Abstract: PO1175
Mind the Gap: An Anion Gap of 52 Fully Explained
Session Information
- Mineral Homeostasis and Acid-Base Disorders: Clinical
November 04, 2021 | Location: On-Demand, Virtual Only
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolyte, and Acid-Base Disorders
- 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Avula, Uma Mahesh R., The University of Mississippi Medical Center, Jackson, Mississippi, United States
- Harris, Liliia, The University of Mississippi Medical Center, Jackson, Mississippi, United States
- Shafi, Tariq, The University of Mississippi Medical Center, Jackson, Mississippi, United States
- Dossabhoy, Neville R., The University of Mississippi Medical Center, Jackson, Mississippi, United States
Introduction
The Anion Gap (AG) remains the main clinical tool to elucidate acid-base disturbances in patients with metabolic acidosis. We present a case with an extremely elevated AG of 52 mmol/L, and describe our search for its biochemical explanation.
Case Description
A 66-year-old female was admitted with loss of consciousness, shock, and severe acute kidney injury. She had type 2 diabetes mellitus, treated with metformin. At presentation, she had an AG of 52 mmol/L and osmolal gap of 34 mOsm/kg. Her arterial blood gas showed: pH <7, HCO3 7.5 mmol/L, pCO2 16 mm/Hg. Phosphorus level was unusually high, 21.3 mg/dL, with unknown etiology. There was no history of enema or laxative use. A significant contributor of AG was lactate at 14.5, given her history of metformin use. Urine drug screen was positive for amphetamines. The volatile alcohol panel was positive for acetone; methanol, ethanol, ethylene glycol and isopropyl alcohol were not detected. Continuous venovenous hemofiltration (CVVH) was initiated. After 3 days, renal function started recovering, lactate and phosphorus levels normalized and AG closed. The patient did not need CVVH thereafter. Two months later, the patient was discharged to a nursing facility in a stable condition.
Discussion
Extremely elevated AG of 52 in this patient can be explained by a rise in concentrations of organic acid anions, lactate, ketoacids, hyperphosphatemia, and retention anions.
Explanation of the high AG: The Figure describes the calculation of AG. In this patient, phosphate was a major contributor to the AG.