3 Aug 2021

4/19/21: Anti-phospholipase 2 Receptor Membranous Nephropathy

PGY4 Julian Hirschbaum presented a case of a 73 year old male with history of ischemic cardiomyopathy, HFrEF 55%, CAD s/p stent in LAD, HTN, BPH, and GERD presents with 1 day of worsening abdominal pain, nausea and vomiting.  The patient has had 8 month history of intermittent diffuse abdominal pain that is now acutely worsened.  He rates it as 9/10 in severity and is exacerbated by food and medication and associated with daily nausea and NBNB emesis.  +9 months of whole body swelling.  +DOE after 1 block of ambulation and occasional SOB wen lying supine.

Home Meds: ASA 81mg qday, Atorvastatin 80mg qday, Carvedilol 25mg BID, Amlodipine 5mg qday, Clopidogrel 75mg qday, Omeprazole 20mg qday

SH: Born in Jalisco, Mexico.  Incarcerated for 2 years.  Remote history of tobacco and alcohol use.  No history of illicit drugs.

Vitals: T 36.8, HR 73, RR 18,  BP 161/82, O2 sat 99% on RA

Physical Exam: mild bilateral crackles in lower lung fields, normal cardiac exam, mildly distended abdomen, 3+ pitting edema to thighs, +pitting edema in b/l UE, scrotal sac diffusely swollen

CBC: WBC 7.2> Hb 13.4/Hct 38.1 <Plt 169 (MCV 91.5, RDW 12.2%)

CMP:

Na 137/K 4.4/Cl 105/HCO3 25/BUN 24/Cr 2.27<Glucose 123

ALP 84>T.protein 4.3/Albumin 1.9/AST 22/ALT 12/Tbili 0.2/Dbili <0.2

Ca 7.7. Mg 2.2, Phos 4.4

Coags: PT 13.5, INR 1.04

Infectious workup including BCx, UCx, procal, RPR, HIV, hepatitis panel negative.

Renal workup:

  • UA with 300 protein, 250 glucose, trace ketones and large blood (11-25 RBCs); negative leuk/nitrites
  • FeNa: 7.1%
  • FeUrea: 109.3%
  • U24H protein: 10.75g/24 hours
  • Renal US: normal echogenicity in the kidneys, small bilateral pleural effusions
  • SPEP: no monoclonal proteins identified by immunofixation
  • UPEP: abnormal band in the beta region
  • K/L: 3.27
  • Anti-PLA2R positive

Rheum labs negative for ANA, ANCA, Anti-GBM and normal complement levels.

Renal Biopsy: Membranous nephropathy, stage 2 of 4; PLA2R staining is positive

Treatment: Patient started on IV diuresis and symptomatically improved. Discharged with follow up with renal.

Teaching points:

  1. Membranous nephropathy is characterized by basement membrane thickening and the presence of electron dense deposits across the GBM.
  2. In determining the etiology of MN, secondary causes such as malignancy, SLE, drugs and infection must be ruled out.
  3. Primary MN is now considered a renal-limited autoimmune disease, with antibodies against PLA2R identified in 70-80%.
  4. Treatment of primary MN relies on use of immunosuppressive agents such as glucocorticoids, alkylating agents, calcineurin inhibitors and the anti-CD20 monoclonal antibody, Rituximab.

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