The Nephrotic Syndrome

We talked at length about the nephrotic syndrome today at Parkland; See below for a primer on the diagnosis of his disease.

  1. Establish the diagnosis of nephrotic syndrome vs. nephrotic range proteinuria
    • Check the urinalysis:
      • Sediment: should be bland, except for heavy proteinuria.
      • Look for lipiduria (maltese cross).
      • RBCs suggest membranoproliferative GN (MPGN) or lupus-induced membranous nephropathy.
    • Spot urine protein:creatinine ratio; this estimates the 24h urine protein excretion.
      • Nephrotic-range proteinuria > 3.5 g/day.
    • Renal ultrasound:
      • Large kidneys – think of diabetes, HIV nephropathy, and infiltrative disorders
        such as amyloidosis.
      • Caveat: acute GN can present with large kidneys.
    • Labs should reveal hypoalbuminemia and hyperlipidemia.
      • Syndromes (like diabetes, myeloma) associated with nephrotic-range proteinuria may not be associated with these findings.
    • Hypercoagulability in nephrotic syndrome is most commonly seen in membranous nephropathy and MPGN.
  2. Find the cause of underlying nephrotic-range proteinuria
    • Primary (idiopathic) causes of nephrotic syndrome:
      • FSGS: increasing and most common cause in urban settings and in patients of African descent
      • Membranous (MN): most common cause overall; more prominent in elderly patients
      • Minimal change disease (MCD): most common in children, #3 in adults
      • Membranoproliferative glomerulonephritis (MPGN): can present as nephritic or nephrotic syndrome
    • (Some) Secondary causes:
      • Carcinomas – MN; lymphoma – MCD
      • Heroin – FSGS; gold, penicillamine – MN/FSGS
      • Lupus – MN
      • Diabetes mellitus – Kimmelsteil-Wilson lesions
      • Hep B – MN; Hep C – MPGN
      • AIDS – FSGS collapsing variant
      • Syphilis – MN
  3. Initial Work-up:
    • ANA, Anti-DsDNA, ANCA
    • Hep B, Hep C, cryoglobulins
    • C3, C4, CH50
    • hgb a1c, TSH
    • CBC, vit D, PTH
    • Renal US
    • Consider Biopsy

To learn more, check out the following papers this fantastic article from the Archives of Internal Medicine.