Thyroid Function Tests

Thyroid function tests are used to identify hypothyroidism or hyperthyroidism, and suggest their cause. This section outlines an approach to the interpretation of TFTs.

Thyroid Function

Thyroid Antibodies

Anti-Thyroglobulin Antibodies

Present in Hashimoto's, though rarely required for diagnosis
Anti-TPO Antibodies

Present in Hashimoto's, though rarely required for diagnosis
Anti-TSH Receptor Antibodies

Pathognomonic of Grave's, though not always required for diagnosis

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Thyroid Function

Thyroid Antibodies

Grounds D, Richmond V. Managing subclinical hypothyroidism. Australian Prescriber. 1999;22(6).

Halsall DJ, English E, Chatterjee VK. Interference from heterophilic antibodies in TSH assays. Annals of clinical biochemistry. 2009 Jul;46(4):345-6.

Kasagi K, Kousaka T, Higuchi K, Iida Y, Misaki T, Alam MS, Miyamoto S, Yamabe H, Konishi J. Clinical significance of measurements of antithyroid antibodies in the diagnosis of Hashimoto's thyroiditis: comparison with histological findings. Thyroid. 1996 Oct;6(5):445-50.

Koulouri O, Moran C, Halsall D, Chatterjee K, Gurnell M. Pitfalls in the measurement and interpretation of thyroid function tests. Best practice & research Clinical endocrinology & metabolism. 2013 Dec 1;27(6):745-62. Mortimer RH. Thyroid function tests. Australian Prescriber. 2011 Feb 1;34(1):12-5. Mullur R, Liu YY, Brent GA. Thyroid hormone regulation of metabolism. Physiological reviews. 2014 Apr;94(2):355-82.

Thyroid Function Tests

Suppressed TSH with Elevated T4

Suppressed TSH with Normal T4

Suppressed / Normal TSH with Reduced T4

Elevated TSH with Reduced T4

Elevated TSH with Normal T4

Normal / Elevated TSH with Elevated T4