Renal & Urology

Glomerulonephritis

Glomerulonephritis is a pattern of glomerular injury that may present with haematuria, proteinuria, oedema, hypertension or acute kidney injury; active urine sediment with rapidly worsening renal function needs urgent nephrology assessment.

In a nutshell

Glomerulonephritis produces a nephritic, nephrotic or mixed picture. Haematuria plus proteinuria with a rising creatinine is active nephritis until assessed; AKI with these findings needs urgent nephrology referral. Start supportive blood-pressure, fluid and electrolyte care, investigate cause with urine, renal function, serology and imaging, and use biopsy- and subtype-directed immunosuppression rather than a generic steroid regimen.

Classic presentation

Haematuria and proteinuria with hypertension, oedema and a rising creatinine, sometimes with pulmonary or systemic vasculitic features.

Key points

Nephritic: haematuria/active sediment, hypertension, oliguria and reduced filtration.
Nephrotic: heavy proteinuria, hypoalbuminaemia and oedema; mixed patterns occur.
AKI with haematuria and proteinuria without UTI or catheter trauma should trigger acute-nephritis thinking and nephrology referral.
Red-cell casts/dysmorphic red cells support glomerular bleeding; quantify proteinuria rather than relying on dipstick alone.
Biopsy is specialist-led and often guides treatment, but do not delay life-saving treatment in a critically ill pulmonary–renal presentation while waiting for every result.
ACE inhibitor/ARB therapy is supportive and requires review during AKI, hypotension or hyperkalaemia.
Immunosuppression depends on subtype, infection screen, serology, biopsy and severity; do not memorise one regimen for all glomerulonephritis.

First-line investigation

Urinalysis and microscopy, urine protein quantification, creatinine/eGFR and electrolytes, blood pressure/fluid assessment, targeted immunology/infection tests and renal ultrasound.

Management

Recognise acute nephritis

Urgently involve nephrology for AKI with haematuria and proteinuria, rapidly rising creatinine, pulmonary–renal features, severe hypertension, pulmonary oedema, hyperkalaemia or oliguria.^4,2

Characterise urine, kidney function and cause

Quantify proteinuria, examine urine sediment, trend creatinine/eGFR and electrolytes, check blood pressure/fluid status, and obtain targeted serology/infection testing and ultrasound.^4,3,1

Protect the kidney and manage complications

Control fluid overload, blood pressure and electrolytes; use renin–angiotensin blockade for proteinuria only when haemodynamically and biochemically appropriate.^3,5,6

Use biopsy- and subtype-directed treatment

Treat infection or systemic disease and use nephrology-directed corticosteroids or additional immunosuppression only when the cause and severity justify it; use current specialist protocols rather than generic doses.^2,5,6

Monitor relapse, CKD and treatment toxicity

Follow kidney function, urine protein/haematuria, blood pressure, potassium, albumin, infection risk and immunosuppressant toxicity; escalate dialysis or critical care for refractory renal or systemic complications.^4,3,5

Exam traps

Haematuria plus proteinuria in unexplained AKI is not a routine UTI or isolated urological problem.
Normal or abnormal complement is a clue, not a diagnosis; interpret it with ANCA, anti-GBM, ANA, infection testing and biopsy.
ACE inhibitor/ARB therapy reduces proteinuria but is not treatment for active immune inflammation and may be unsafe during haemodynamic AKI.
Pulmonary haemorrhage with AKI is a pulmonary–renal emergency requiring immediate multidisciplinary escalation.
Do not start broad immunosuppression without considering infection-related glomerulonephritis and specialist advice.

Illustrations

Nephritic versus nephrotic patterns of glomerular injuryDiagram contrasting cellular/inflammatory injury producing a nephritic picture with podocyte-predominant injury producing a nephrotic picture.PassFinals · original

Crescent formation in rapidly progressive glomerulonephritisHistology image showing cellular crescent formation within Bowman's space compressing the glomerular tuft.Arunachalam Ramaswami, Thiraviam Kandaswamy, Tholappan Rajendran, Kizh, Wikimedia Commons · CC-BY-2.0

A red cell cast in the urine sediment, indicating glomerular bleeding (nephritic picture).Microscopy image showing dysmorphic red blood cells and a red cell cast, indicating glomerular bleeding.Rian Kabir, Wikimedia Commons · CC-BY-2.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.