Artifactual Hypoglycemia Masquerading as a Medical Emergency: A Diagnostic Pitfall of High-Dose Vitamin C

Severe hypoglycemia prompts emergent intervention, yet not all low glucose readings reflect true hypoglycemia. We present a striking case of extreme artifactual hypoglycemia due to high-dose vitamin C therapy, highlighting the diagnostic challenges and management implications.

A 76-year-old man with metastatic prostate cancer, receiving high-dose vitamin C as part of alternative therapy, presented with worsening malaise, oliguria, and edema. On presentation, despite critically low blood glucose (BG) reading (<20 mg/dL) on both point-of-care glucometer and laboratory testing, the patient remained asymptomatic. Repeated dextrose infusions failed to increase the recorded BG levels, contradicting the expected response in true hypoglycemia. Dialysis, rather than dextrose, ultimately corrected his BG readings. Additionally, his liver enzymes, initially undetectable on presentation, became measurable as dialysis progressed. Further investigation identified markedly elevated vitamin C levels as the interfering substance, affecting both standard glucose and liver enzyme assays, leading to pseudo-hypoglycemia.

This case highlights the impact of high-dose vitamin C on glucose oxidase-based assays, causing pseudohypoglycemia and potentially triggering inappropriate clinical interventions. Also, over-reliance on laboratory values without clinical correlation can be costly and problematic particularly in critically ill patients, emphasizing the need for contextual interpretation of biochemical data. Alternative glucose measurement methods, such as hexokinase assays, may be required in suspected cases.

Clinicians should suspect pseudohypoglycemia when glucose readings are critically low but the patient lacks corresponding symptoms, especially in patients pursuing alternative medicine. Whipple's Triad remains vital in differentiating true hypoglycemia from laboratory artifact, preventing unnecessary escalation of care.