Management of primary hypothyroidism

Primary hypothyroidism is a common condition requiring lifelong treatment and monitoring. The type and amount of thyroid hormone replacement, selection of laboratory tests, and timing of office visits are all important for optimizing patient well-being and reducing the costs of medical care. The aim of treatment is to bring the patient to the euthyroid state. Currently this is defined as a normal serum concentration of TSH by recently developed sensitive and specific immunometric assays, and is accomplished by titrating the dose of levothyroxine and changing it not more often than at 4- to 6-week intervals. As an indicator of euthyroidism, the sensitive TSH assay has advantages over tests of serum T4, FT4I, T3, FT4, and TSH by RIA because it is independent of TBG changes that result from pregnancy, birth-control pills, and estrogen replacement, is not spuriously elevated by the levothyroxine treatment itself, and is the only test that detects both subclinical hypothyroidism and subclinical hyperthyroidism. Additional serum tests are not usually necessary but have advantages under special circumstances. Once the optimal replacement dose is determined, monitoring can be done yearly or even bi-yearly, depending on the adequacy of patient education and patient compliance.