ABSTRACT
The hypothalamic–pituitary–thyroid (HPT) axis is responsible for the regulation and production of thyroid hormone (TH). The hypothalamus secretes thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to produce thyroid-stimulating hormone (TSH), which causes the production and release of thyroid hormones (TH). The two forms of TH are thyroxine (T4) and triiodothyronine (T3). When assessing thyroid function, lab tests can be categorized into those that assess the HPT axis: TSH, free T3, free T4, total T3, total T4, and reverse T3, and those that assess for autoantibodies that can affect thyroid function: thyroid peroxidase antibody, thyroglobulin antibody, and TSH receptor antibodies. All antibody-based immunoassays are subject to potential interference. At its worst, immunoassay interference has been known to lead to unnecessary interventions, including chemotherapy and surgery. Although the prevalence of thyroid nodules is much lower in the pediatric population than in adults, these nodules are associated with a five times greater risk of malignancy.
