IgA nephropathy

(CJASN 2017;12:677; AJKD 2021;78:429)

• Most common cause of GN; ♂ pred; peak incidence 20–30s; can also be post-infectious
• Wide range of clinical presentations: asx hematuria (30–40%), gross hematuria ~1–3 d after URI (10–15%), chronic GN (10%), nephrotic syndrome (5%), RPGN (<5%)
• Though clinical presentation can be highly suggestive, definitive dx only w/ bx
• Prognosis: ↑Cr, HTN, proteinuria a/w poor prog. (AJKD 2012;59:865). 20–40% ESRD w/in 20 y.
• Rx: ACEI/ARB; if persistent proteinuria (> 1g/d), clinical trial enrollment or shared decision for steroids, consider SGLT2i (NEJM 2020;383:1436); ± cytotoxic Rx for GN; ? fish oil

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IgA vasculitis

(formerly Henoch-Schönlein purpura [HSP]) (Rheumatol 2019;58:1607)

• IgA-mediated small-vessel vasculitis w/ predilection for skin, GI tract, and kidneys
• Epidemiology: incidence 140/million/y; ♂ >♀, children >adults, winter >summer
• May develop ~10 d after onset of upper resp infx or after drug exposure
• Clinical manifestations of IgA vasculitis
• Dx studies: skin bx w/ immunofluorescence → leukocytoclastic vasculitis w/ IgA and C3 deposition in vessel wall; renal bx → mesangial IgA deposition
• Treatment: often self-limiting over 4 wk; steroids ± DMARDs for renal or severe disease