SHM Converge Scientific Abstract ePoster Gallery-Cortisol Assay Interference With Biotin Supplementation During Pembrolizumab Use

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Northwell Health describes itself as New York State’s largest health care provider and private employer, committed to high-quality clinical care, medical education, research, health promotion, and care for all regardless of ability to pay. It serves the region through 23 hospitals, more than 700 outpatient facilities, and a large network of affiliated physicians.<br /><br />The document then presents a clinical case about cortisol assay interference caused by biotin supplementation during pembrolizumab (Keytruda) treatment. A 63-year-old woman with triple-negative metaplastic breast cancer began neoadjuvant chemotherapy including pembrolizumab. Her baseline thyroid, liver, and cortisol tests were normal, but one month later her free cortisol appeared very low, raising concern for immune-related adrenal insufficiency, a known but uncommon adverse effect of anti-PD1 therapy.<br /><br />Further review revealed she had started taking 10,000 mcg/day of biotin for hair loss after treatment began. Once biotin was stopped, her cortisol level normalized, confirming that the abnormal result was due to biotin interference rather than true adrenal insufficiency.<br /><br />The case highlights several teaching points: immune checkpoint inhibitors can cause serious endocrine immune-related adverse events, but clinicians must consider all possible causes of abnormal labs and symptoms before interrupting life-saving cancer therapy. Biotin can interfere with immunoassays, producing falsely low results in sandwich assays and falsely high results in competitive assays. A thorough medication history, including over-the-counter supplements, is essential to avoid misdiagnosis, unnecessary workup, and patient stress.

Asset Subtitle

Sundeep Kaur

Meta Tag

Author List Kit Cheng, Sundeep Kaur

Category Clinical Vignettes

Concept PD-1 Inhibitor

Concept Immune-Related Adverse Event

Concept Adrenal Insufficiency

Concept Biotin

Concept Pembrolizumab

Distinguished Non-Finalist

Presenter Organization Zucker School of Medicine Northwell NS/LIJ

Presenting Author Sundeep Kaur

Track Adult

Keywords

Northwell Health

cortisol assay interference

biotin supplementation

pembrolizumab

immune checkpoint inhibitor

adrenal insufficiency

immunoassay interference

endocrine adverse event

breast cancer

medication history

PD-1 Inhibitor

Immune-Related Adverse Event

Adrenal Insufficiency

Biotin

Pembrolizumab