Glomerular haematuria — urine microscopy interpretation and stepwise management

Diagnosis: glomerular-pattern haematuria with nephritic syndrome. The combination of dysmorphic RBCs, red-cell casts, significant proteinuria, oedema and hypertension localises the bleeding to the glomerulus and indicates active glomerular inflammation (nephritic syndrome).^[5]

The pivotal distinction — glomerular vs urological (settled by urine microscopy):

• Glomerular = dysmorphic RBCs (acanthocytes >5%), red-cell casts, proteinuria, brown/cola urine, oedema, hypertension → nephrology work-up (UACR, complement, ANA/ANCA, renal biopsy).
• Urological = isomorphic (intact) RBCs, no casts, little/no proteinuria → urology work-up (CT urogram + cystoscopy).^[5]

This patient's microscopy confirms the glomerular branch. The synpharyngitic timing of the haematuria (concurrent with the sore throat, no latency) is classic for IgA nephropathy.

Differential diagnosis of glomerular haematuria in this age group:

• IgA nephropathy — synpharyngitic macroscopic haematuria, raised serum IgA in 30–50%, persistent microscopic haematuria between episodes.
• Post-streptococcal glomerulonephritis — latency 1–3 weeks after streptococcal throat/skin infection, low C3 (normalises in 6–8 weeks), ASO/anti-DNase B raised.
• Lupus nephritis — young women, rash/arthralgia, low C3 and C4, positive ANA and anti-dsDNA.
• ANCA-associated vasculitis / anti-GBM disease — rapidly progressive GN, pulmonary haemorrhage, positive ANCA/anti-GBM.
• Alport syndrome — family history, sensorineural deafness, ocular signs, progressive renal failure.
• Thin basement membrane disease — isolated microscopic haematuria, normal BP and renal function, benign; not consistent with the nephritic picture here.

Stepwise investigation:

1. Confirm and exclude transient causes — repeat urinalysis and microscopy; exclude infection (urine culture), exercise, trauma and contamination.
2. First-line bloods — U&E/eGFR, FBC, UACR/PCR, coagulation, CRP, blood pressure.
3. Nephrology work-up:
   • Complement C3 and C4 — low C3 (with normal C4) favours post-streptococcal GN; both low favours lupus/MPGN.
   • Serology — ANA, anti-dsDNA, ANCA, anti-GBM, hepatitis B/C, HIV.
   • Serum IgA and ASO/anti-DNase B — to support IgA nephropathy or post-streptococcal GN.
   • Renal ultrasound — assess kidney size, echogenicity and obstruction.
4. Renal biopsy — indicated because of nephritic syndrome, significant proteinuria (UACR 650 mg/g) and hypertension; provides definitive diagnosis and prognosis.

Management:

• General measures — salt and fluid restriction, blood pressure control, monitor urine output and weight.
• Blood pressure control — ACE inhibitor or ARB (e.g. ramipril 2.5–10 mg PO daily or losartan 50–100 mg PO daily) for proteinuria and hypertension; diuretics if needed.
• Oedema/oliguria — loop diuretic (furosemide 20–40 mg PO/IV daily) if volume overloaded.
• Definitive therapy — guided by biopsy: IgA nephropathy with progressive disease may receive corticosteroids; lupus/vasculitis/anti-GBM receive immunosuppression (steroids + cyclophosphamide or rituximab; plasmapheresis for anti-GBM).
• Disposition — urgent nephrology referral; admission if severe hypertension, oliguria, or renal failure.

Why not cystoscopy/CT urogram? Those are for a urological pattern (isomorphic RBCs). A glomerular pattern with red-cell casts points to nephrology, not urology.^[5]