Glomerulonephritis (GN)

Inflammatory condition of the kidney.

• Typically presents with AKI, hypertension, proteinuria and hematuria.

• Nephritic range proteinuria is generally considered less than nephrotic range (UPC >2 mg/mg, or protein excretion >40 mg/m²/h), but it can vary

• GNs are considered auto-immune in nature, either by reacting directly to antigens in the kidney or systemically (secondary GN) or experiencing some dysregulation of normal immunologic response.

• They are graded by the rate of progression when it comes to defining urgency

  • Acute GN (GN that has injured the kidneys) along with systemic symptoms

  • Rapidly progressive GN - basically any acute GN that causes your kidneys to fail quickly (days to weeks). Higher priority for intervention like steroids or possibly a biopsy

  • Recurrent, episodic GN - Typically presents like a GN but recovers in between (specifically looking at resolution/normalization of proteinuria, AKI and any hypertension). Sometimes with enough episodes, some or all of these features may not recover. Think IgA nephropathy, recurrent SLE nephritis flares, etc.

  • Chronic GN - GN that may not show kidney dysfunction except in proteinuria, hematuria and HTN. Cr may stay normal for years before it starts to decline.

Workup/Diagnosis

• KFP with signs of AKI: high Cr, K; sAlb rarely low

• UA: RBCs, RBC casts, proteinuria (mainly non-nephrotic)

• Abs to Strep Antigens: ASO (throat), anti-DNAaseB (skin), Streptozyme (measures 5 types of Abs, includes ASO and ant-DNAaseB)

• Serum complements: C3 low, C4 normal or low

• Negative: ANA, ANCA

• Biopsy

  • in case of rapid rise in sCr; may cause crescentic GN

  • if diagnosis unclear

  • typical finding: large subepithelial immune complexes i.e. “humps” on EM; IgG + C3 on IF

Treatment

• Supportive

• If severe course, may need immunosuppression

• Manage HTN: low salt intake, diuretics, antihypertensives

Prognosis/Follow up

• C3 and C4 normalize in 6-8 weeks, need to be checked then

• Post-infectious GN: if Strep not found, but course is similar, could assume other infection caused GN

• Microhematuria can persist ~6-12 months

• If C3/C4 not normalized needs further testing: i.e. SLE, MPGN/C3GN, genetic disorders of the complement system

• PSGN usually does not recur

• PSGN can be subclinical and patients may present years later as CKD of unclear etiology

• Abx for Strep (likely not beneficial for existing GN):

  • Early Abx to treat throat/skin may decrease risk or severity of GN;

  • To eradicate:

    • during GN if Strep still detected

    • in communities with high PSGN incidence