Its density is log-concave.
The standard deviation (SD) is a measure of how much dispersion exists from the mean. SD = square root (variance)

Many drugs are responsible for causing drug induced lupus. However, it is most commonly associated with hydralazine, procainamide and quinidine.