Master Renal & Urology
for PLAB 1

What the PLAB 1 Tests in Renal & Urology

PLAB 1 Renal & Urology tests your ability to manage common presentations: acute kidney injury (AKI), chronic kidney disease (CKD), urinary tract infections (UTI), stone disease, haematuria, prostatism, and scrotal emergencies. You must know diagnostic criteria (e.g., KDIGO AKI staging), first-line investigations (urine dipstick, renal ultrasound, eGFR), and management guidelines (NICE for CKD, EAU for urolithiasis). Emphasis is on recognising when to refer (e.g., suspected malignancy in haematuria, acute urinary retention with post-void residual >200 mL) and selecting appropriate antibiotics (nitrofurantoin or trimethoprim for uncomplicated UTI, co-amoxiclav for pyelonephritis in pregnancy). Drug dosing in renal impairment (e.g., metformin, gentamicin) and fluid balance in AKI are frequently tested.

High-Yield Concepts

• AKI KDIGO Staging & Management: Stage 1: creatinine rise ≥26 µmol/L in 48h or 1.5–1.9x baseline; urine output <0.5 mL/kg/h for 6–12h. Stage 2: creatinine 2.0–2.9x baseline; urine output <0.5 mL/kg/h for ≥12h. Stage 3: creatinine ≥3.0x baseline or ≥354 µmol/L or initiation of RRT; urine output <0.3 mL/kg/h for ≥24h or anuria for ≥12h. First-line: stop nephrotoxins (ACEi, ARB, NSAIDs, metformin), fluid challenge if hypovolaemic, then furosemide if oliguric.
• CKD Staging & Referral Criteria (NICE): eGFR (mL/min/1.73m²): G1 ≥90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 <15. Albuminuria categories: A1 <3 mg/mmol, A2 3–30, A3 >30. Refer to nephrology if eGFR <30 (G4/G5), or ACR >70 mg/mmol, or rapid decline (>5 mL/min/year), or suspected glomerulonephritis (e.g., haematuria with proteinuria).
• Urinary Tract Infection in Adults: Uncomplicated lower UTI in non-pregnant women: first-line nitrofurantoin 100 mg MR BD for 3 days (if eGFR ≥45) or trimethoprim 200 mg BD for 3 days (if local resistance <20%). Complicated UTI/pyelonephritis: send MSU, start co-amoxiclav 500/125 mg TDS or ciprofloxacin 500 mg BD (if no contraindication) for 7–14 days. In pregnancy: treat all asymptomatic bacteriuria with nitrofurantoin (avoid at term) or cephalexin.
• Renal Stone Management (EAU Guidelines): Stones <5 mm: 80% pass spontaneously; offer tamsulosin 0.4 mg OD for medical expulsive therapy (MET). Stones 5–10 mm: MET plus reassess in 4–6 weeks. Proximal ureteric stones >10 mm: ESWL or ureteroscopy. Distal ureteric stones >10 mm: ureteroscopy with laser lithotripsy. Uric acid stones: alkalinise urine with potassium citrate to pH 6.5–7.0.
• Haematuria Assessment (NICE): Visible haematuria (any age) or non-visible haematuria in patients ≥60 with unexplained ACR >30 mg/mmol: refer on 2WW for suspected urological cancer. Non-visible haematuria with ACR <30 in patients <60: repeat dipstick; if persistent, check eGFR, ACR, and renal US; refer to urology if proteinuria >50 mg/mmol or eGFR <30.
• Benign Prostatic Hyperplasia (BPH) & Acute Urinary Retention: First-line medical therapy: alpha-blocker (tamsulosin 0.4 mg OD) ± 5-alpha-reductase inhibitor (finasteride 5 mg OD) if prostate >40 g. Acute retention: catheterise (16–18 Fr Foley), measure post-void residual (PVR); if PVR >200 mL, start alpha-blocker and trial without catheter (TWOC) after 48h. Refer for TURP if failed TWOC or recurrent retention.
• Testicular Torsion: Surgical emergency: sudden onset severe scrotal pain with nausea/vomiting, absent cremasteric reflex, high-riding testis. Do not wait for Doppler US if history is suggestive; proceed to scrotal exploration within 6 hours of onset. If torsion confirmed, perform orchidopexy of both testes.
• Drug Dosing in Renal Impairment: Metformin: stop if eGFR <30 (risk of lactic acidosis). Gentamicin: once-daily dosing (5–7 mg/kg), monitor trough levels (<1 mg/L pre-dose); avoid if eGFR <20. ACEi/ARB: continue until eGFR <30, then reduce dose or stop if hyperkalaemia >6.0 mmol/L. NSAIDs: avoid if eGFR <30.

Common Traps in Renal & Urology Questions

• Confusing AKI with CKD: AKI has acute creatinine rise over days, CKD has low eGFR for >3 months; always check baseline creatinine.
• In uncomplicated UTI, sending MSU is not required before starting empirical antibiotics; only send if complicated, recurrent, or pregnancy.
• For haematuria, remember that non-visible haematuria with proteinuria >50 mg/mmol requires nephrology referral, not urology.
• In acute scrotal pain, do not rely on Doppler US to rule out torsion if history is classic; time-critical exploration is mandatory.
• In BPH, starting finasteride alone without alpha-blocker can worsen retention initially due to delayed onset of effect (6 months).
• For renal stones, tamsulosin is only effective for distal ureteric stones >5 mm; it does not help proximal stones or renal calculi.

How to Revise Renal & Urology for the PLAB 1

Prioritise AKI staging and management (fluid challenge vs. furosemide), CKD referral criteria (eGFR <30 or ACR >70), and UTI antibiotic choices (nitrofurantoin vs. trimethoprim vs. co-amoxiclav). Questions often present as clinical vignettes with lab results and ask for next step (e.g., 'which drug to stop?' or 'when to refer?'). Practise interpreting eGFR, creatinine trends, and urine dipstick results. Stone management and scrotal emergencies are high-yield for surgical decision-making. Memorise key cut-offs: eGFR <30 stop metformin, PVR >200 mL for retention, and 6-hour window for torsion. Use NICE and EAU guidelines as your framework.

Practise it: MedLumen has 50 Renal & Urology questions for the PLAB 1, each with a full explanation and references.