Hypernatraemia
How a serum sodium above 145 mmol/L means a water deficit, how to find why it happened, and how to correct it without causing cerebral oedema.
Checked against sourcesVerified 28 October 2026
Renal and genitourinary medicine
Diseases of the kidneys and urinary tract: fluid, electrolyte and acid-base disorders, kidney injury and chronic kidney disease.
Introduction
Renal and genitourinary medicine covers the kidneys, the water, salt and acid balance they control, and the urinary and male genital tract. Many of its problems are found first on a blood test, so this section starts with the electrolytes before it moves to the organs.
The order follows the way a clinician works: first the electrolyte and acid-base disturbances that change the heart and brain within hours, then acute kidney injury, then the glomerular syndromes, then the structural diseases (stones, cysts, obstruction), infection and bladder function, the male genital tract, and finally the urological cancers.
Every topic uses the same layout: a short summary, what you should be able to do afterwards, the mechanism, the clinical picture, tests, treatment and the traps. Doses, thresholds and correction rates are checked against named guidelines and shown with their source, because guidelines and countries sometimes differ.
How to study renal and genitourinary medicine
Learn the electrolyte topics as pairs and as rules: why a fast correction of sodium harms the brain, and why potassium is treated first by protecting the heart. The acid-base topic rewards practice with a stepwise method on real blood gases rather than memorising lists.
For acute kidney injury and the glomerular syndromes, think in three steps: is the problem before the kidney, in the kidney or after it, then what does the urine show, then what is the treatable cause. The urine sediment and the protein level sort most diagnoses.
Learn the emergencies as pathways: severe hyperkalaemia, symptomatic hyponatraemia, the obstructed infected kidney, torsion of the testis and spinal cord compression from prostate cancer. Practise saying the first three actions aloud, and use the check-yourself questions at the end of each topic a few days later.
This section links to cardiology (diuretics, hypertension), endocrinology (calcium, diabetes insipidus), infectious disease and oncology, so follow the related links. Content here is for study and does not replace local protocols or a senior clinician's judgement.
Contents by part
The topics below are in teaching order. Each part builds on the one before it.
- Water, sodium and potassium. Start with the two electrolytes that decide most renal emergencies: how too much or too little water and sodium harm the brain, and how potassium changes the heart.
- Calcium, magnesium and acid-base. The remaining electrolytes, then the stepwise reading of acid and base disturbances and the renal tubular acidoses.
- Kidney injury and diuretics. Acute kidney injury as a pathway (before, in or after the kidney), and the drugs that act along the nephron.
- Glomerular disease. The two glomerular syndromes: the nephritic picture with blood and casts, and the nephrotic picture with heavy protein loss.
- Stones, cysts and obstruction. Structural problems of the kidney and urinary tract: stones, cysts and blocked drainage.
- Infection and bladder function. Urinary infection from cystitis to pyelonephritis, and the disorders of storing and emptying urine.
- Prostate, penis and scrotum. Male genitourinary problems, from the acute scrotum to prostate enlargement and erectile dysfunction.
- Urological cancers. The four common cancers of the urinary and male genital tract, ending with the approach to haematuria.
Topics
Hyponatraemia
Low serum sodium: how to find the cause, judge severity, and correct it safely.Checked against sourcesVerified 28 October 2026Hyperkalaemia
Elevated serum potassium: why it matters, how it changes the ECG, and how to stabilise and remove it.Checked against sourcesVerified 28 October 2026Hypokalaemia
Low serum potassium: causes, assessment with urine potassium and acid-base status, ECG changes, and safe replacement.Checked against sourcesVerified 28 October 2026Fluid and electrolyte therapy
Adult fluid and electrolyte therapy: assessing volume status, resuscitation and maintenance IV fluids, crystalloid choice, correcting common disorders.Checked against sourcesVerified 31 October 2026Diabetes insipidus and polyuria
Polyuria from central and nephrogenic diabetes insipidus: causes, water-deprivation testing, and management, with cross-checks to endocrinology and.Checked against sourcesVerified 31 October 2026
Hypercalcaemia
What makes blood calcium rise, how it harms kidneys, bones and brain, and how to bring it down safely.Checked against sourcesVerified 28 October 2026Hypocalcaemia
Low blood calcium: causes, clinical features, ECG changes, diagnosis and treatment, including low-resource settings.Checked against sourcesVerified 28 October 2026Hypomagnesaemia and hypermagnesaemia
Low and high serum magnesium: causes, effects, refractory hypokalaemia and hypocalcaemia, and treatment.Checked against sourcesVerified 28 October 2026Acid-base disorders and renal tubular acidosis
Stepwise acid-base interpretation: pH, primary process, compensation, anion gap, osmolar gap, renal tubular acidosis and mixed disorders.Checked against sourcesVerified 28 October 2026Hypophosphataemia, hyperphosphataemia and CKD mineral and
Low and high serum phosphate, hypophosphataemia and CKD-mineral and bone disorder: causes, effects, vitamin D, PTH and phosphate binders.Checked against sourcesVerified 31 October 2026Acute kidney injury
Rapid loss of kidney function: KDIGO definition and staging, causes, urinary indices, assessment, complications, and management.Checked against sourcesVerified 28 October 2026Diuretics
Classes of diuretics, their sites and mechanisms in the nephron, indications, dosing, adverse effects, resistance and how to choose.Checked against sourcesVerified 28 October 2026Chronic kidney disease
Chronic kidney disease: staging by eGFR and albuminuria, causes, complications, progression, and treatment.Checked against sourcesVerified 31 October 2026Dialysis and kidney transplantation
Dialysis and kidney transplantation: indications, modalities, access, complications, transplant eligibility, immunosuppression and rejection.Checked against sourcesVerified 31 October 2026Contrast nephropathy, rhabdomyolysis and acute tubular
Contrast-associated and drug- or pigment-induced acute tubular injury: mechanisms, risk stratification, prevention and management.Checked against sourcesVerified 31 October 2026Acute interstitial nephritis and tubulointerstitial disease
Acute inflammation of kidney tubules and interstitium, usually drug-related: causes, urine sediment, steroids, and analgesic nephropathy.Checked against sourcesVerified 31 October 2026Renovascular disease and renal artery stenosis
Renal artery stenosis from atherosclerotic and fibromuscular disease: how it causes hypertension, flash pulmonary oedema and ACE inhibitor acute kidney.Checked against sourcesVerified 31 October 2026Nephritic syndrome and glomerulonephritis
Blood and protein in the urine with pressure and swelling: what nephritic syndrome is, its glomerular causes, and how it is investigated and treated.Checked against sourcesVerified 28 October 2026Nephrotic syndrome
Heavy proteinuria, low albumin, swelling and high lipids: what nephrotic syndrome is, why each feature happens, its causes, and how it is treated.Checked against sourcesVerified 28 October 2026Haemolytic uraemic syndrome and thrombotic microangiopathy
A thrombotic microangiopathy pattern: STEC-associated and complement-mediated atypical HUS, TTP contrast, diagnosis, and treatment.Checked against sourcesVerified 31 October 2026Nephrolithiasis
How kidney stones form, present and are treated: types, diagnosis, pain relief, drainage, surgery, and prevention.Checked against sourcesVerified 28 October 2026Polycystic kidney disease
Autosomal dominant and recessive polycystic kidney disease: cyst growth, complications, diagnosis, blood pressure control, tolvaptan, and low-resource care.Checked against sourcesVerified 28 October 2026Hydronephrosis and urinary tract obstruction
Obstruction anywhere from kidney tubules to urethra: why it swells the kidney, symptoms, tests by level, how to relieve it, and when it is an emergency.Checked against sourcesVerified 28 October 2026Urinary tract infection, cystitis and pyelonephritis
Definitions, diagnosis and treatment of urinary tract infections: cystitis, pyelonephritis, asymptomatic bacteriuria and complicated and recurrent forms.Checked against sourcesVerified 28 October 2026Urinary incontinence and interstitial cystitis
Stress, urgency, overflow, functional and mixed urinary incontinence, with evaluation, treatment and bladder pain syndrome.Checked against sourcesVerified 28 October 2026Acute urinary retention and lower urinary tract obstruction
Sudden inability to void: causes, catheterisation, post-obstructive diuresis and urethral stricture.Checked against sourcesVerified 31 October 2026Prostatitis and chronic pelvic pain
Acute and chronic bacterial prostatitis and chronic pelvic pain syndrome: definitions, diagnosis, treatment and relation to UTI.Checked against sourcesVerified 31 October 2026Scrotal swelling, testicular torsion and epididymitis
Approach to scrotal swelling, testicular torsion and epididymitis: causes, red flags, examination, tests, treatment and low-resource care.Checked against sourcesVerified 28 October 2026Erectile dysfunction
Why erections fail, how to find the cause and how to treat it: physiology, risk factors, tests, drug and device therapy, surgery and low-resource care.Checked against sourcesVerified 28 October 2026Benign prostatic hyperplasia
Benign, non-cancerous growth in the transition zone of the prostate that blocks urine flow; symptoms, diagnosis, treatment, and when surgery is needed.Checked against sourcesVerified 28 October 2026Male infertility and hypogonadism
Causes, evaluation and treatment of male infertility, varicocele and hypogonadism, with semen analysis standards and testosterone thresholds.Checked against sourcesVerified 31 October 2026Genitourinary trauma and priapism
Renal, ureteric, bladder, urethral and penile injuries and ischaemic priapism: how they present, how to assess them, and the first steps in management.Checked against sourcesVerified 31 October 2026Prostate cancer
How prostate cancer is detected, staged and treated, from PSA and MRI to active surveillance, surgery, radiotherapy, hormones and advanced disease.Checked against sourcesVerified 28 October 2026Bladder cancer
Bladder cancer: painless visible haematuria, cystoscopy and TURBT, with stage-based care from intravesical BCG to cystectomy and immunotherapy.Checked against sourcesVerified 28 October 2026Renal cell carcinoma and the approach to haematuria
Clear cell and other renal cell cancers, from risk and pathology to staging, surgery and systemic therapy, plus a practical approach to haematuria.Checked against sourcesVerified 28 October 2026Testicular cancer
Testicular cancer in young men: types, tumour markers, staging, orchidectomy, chemotherapy and cure.Checked against sourcesVerified 28 October 2026Benign renal tumours and upper tract urothelial carcinoma
Benign kidney tumours, cysts and imaging categories, plus upper tract urothelial carcinoma from presentation through nephroureterectomy and adjuvant therapy.Checked against sourcesVerified 31 October 2026Penile and urethral cancer
Penile and urethral cancer: risk factors, HPV and phimosis, premalignant lesions, staging, organ-sparing surgery, nodal and systemic management.Checked against sourcesVerified 31 October 2026