Kidney Week

Abstract: SA-PO0561

Over-the-Counter Vitamin D2 Toxicity from Label Misinterpretation: Severe Hypercalcemia and AKI

Session Information

• Bones, Stones, and Mineral Metabolism: Research and Cases
  October 24, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Bone and Mineral Metabolism

• 502 Bone and Mineral Metabolism: Clinical

Authors

• Jalloul, Youssef, Albany Medical College Division of Nephrology & Hypertension, Albany, New York, United States

Youssef Jalloul, MD

• Monrroy, Mauricio, Albany Medical College Division of Nephrology & Hypertension, Albany, New York, United States

Mauricio Monrroy, MD

• Beers, Kelly, Albany Medical College Division of Nephrology & Hypertension, Albany, New York, United States

Kelly Beers

• Faddoul, Giovanni, Albany Medical College Division of Nephrology & Hypertension, Albany, New York, United States

Giovanni Faddoul, MD

Introduction

Vitamin D toxicity is a rare but potentially life-threatening condition characterized by severe hypercalcemia, acute kidney injury (AKI), and multiorgan dysfunction. The tolerable upper intake level established by the Institute of Medicine is 4,000 IU/day, with toxicity generally associated with sustained intake exceeding 10,000 IU/day. High-dose vitamin D supplements, including 50,000 IU ergocalciferol capsules, are available online without a prescription, bypassing clinical oversight. Supplement labeling conventions can be misinterpreted, leading to catastrophic dosing errors. We present a case of severe vitamin D2 toxicity resulting from label misinterpretation.

Case Description

A 66-year-old male with heart failure with preserved ejection fraction and coronary artery disease presented with severe hypercalcemia (calcium 14.9 mg/dL) and AKI (creatinine 3.61 mg/dL; baseline ~1.0 mg/dL). Workup revealed 25-hydroxyvitamin D >120 ng/mL, 1,25-dihydroxyvitamin D of 438 pg/mL (reference ≤81.5), intact PTH of 4.5 pg/mL, PTHrP of 13 pg/mL, and negative serum protein electrophoresis. The patient had purchased ergocalciferol 50,000 IU capsules online. The label listed each pill as "6,250% of daily value." He misread the comma as a decimal point (6.250%). Believing he was taking a fraction of the recommended intake, he took four capsules daily (200,000 IU/day) for nine months. He was also taking losartan-hydrochlorothiazide 100/12.5 mg; the thiazide was discontinued, given its calcium-retaining properties. Treatment included intravenous fluids, calcitonin, zoledronic acid, denosumab, and prednisone. Calcium decreased to 9.9 mg/dL and creatinine improved to 2.1 mg/dL.

Discussion

This case illustrates two public health hazards. First, vitamin D2 supplements are available online without a prescription, enabling unsupervised pharmacologic dosing. Second, labeling conventions can be dangerously misleading. The expression "6,250%" was misread as "6.250%" due to confusion between the comma as a thousands separator and a decimal point (format varies across cultures). This transformed what the patient believed to be a trivial supplement into a toxic dose. This case underscores the need for clearer labeling standards such as not using a comma or other separator when dealing with numbers that are not decimals and regulatory consideration of restricting vitamin D2 formulations to prescription-only.

Acknowledgment

OpenEvidence (OpenEvidence, Inc.), an AI-powered medical knowledge assistant, was used to assist with literature review, data interpretation, and manuscript drafting. All content was reviewed, verified, and edited by the authors, who take full responsibility for the accuracy and integrity of the work.