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Abstract: FR-PO577

Hypokalemic Tetraparesis as First Manifestation of MGRS

Session Information

  • Trainee Case Reports - III
    October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Lepori, Nicola, Ospedale Brotzu, Cagliari, Italy
  • Floris, Matteo, Ospedale Brotzu, Cagliari, Italy
  • Angioi, Andrea, Ospedale Brotzu, Cagliari, Italy
  • Cao, Riccardo, Ospedale Brotzu, Cagliari, Italy
  • Atzeni, Alice, Ospedale Brotzu, Cagliari, Italy
  • Asunis, Anna Maria, Ospedale Brotzu, Cagliari, Italy
  • Piras, Doloretta, Ospedale Brotzu, Cagliari, Italy
  • Cabiddu, Gianfranca, Ospedale Brotzu, Cagliari, Italy
  • Pani, Antonello, Ospedale Brotzu, Cagliari, Italy
Introduction

Renal potassium wasting is a frequent cause of hypokalemia; it can be consequence of medications, endogenous hormone production, inherited or acquired renal tubular defects

Case Description

A 50 y/o woman was admitted to our Hospital with limb weakness, muscle cramps progressing to tetraparesis, associated with severe hypokalemia (1,6 mEq/L). She denied diarrhea or vomiting; pharmacologic and past medical history were unremarkable. Labs showed normal renal function, hyperchloremic metabolic acidosis, urinary potassium wasting (88 mmol/24h) and alkaline urine. A diagnosis of hypokaliemic tetraparesis due to distal renal tubular acidosis (type 1 RTA) was made. IV NaHCO3 and KCl replacement resolved the tetraparesis. Further investigations were made: SPEP showed a IgMK monoclonal protein, ANA (1:640) and ENA-SSA were positive (689 U/ml) while antiDNAds were negative. At that time, she rejected a renal biopsy and any follow-up. Two months later, she was admitted to our Department with hypertension (170/90 mmHg) and swelling. Labs showed normal kidney function, hypokalemia, slightly increased CRP levels. Urinalysis revealed microscopic hematuria and proteinuria (3.6 g/24h). Serology revealed very low C3 and C4, positive ANA (1:320), ENA-SSA (314 U/ml), type 1 cryoglobulins (IgMk). Suspecting an MGRS, a renal biopsy was performed: light microscopy showed an MPGN pattern with coarse pseudothrombi and a diffuse interstitial infiltration of lymphomonocytes, kappa+. IF was coherent with serology, showing IgMK (+++) and C3 (++) subendothelial deposits, and kappa+ cytoplasmic droplets in proximal tubules. Type 1 cryoglobulinemia and kappa light chains induced chronic tubular interstitial nephritis (resulting in type 1 RTA) was diagnosed. After three courses of dexamethazone, rituximab and cyclophosphamide, microscopic hematuria disappeared, proteinuria improved to 0,15 g/24h and serum potassium levels persisted steady without potassium supplements

Discussion

We described an unusual presentation of MGRS, with severe hypokalemia due to diffuse tubular injury mediated by kappa light chain, followed by a full blown type 1 cryoglobulinemia. Searching for a monoclonal protein should be an essential part investigating an acquired tubular disfunction