LBODP023 Popular Supplements Containing Plant Extracts With High Biotin Content Can Severely Impact Parathyroid Hormone (PTH) Measurements Leading To A False Suspicion Of Primary Hyperparathyroidism (PHP).

INTRODUCTION: Biotin interference has been recognised as an important factor to take into consideration when analysing discrepancies in laboratory test results of hormone measurements in a 2020 AACC guideline. 1 Little attention has been given yet to possible interference with compound supplements including plant extracts with high biotin content. CLINICAL CASE: A 64 year old woman has been observed in the outpatient clinic for hypothyroidism and Cushing syndrome resolved with adrenalectomy. Routine laboratory check monitoring vitamine D supplementation revealed parathyroid hormone (PTH) elevation- 138 pg/ml with slightly depressed vitamin D level- 24 ng/ml and calcium and phosphorus within normal limits (Ca- 9.3 mg/dl, Pi-2.88 mg/dl). Vitamin D supplementation has been elevated to 4000 IU per day and the PTH and vitamin D levels re-checked after 3 months. Vitamin D was still deficient- 27 ng/ml, PTH was 129 pg/ml. Two months later the patient was hospitalised to evaluate her post-cushing status and the results of Ca, Pi, PTH and vitamin D were reported to be within the normal ranges. Suspecting biotin interference the patient was advised to re- check the PTH levels in two different laboratories and the results differed significantly and were: 72 pg/ml checked with ECLIA method and 137 pg/ml for CMIA method. Suspecting biotin interference patient's history was re-evaluated for supplements and a compound supplement has been identified containing high quantities of pumpkin seed extract (260 mg/capsule) which contains substantial quantities of biotin. Identification of this confounding factor spared the patient further diagnostic procedures. CONCLUSION: It is useful to consider other non-obvious sources of biotin in the form of compound supplements and plant extracts when encountering conflicting results of hormone measurements.1. AAC Guidance Document on Biotin Interference in Laboratory Tests. Journal of Applied Laboratory Medicine, 2020 May 1;5(3): 575-587. Presentation: No date and time listed