Master CPS - Renal/Urology
for MSRA

What the MSRA Tests in CPS - Renal/Urology

The CPS - Renal/Urology component of the MSRA tests the ability to manage acute and chronic presentations of renal and urological disease in primary care and emergency settings. Candidates must demonstrate knowledge of diagnostic criteria (e.g., AKI staging by KDIGO, CKD staging by eGFR and ACR), first-line investigations (urine dipstick, renal ultrasound, PSA), and evidence-based management (e.g., NICE guidelines for UTI, renal colic, LUTS, and hypertension in CKD). Emphasis is on recognising red flags (e.g., haematuria with clots, anuria, sepsis from pyelonephritis) and making appropriate referral decisions. Prescribing safety in renal impairment (e.g., metformin, NSAIDs, gentamicin) is frequently tested.

High-Yield Concepts

• AKI Staging (KDIGO): Stage 1: Cr rise ≥26 µmol/L in 48h or 1.5–1.9x baseline. Stage 2: Cr 2.0–2.9x baseline. Stage 3: Cr ≥3.0x baseline or ≥354 µmol/L, or initiation of RRT. Urine output <0.5 mL/kg/h for >6h (stage 1), >12h (stage 2), >24h or anuria >12h (stage 3).
• CKD Classification (NICE 2021): G1: eGFR ≥90, G2: 60–89, G3a: 45–59, G3b: 30–44, G4: 15–29, G5: <15. Add A1 (ACR <3), A2 (ACR 3–30), A3 (ACR >30 mg/mmol). Refer to nephrology if G4/G5, ACR >70, or rapid decline (>5 mL/min/1.73m²/year).
• UTI in Adults (NICE NG109): Lower UTI: treat with nitrofurantoin (if eGFR ≥45) or trimethoprim (if low resistance). Acute pyelonephritis: cefalexin or co-amoxiclav for 7–10 days, send MSU. Recurrent UTI: consider prophylaxis (e.g., nitrofurantoin 50–100 mg nocte) or postcoital dose.
• Acute Scrotum and Testicular Torsion: Sudden severe testicular pain, nausea, absent cremasteric reflex, high-riding testis. Surgical emergency: explore within 6 hours (ideally <4h). Doppler ultrasound if equivocal but must not delay surgery. Salvage rate ~90% if <6h, drops to 50% at 12h.
• Renal Colic (NICE NG118): First-line imaging: non-contrast CT KUB (if typical colic). Alternative: ultrasound if pregnant or young adult. Manage with NSAIDs (e.g., diclofenac 75 mg IM or PR) or paracetamol. Alpha-blockers (tamsulosin 400 mcg) for medical expulsive therapy if distal ureteric stone <10 mm. Refer for urology if stone >10 mm, infection, or failure to pass.
• LUTS in Men (NICE CG97): IPSS questionnaire, digital rectal exam, PSA (if appropriate), flow rate, post-void residual. First-line: alpha-blocker (tamsulosin) or 5-alpha-reductase inhibitor (finasteride) if prostate >30 g. Offer combination if moderate-severe symptoms. Refer if refractory, retention, or suspected cancer.
• Haematuria Assessment (NICE NG12): Visible haematuria: urgent referral (2-week wait) for urology. Non-visible haematuria: if persistent (≥3 dipstick positives) with or without proteinuria, refer if age >60 or risk factors (smoking, occupational). Also check eGFR, ACR, and BP.
• Prescribing in Renal Impairment: Avoid NSAIDs if eGFR <30. Metformin: stop if eGFR <30 (risk of lactic acidosis). Gentamicin: once-daily dosing, check levels. ACEi/ARB: beneficial in CKD with proteinuria (ACR >30), but monitor K+ and Cr. Stop if Cr rises >30% within 3 months.

Common Traps in CPS - Renal/Urology Questions

• Confusing AKI stage 1 with 'pre-renal' — remember that AKI is defined by Cr/urine output, not aetiology.
• Using nitrofurantoin for pyelonephritis — it does not achieve adequate renal tissue levels.
• Ordering CT KUB for all flank pain — misses alternative diagnoses like AAA or pneumonia; use clinical context.
• Assuming all haematuria with infection is benign — always recheck dipstick after treatment, as persistent haematuria needs referral.
• Forgetting to stop metformin in CKD G4 — it accumulates and can cause fatal lactic acidosis.
• Treating asymptomatic bacteriuria in non-pregnant adults — only treat in pregnancy, prior to urological procedures, or in renal transplant.

How to Revise CPS - Renal/Urology for the MSRA

Focus on clinical decision-making at the primary care–secondary care interface: when to refer urgently (e.g., AKI stage 2/3, visible haematuria, testicular torsion), when to manage conservatively (e.g., uncomplicated renal colic, simple UTI), and when to adjust medications for renal function. Questions often present as a short clinical scenario with a single best answer from a list of management steps — practise recognising red flags and applying NICE thresholds (e.g., eGFR, ACR, stone size). Also, be comfortable with interpreting basic renal biochemistry and urine dipstick results. High-yield: AKI/CKD staging, UTI treatment choice, and acute scrotum triage.

Practise it: MedLumen has 50 CPS - Renal/Urology questions for the MSRA, each with a full explanation and references.