AKT · Renal & urology/Glomerular diseaselow yield

IgA nephropathy & IgA vasculitis

IgA immune-complex deposition in the glomerular mesangium (nephropathy) / small vessels (vasculitis/HSP)

Overview

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).

Recognise

IgA nephropathy: visible (macroscopic) haematuria 1–2 DAYS after a URTI/mucosal infection ('synpharyngitic') — contrast with post-strep GN (1–2 weeks); young adults
IgA vasculitis (HSP): palpable purpura over buttocks/extensor legs + arthralgia + colicky abdominal pain + nephritis, often after an URTI (mainly children)
Ranges from isolated haematuria to nephritic syndrome/CKD; raised serum IgA in some

Red flags

Nephritic syndrome with rising creatinine → RPGN risk → nephrology/biopsy
HSP with severe abdominal pain → intussusception/GI bleed; significant proteinuria/renal involvement → monitor and treat

Differentials & how to tell them apart

Post-streptococcal GNhaematuria 1–2 WEEKS after strep, low complement, ASO titre — IgA is 1–2 days after

Thin basement membrane disease / Alporthereditary haematuria; Alport adds deafness/ocular signs

Other small-vessel vasculitisANCA-associated — different serology

Investigations

Urinalysis (haematuria ± proteinuria), U&Es/eGFR, BP; renal biopsy (mesangial IgA deposits) for significant/progressive disease; for HSP — clinical (palpable purpura + the features), urinalysis/BP to detect nephritis. Exclude other causes of haematuria.

Management

Supportive ACEi/ARB + BP control; immunosuppression for progressive disease

1Recognise IgA nephropathy (visible haematuria 1–2 days after a URTI) vs HSP (palpable purpura + arthritis + abdominal pain + nephritis). Manage proteinuria/BP with an ACE inhibitor/ARB; monitor renal function.Gate: Progressive disease (rising creatinine, persistent significant proteinuria, RPGN) → renal biopsy and immunosuppression; HSP needs urinalysis/BP follow-up to catch delayed nephritis.
2Add corticosteroids/immunosuppression for progressive IgA nephropathy or severe HSP; manage CKD long-term. Full paediatric HSP detail is on the child_health page.

Supportive: BP control + ACE inhibitor/ARB to reduce proteinuria — first-line for IgA nephropathy with proteinuria/hypertension; slows progression

Corticosteroids/immunosuppression for progressive disease — for persistent proteinuria/declining function despite optimal supportive care (specialist)

HSP: supportive, analgesia; monitor BP/urinalysis — mostly self-limiting; corticosteroids for severe GI/renal disease (specialist)

Manage CKD complications — long-term in progressive disease

Key points

Visible haematuria 1–2 DAYS after a URTI = IgA nephropathy (Berger's) — vs post-strep GN 1–2 WEEKS after. Systemic IgA = HSP (purpura + arthritis + abdo pain + nephritis, mainly children). Treat proteinuria/BP with ACEi/ARB; immunosuppression for progressive disease.

Monitor & prognosis

Haematuria/proteinuria, eGFR, BP; HSP — urinalysis/BP for delayed nephritis.

Variable — many stable, a minority progress to ESRD; childhood HSP usually self-limits.

Source: KDIGO; cross-ref child_health (HSP)