Free UKMLA renal and urology questions with explanations

E. Sine-wave QRS-T fusion

Hyperkalaemic ECG changes progress from peaked T waves through PR prolongation and loss of P waves to QRS widening, and finally to a sine-wave pattern where the widened QRS merges with the T wave, the pre-terminal change immediately preceding ventricular fibrillation or asystole. Sine-wave morphology is a peri-arrest emergency mandating immediate IV calcium gluconate for myocardial stabilisation alongside insulin-dextrose to shift potassium.

B. Myoglobinuria from rhabdomyolysis

Crush injury with tense, swollen muscle compartments and pigment-positive but cell-negative urine points to rhabdomyolysis; circulating myoglobin is filtered, precipitates with Tamm-Horsfall protein in acidic tubules, and causes direct tubular toxicity plus renal vasoconstriction. Rhabdomyolysis is a discrete major AKI risk factor, distinct from hypovolaemia or electrolyte derangements which act as cofactors rather than the primary insult.

D. Ramipril

In polycystic kidney disease expanding cysts compress the intrarenal vessels, activating the renin-angiotensin system, so hypertension appears early (often in the twenties or thirties) and accelerates the loss of kidney function. An ACE inhibitor (or an angiotensin receptor blocker) is the first-line antihypertensive because it lowers systemic and intraglomerular pressure and reduces albuminuria, addressing the mechanism rather than just the number. Amlodipine would lower the blood pressure equally but does nothing for renin-driven glomerular hypertension or albuminuria. Potassium and creatinine should be checked one to two weeks after starting.

B. Autosomal dominant polycystic kidney disease

This patient has autosomal dominant polycystic kidney disease (ADPKD), evidenced by bilateral enlarged kidneys with multiple cysts, hepatic cysts, reduced eGFR and a paternal history of dialysis, fulfilling the Ravine/Pei-Ravine ultrasound criteria in the context of a positive family history. ADPKD is caused by mutations in PKD1 (around 85%) or PKD2, and progresses to end-stage renal disease in many patients by later middle age.

B. Acute pyelonephritis

The triad of high fever with rigors, unilateral loin pain with costovertebral angle tenderness, and lower urinary tract symptoms with a positive urinalysis (nitrites, leucocytes) indicates acute pyelonephritis, an upper urinary tract infection. Prompt empirical antibiotics are recommended (e.g. oral cefalexin, or ciprofloxacin only if other first-choice antibiotics are unsuitable, or IV therapy if unable to tolerate oral or systemically unwell), with imaging to exclude obstruction in diabetic or deteriorating patients.

E. Urea, creatinine, and potassium

ACE inhibitors can precipitate acute kidney injury and hyperkalaemia, especially in older patients or those with renal impairment. Check urea, creatinine and potassium before starting and 1 to 2 weeks after initiation or dose titration; a creatinine rise of less than 30% (or eGFR fall of less than 25%) is acceptable, a potassium of 6.0 mmol/L or more means stopping the drug (once other hyperkalaemia-promoting medicines have been discontinued), and a creatinine rise of 30% or more (or eGFR fall of 25% or more) should prompt investigation of other causes such as volume depletion or NSAIDs and, if none is found, stopping the drug or reducing to a previously tolerated dose.

D. Metolazone

Metolazone is a thiazide-like diuretic blocking the sodium-chloride cotransporter (NCC) in the distal convoluted tubule; combined with a loop diuretic it produces sequential nephron blockade, overcoming the compensatory distal sodium reabsorption that limits loop monotherapy. Unlike true thiazides, metolazone retains efficacy at low eGFR, making it the preferred UK adjunct at 2.5–5 mg given 30 minutes before furosemide with close electrolyte monitoring.

C. Paraphimosis

Paraphimosis occurs when a retracted foreskin is left behind the glans, most often after catheterisation or cleaning in an older man; the tight preputial ring obstructs venous and lymphatic return, the glans and distal prepuce swell, and the ring becomes progressively harder to reduce. It is a urological emergency because prolonged constriction leads to arterial compromise and glans necrosis. Balanoposthitis inflames the glans and foreskin together without a constricting ring, priapism is a persistent painful erection of the shaft rather than glans swelling, phimosis is a foreskin that cannot be retracted (the opposite problem), and cellulitis spreads diffusely rather than forming a discrete band behind the glans.

A. Circumcision

A pale, sclerotic, non-distensible preputial ring with white atrophic patches on the glans is lichen sclerosus of the foreskin (balanitis xerotica obliterans), the commonest cause of pathological phimosis in boys. Unlike physiological phimosis it does not resolve, it obstructs the stream and predisposes to recurrent balanitis, and it is the main absolute indication for circumcision, which removes the diseased tissue and provides histological confirmation. Topical steroids can help a non-scarred tight foreskin but rarely reverse established scarring with obstructive symptoms. Preputioplasty is avoided in lichen sclerosus because the disease recurs in the retained foreskin. The urethral meatus can also be involved, so the boy needs follow-up for meatal stenosis after surgery.

E. Reassure; no follow-up imaging required

A lesion that is anechoic, has a thin smooth wall, shows posterior acoustic enhancement and contains no septations, calcification or solid tissue is a simple renal cyst (Bosniak category I). These are benign, extremely common with age, and need no follow-up or referral. Further cross-sectional imaging with contrast is reserved for cysts with complex features, such as thick or irregular walls, multiple or thick septa, calcification or an enhancing solid component, because those features raise the possibility of cystic renal cell carcinoma. Aspiration or deroofing is considered only for large cysts causing pain, obstruction or hypertension.