Atypical Thyroid Function Tests and Thyroid Hormone Resistance

Cureus. 2021 Jul 12;13(7):e16328. doi: 10.7759/cureus.16328. eCollection 2021 Jul.

Abstract

Clinical interpretation of thyroid labs is usually straightforward. However, there are rare instances when the atypical profile of thyroid labs warrants systematic investigation to determine the underlying cause. We report the case of a 90-year-old Caucasian male with a chronic history of atrial fibrillation with chronic pacemaker dependence who presented with significantly elevated free thyroxine level (>7.77 ng/dL) but normal thyroid-stimulating hormone level (2.15 µIU/mL). After ruling out pituitary tumors and artifactual errors due to lab interference, the diagnosis of thyroid hormone resistance was made.

Keywords: artifactual lab interference; atypical thyroid function tests; autosomal dominant; thyroid hormone receptor beta; thyroid hormone resistance.

Publication types

  • Case Reports