MRCP Flashcards
Inhibition of which enzyme is responsible for the pseudohyperaldosteronism associated with liquorice?
11 beta hydroxysteroid dehydrogenase (11 bHSD)
11bHSD is responsible for the conversion of cortisol to the inactive cortisone, preventing activation of the mineralocorticoid receptor by cortisol but permitting activation by aldosterone.
Shunted pathway i guess
A 23-year-old obese female with known tuberculosis presents with ulcerating nodules on the back of her legs.
Which of the following is the most likely diagnosis?
A. Erythema nodosum
B. Erythema marginatum
C. Erythema induratum
D. Lupus vulgaris
E. Lupus pernio
C. Erythema induration
EI is a form of panniculitis characterised by chronic, recurrent, tender, subcutaneous, and sometimes ulcerated nodules on the lower legs that may also appear elsewhere
Lupus vulgaris
lupus vulgaris is a chronic, progressive, and destructive form of cutaneous tuberculosis in patients with a moderate or high degree of immunity. It occurs more commonly in females than in males.
The classical lesions consist of reddish-brown plaques not nodules. The lesions progress by peripheral extension and central healing, atrophy, and scarring. The areas of predilection are head and neck (80%), followed by arms, legs, then trunk.
Lupus pernio
Raised lesions associated with sarcoid. Poor prognostic marker
Male patient with HbA1c reasonable, but he complains of hypoglycaemic events particularly during exercise. He has been commenced on the insulin analogue, aspart insulin.
What is the rationale for changing him to insulin analogue?
More rapid onset of action, and shorter duration of action than conventional short acting insulin.
Consequently studies reveal reduced post-prandial glucose excursions versus soluble insulin and potentially a reduced incidence of hypoglycaemia although the evidence for this is debated.
Differentiating features between pre-renal and intrinsic renal failure?
Pre-renal: no red cell or protein casts Urine Na <20 Osmol >500 urine/plasma urea ratio >8 urine/plasma creatinine >40
ATN suggested if:
Urine Na >40, Osmol <350, Urine/plasma urea ratio <3 (not filtering properly)
Urine/plasma creatinine < 20
Leflunamide
If aspartate aminotransferase (AST) or alanine aminotransferase (ALT) is between two and three times the upper limit of normal, and the leflunomide dose is more than 10 mg daily, the dose should be reduced to 10 mg and LFTs rechecked weekly until normalised. If the ALT and AST are returning to normal, the patient should be left on 10 mg per day. It the LFTs remain elevated, leflunomide should be stopped and discussed with the specialist team.
If the AST or ALT is more than three times the upper limit of normal, the LFTs should be rechecked within 72 hours. If they remain more than three times the reference range, leflunomide should be stopped and washout considered (cholestyramine and activated charcoal). It is important to note that the half life of leflunomide is usually two weeks (mean 1-4) therefore if a rapid response is required, washout should be considered.
AIP
Presents with abdominal pain, neuropsychiatric symptoms, autonomic instability, dark urine. It is an acute neurovisceral porphyria resulting from a partial deficiency of the heme biosynthetic enzyme porphobilinogen deaminase (PBGD). It is an autosomal dominant disorder with low penetrance. This leads to increased urinary porphobilinogen and aminolaevulinic acid, especially during attacks. The urine classically turns deep red on standing. Hyponatraemia is often present during acute attacks and may, in part, be due to inappropriate secretion of antidiuretic hormone.
Diagnosis with urine spot PBG, urine ALA. total porphyrin level, stool and plasma.
Rx: hemin (severe), glucose loading (mild). Opioid analgesics, benzos, beta blockers, anti-emetics.
Triggers: starvation, medications (phenytoin, barbiturates, rifampicin), progesterone,
