Renal & urology

An abrupt (hours–days) decline in kidney function defined by KDIGO criteria: a rise in creatinine ≥26 µmol/L in 48 h, a ≥1.5× rise from baseline within 7 days, or urine output 6 h. The pivotal first move is the pre-renal / intrinsic / post-renal triage, because it sets the management — fluids, stop nephrotoxins, or relieve obstruction.

Breakdown of skeletal muscle releasing myoglobin (nephrotoxic), potassium, phosphate and creatine kinase. Causes include a long lie after a fall/collapse, crush injury, prolonged seizures, extreme exertion, statins, and drugs/toxins. The danger is AKI (myoglobin casts) plus life-threatening hyperkalaemia; treatment is aggressive IV fluids and treating the hyperkalaemia.

Abnormal kidney function or structure present for more than 3 months, classified by the GFR category (G1–G5) and the albuminuria category (A1–A3) — the 'CKD heat map'. The commonest causes are diabetes and hypertension. Management slows progression (BP control, ACE inhibitor/ARB, SGLT2 inhibitor), treats the complications (anaemia, bone disease, acidosis), and reduces cardiovascular risk — the leading cause of death in CKD.

Established kidney failure (CKD stage G5, eGFR <15) where renal function is insufficient to sustain life without renal replacement therapy. The three RRT options are haemodialysis, peritoneal dialysis and transplantation (the best outcomes, when suitable); conservative (supportive) care is appropriate for some. The high-yield exam points are dialysis indications, access, and transplant immunosuppression/complications.

An inherited cystic kidney disease — most commonly autosomal dominant (ADPKD, PKD1/PKD2 mutations) — in which progressive cyst formation enlarges the kidneys and causes hypertension, haematuria, pain and progression to renal failure by middle age. The crucial extra-renal association is intracranial (berry) aneurysms → subarachnoid haemorrhage. Tolvaptan slows progression in selected patients.

A group of immune-mediated diseases of the glomerulus presenting along a spectrum from nephritic (haematuria, hypertension, oliguria, mild proteinuria — active inflammation) to nephrotic (heavy proteinuria, hypoalbuminaemia, oedema). The crucial recognitions are rapidly progressive (crescentic) GN — a renal emergency — and matching the syndrome to its commonest cause. Diagnosis usually needs a renal biopsy.

The triad of heavy proteinuria (>3.5 g/24 h), hypoalbuminaemia and oedema, with hyperlipidaemia. In children it is almost always minimal change disease (steroid-responsive); in adults think membranous nephropathy, FSGS, diabetic nephropathy and amyloid. The complications that get tested are thromboembolism (lost antithrombin III), infection (lost immunoglobulin) and hyperlipidaemia.

The commonest primary glomerulonephritis worldwide. IgA nephropathy (Berger's disease) presents with visible haematuria 1–2 days after a mucosal infection ('synpharyngitic'). IgA vasculitis (Henoch-Schönlein purpura) is the systemic small-vessel form — purpura, arthritis, abdominal pain and nephritis — predominantly in children (detailed on child_health).

Disorders of plasma sodium, which reflect WATER balance relative to sodium rather than total sodium content. Hyponatraemia is assessed by volume status (hypo-, eu-, hypervolaemic) — the key exam algorithm. The danger of correcting either too fast is osmotic demyelination (central pontine myelinolysis) when over-correcting hyponatraemia, and cerebral oedema when over-correcting hypernatraemia.

Disorders of plasma potassium, both potentially fatal through cardiac arrhythmia. Hyperkalaemia (AKI/CKD, ACEi/ARB/spironolactone, Addison's, rhabdomyolysis, acidosis) is the classic medical emergency with a defined ECG progression and a fixed treatment sequence. Hypokalaemia (GI/renal loss, diuretics, alkalosis, hyperaldosteronism) prolongs the QT and causes U waves.

Disorders of plasma calcium (interpret CORRECTED for albumin). Hypercalcaemia is, in over 90%, primary hyperparathyroidism (community) or malignancy (hospital) — 'bones, stones, abdominal groans, psychic moans'. Hypocalcaemia (hypoparathyroidism, vitamin D deficiency, CKD, pancreatitis) causes neuromuscular irritability (Chvostek/Trousseau). Detailed endocrine causes are on the endocrine page; this card is the renal/acute angle.

Disturbances of blood pH classified as metabolic or respiratory acidosis/alkalosis, read off an arterial/venous blood gas. The high-yield skills are the structured 4-step interpretation, splitting metabolic acidosis by the ANION GAP, and recognising the renal tubular acidoses. Med/Lab-science questions love a gas with a calculated anion gap and a compensation check.

Infection of the bladder/urethra (lower UTI/cystitis), usually by E. coli. The high-yield distinctions are: who needs a culture vs empirical treatment, the antibiotic choice and DURATION (women 3 days, men 7 days — any male UTI is 'complicated'), pregnancy (treat asymptomatic bacteriuria, avoid trimethoprim 1st trimester / nitrofurantoin at term), and catheter-associated UTI.

Infection of the upper urinary tract (renal pelvis and parenchyma), usually ascending from the bladder. It presents with the triad of fever/rigors, loin pain and lower urinary symptoms, and can progress to urosepsis. The critical exam move is recognising an OBSTRUCTED, infected system (a pyonephrosis) — which needs emergency drainage, not just antibiotics.

Stones in the renal tract causing renal/ureteric colic — sudden severe loin-to-groin pain with a restless patient unable to get comfortable. Most are calcium oxalate. Non-contrast CT KUB is the diagnostic gold standard. Management depends on stone size and site (NICE NG118), and the emergency is an obstructed, infected system requiring decompression.

Dilatation of the renal pelvis and calyces (hydronephrosis) from obstruction to urine flow, which may be upper-tract (stone, PUJ obstruction, tumour, retroperitoneal fibrosis) or lower-tract (prostate, urethral stricture, pelvic malignancy, blocked catheter). The priorities are relieving the obstruction, watching for post-obstructive diuresis, and not missing an obstructed infected system.

Non-malignant enlargement of the prostate causing lower urinary tract symptoms (LUTS) from bladder outflow obstruction in older men. Symptoms are voiding (hesitancy, weak stream, terminal dribbling, incomplete emptying) and storage (frequency, urgency, nocturia). Treatment escalates from conservative to an alpha-blocker, then a 5-alpha-reductase inhibitor for large glands, then surgery (TURP).

The commonest cancer in men, usually a peripheral-zone adenocarcinoma. Often indolent and detected via PSA/DRE, but can metastasise to bone (sclerotic lesions, back pain). Risk-stratified by PSA, Gleason/grade group and stage. Management ranges from active surveillance (low-risk) to radical treatment, with androgen deprivation for advanced/metastatic disease.

Malignancy of the bladder, in the UK usually transitional cell (urothelial) carcinoma. The cardinal presentation is PAINLESS VISIBLE HAEMATURIA, which mandates urgent (2-week-wait) referral for cystoscopy. Smoking and occupational aromatic-amine exposure (dye/rubber industry) are major risks; schistosomiasis causes squamous-cell bladder cancer in endemic areas.

Renal cell carcinoma, usually clear-cell, arising from the proximal tubular epithelium. The classic (now uncommon) triad is haematuria, flank pain and a flank mass; most are found incidentally on imaging. It is notorious for paraneoplastic syndromes and for a left varicocoele (left renal vein/IVC involvement). Localised disease is treated surgically; it is relatively chemo/radio-resistant.

An uncommon squamous cell carcinoma of the penis, usually of the glans or prepuce, associated with HPV infection, phimosis and chronic inflammation, lichen sclerosus, smoking, and lack of circumcision. It presents as a non-healing penile lesion/ulcer; inguinal lymph node involvement is the key prognostic factor. Diagnosis is by biopsy at a specialist centre.

Involuntary leakage of urine, classified by mechanism because the type dictates treatment: stress (leak on coughing/exertion — sphincter weakness), urgency/overactive bladder (sudden compelling urge — detrusor overactivity), mixed, overflow (chronic retention) and functional/neurogenic. The high-yield exam point is the type-specific first-line: pelvic-floor training for stress, bladder training for urge.

Twisting of the spermatic cord cutting off the testicular blood supply — a surgical EMERGENCY because the testis infarcts within hours. It classically affects adolescents/young men with sudden severe unilateral testicular pain. The single most important rule: it is a clinical diagnosis and surgical exploration must NOT be delayed for imaging — salvage falls sharply after ~6 hours.

The commonest solid malignancy in young men (20–40), almost always a germ-cell tumour — seminoma or non-seminomatous germ-cell tumour (NSGCT). It presents as a painless, hard testicular lump. Tumour markers (AFP, β-hCG, LDH) aid diagnosis and monitoring. It is highly curable, even when metastatic. Cryptorchidism (undescended testis) is a key risk factor.

The common benign scrotal swellings whose examination findings distinguish them — and flag the few that need action. Hydrocoele = fluid around the testis (transilluminates). Varicocoele = dilated pampiniform plexus veins ('bag of worms', usually left). Epididymal cyst = fluid-filled cyst separate from and above/behind the testis. The key catches: a hydrocoele can hide a tumour, and a right-sided or non-decompressing varicocoele needs imaging.

Infection or inflammation of the prostate (prostatitis), epididymis (epididymitis) or testis (orchitis). The crucial split is the likely organism by age/risk: sexually transmitted (Chlamydia, gonorrhoea) in younger sexually active men vs enteric coliforms (E. coli) in older men/those with urinary tract issues — because it changes the antibiotic. Epididymo-orchitis is the main mimic of testicular torsion.

Two foreskin problems with very different urgency. Phimosis is a non-retractile foreskin (physiological in young boys; pathological from scarring/lichen sclerosus/BXO in older patients). Paraphimosis is a urological EMERGENCY: a retracted foreskin trapped behind the glans forms a constricting band causing painful swelling and, if not reduced, glans ischaemia.

Two ends of the erectile spectrum. Erectile dysfunction (ED) is the persistent inability to achieve or maintain an erection for satisfactory sex — frequently an early marker of cardiovascular disease or diabetes, so it warrants CV-risk assessment. Priapism is the opposite: a prolonged (>4 h) unwanted erection that is a urological EMERGENCY because the ischaemic form causes corporal necrosis and permanent impotence.

A reduced circulating volume, from bleeding, gastrointestinal losses, renal losses, burns, third-spacing or simply not drinking. It is the commonest reversible cause of an FY1 bleep about tachycardia, hypotension or a rising creatinine, and assessing it correctly is a daily task rather than an exam curiosity.