Investigation of Thyroid Dysfunction

Investigation of Thyroid Dysfunction

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Thyroid stimulating hormone (TSH) is the initial test for the diagnosis of primary hyperthyroidism and hypothyroidism. The measurement of TSH levels is the most sensitive and specific test for thyroid dysfunction. The new generation of sensitive immunoradiometric TSH assays can reliably detect a concentration as low as 0.01 mU/L. Reference values range between 0.15 mU/L and 6 mU/L, but some variations are possible in different laboratories. Sensitivity and specificity of TSH is in excess of 90 percent in detecting thyroid disease (Caldwell, 1985).