Kidney Week

Abstract: SA-PO512

GOLD MARK "S": A Unique Cause of High-Anion Gap Metabolic Acidosis

Session Information

• Acid-Base, Calcium, Potassium, and Magnesium Disorders: Clinical
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Fluid, Electrolytes, and Acid-Base Disorders

• 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

• Allahrakha, Hassan H., Methodist Dallas Medical Center, Dallas, Texas, United States

Hassan H. Allahrakha, DO

• Hazari, Akash, Methodist Dallas Medical Center, Dallas, Texas, United States

Akash Hazari, MD

• Collazo-Maldonado, Roberto L., Methodist Dallas Medical Center, Dallas, Texas, United States

Roberto L. Collazo-Maldonado, MD, FASN

Introduction

Calcific uremic arteriolopathy (CUA) is a serious disorder characterized by vascular calcifications that can affect patients with advanced chronic kidney disease. Currently, there is no approved therapy for CUA, but sodium thiosulfate (STS) has been used off-label for CUA. Mehta et. Al proposed a new anion gap mnemonic for the 21^st century: GOLD MARK. TS is also a cause of high anion gap metabolic acidosis (HAGMA). We present two cases of STS-induced HAGMA.

Case Description

The first patient was a 58-year-old male with end-stage renal disease (ESRD) who presented with left toe gangrene. He was diagnosed with chronic CUA. He received STS (50 g) and underwent dialysis. Eleven days following admission, he developed HAGMA (anion gap: 27 mEq/L, CO₂: 17 mEq/L). The second patient was a 32-year-old female with ESRD secondary to diffuse proliferative lupus nephritis who was admitted for central retinal artery occlusion. She was diagnosed with a painful ulcer on the right thigh secondary to CUA. She received STS and developed HAGMA during her hospitalization (anion gap: 22 mEq/L). In both cases, HAGMA resolved following discontinuation of STS.

Discussion

The mechanism of how STS causes HAGMA is unknown. It is presumed to be due to oxidation of thiosulfate to sulfate by the liver or intestinal bacteria, which is enhanced in patients with ESRD due to reduced clearance of the medication. A new HAGMA mnemonic has been proposed: GOLD MARK (Glycols [ethylene and propylene], Oxoproline, L-lactate, D-lactate, Methanol, Aspirin, Renal failure, and Ketoacidosis). We propose that STS be considered in the differential diagnosis of HAGMA, and that “S” for STS be added to the end of the mnemonic GOLD MARK.