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Abstract: FR-PO700

Peculiar Case of Life Threatening Hypokalemia

Session Information

Category: Trainee Case Report

  • 902 Fluid and Electrolytes: Clinical

Authors

  • Peleg, Yonatan A., Columbia University Medical Center, New York City, New York, United States
  • Ahn, Wooin, Columbia University Medical Center, New York City, New York, United States
Introduction

Severe hypokalemia causes muscle weakness and cardiac arrhythmias. We present a case of life threatening hypokalemia due to RTA.

Case Description

32-year-old woman presented with subacute weakness and muscle pain. She denied personal or family history of nephrolithiasis, autoimmunity, malignancy, deafness, growth retardation, fracture, anorexia, diarrhea, medication, illicit drug or heavy metal exposure. EKG showed QTc 756 ms and U waves. Labs revealed creatinine 0.75 mg/dL, K+ 1.7 mEq/L, Mg2+ 2.9 mg/dL, HCO3- 13 mEq/L, pH 7.28, urine pH 7.5, trace urine albumin, urine anion gap 7 mmol/L and urine osmolal gap 39 mOsmol/kg. 24 hour urine showed K+ 133 mEq, calcium 863 mg, phosphate 1150 mg, protein 690 mg and citrate <60 mg. Her imaging was notable for nephrocalcinosis. Calcidiol was 6.5 ng/ml and peak CPK was 5145 U/L. PTH decreased from 205.8 pg/mL (calcium 7.5 mg/dL) to 42.9 pg/mL (calcium 8.9 mg/dL). Chest imaging without hilar adenopathy. SS-A and SS-B antibodies were negative. Genetics screen was obtained and pending. After 880 mEq of K, her plasma K reached > 4. K citrate was started at 120 mEq daily and her acidosis resolved after 3 days. She was discharged with 80 mEq of K Citrate daily with stable chemistries.

Discussion

Distal RTA (dRTA) is characterized by inability to secrete H+ in the distal tubule. It is associated with hypokalemia if non-voltage mediated. It can lead to hypercalciuria, hyperphosphaturia, hypocitraturia and consequent nephrocalcinosis. dRTA yields alkaline urine but urinary pH is maintained <6.5 because bicarbonate is not significantly lost. However, this patient had urinary pH 7.5 and tubular proteinuria suggesting proximal tubule injury. The etiology of the patient’s proximal tubule injury is unclear, but the hypovitaminosis D is glaring. Overall, this case represents a peculiar presentation of RTA, with likely long-standing dRTA and sub-clinical nephrocalcinosis coupled with proximal injury resulting in life threatening hypokalemia. Clinicians should consider RTA as the cause of hypokalemia.

Nephrocalcinosis