. Author manuscript; available in PMC: 2018 May 17.

Published in final edited form as: Endocrinol Metab Clin North Am. 2017 Jun 8;46(3):631–648. doi: 10.1016/j.ecl.2017.04.002

Table 1.

Clinical uses of biochemical tests for thyroid disorders

Biochemical Test	Clinical Uses
TSH	• Primary screening test for thyroid dysfunction • Evaluation of thyroid hormone replacement therapy in patients with primary hypothyroidism • Evaluation of suppressive therapy in patients with follicular cell-derived thyroid cancer
T4	• Detection of thyroid dysfunction in conjunction with TSH • Evaluation of thyroid hormone replacement therapy in patients with secondary hypothyroidism (free T4) • Evaluation of thyroid dysfunction in pregnancy (total T4)
T3	• Detection of hyperthyroidism • No usefulness in the management of hypothyroidism • May be useful in diagnosis of nonthyroidal illness
Thyroid autoantibodies	• Positive in autoimmune thyroid disease • TPOAb – evaluation of patients with subclinical hypothyroidism and women with recurrent miscarriages • TRAb – diagnosis of Graves’ disease; help to predict which Graves’ patients can be weaned from antithyroid medications
Thyroglobulin	• Evaluation of effectiveness of treatment for differentiated thyroid cancer and monitoring for residual or recurrent disease • Diagnosis of thyrotoxicosis factitia
Calcitonin	• To diagnose medullary thyroid cancer and monitor for recurrence, progression, and response to treatment

Abbreviations: T3, triiodothyronine; T4, thyroxine; TPOAb, antibodies to thyroid peroxidase; TRAb, antibodies directed against the thyroid-stimulating hormone receptor; TSH, thyroid-stimulating hormone.