The Diagnosis and Management of Hypothyroidism

Bhuvana Guha, MD, Guha Krishnaswamy, MD, And Alan Peiris, MD, PhD, MRCP

Disclosures

South Med J. 2002;95(5):475-480. 

In This Article

Thyroxine Replacement in Special Situations

The presence of a normal free-T4 level with elevation of TSH values is found in subclinical hypothyroidism. The point at which therapy should be initiated has been controversial. The work-up for this condition should include antithyroid antibodies tests and fasting lipid levels. Patients with positive tests for thyroid antibodies should be treated. Patients whose tests for thyroid antibodies are negative, but whose TSH values are >10 mg/mL, should also be treated. Patients with goiter, elevated lipid levels, pregnancy, ovulatory dysfunction/infertility, or impaired cardiac contractility may also be treated. It is difficult to assess the relationship of mild, subclinical hypothyroidism and general health concerns in some patients, and some physicians will initiate therapy while others advocate follow-up with annual laboratory testing.[10]

The thyroxine dose needs to be increased during pregnancy.[20] A study by Haddow et al[21] indicated that maternal thyroid deficiency during pregnancy could impair neuropsychological development in children. Thyroxine replacement in elderly and/or cardiac patients needs to be initiated at a low dose (eg, 12.5-25 mg daily), with a gradual increase (eg, 12.5-25 µg every 3-4 weeks) and monitoring of thyroid function and clinical status. Patients who need elective surgery can be rescheduled after thyroid function has normalized.[22] Surgery should proceed for patients who need surgery immediately, and they should be given simultaneous replacement therapy with thyroxine. The route of administration and the dose will be influenced by age and concomitant health factors of the patient, such as the presence of cardiac disease. Hypothyroidism may also be associated with postoperative complications.[22]

Thyroid function tests are routinely checked when patients are admitted to the psychiatric ward. Noncompliance with daily thyroxine replacement is often seen in psychiatric patients. The administration of doses once or twice weekly is effective and without side effects; moreover, this method of administration may enhance compliance and decrease the need for hospitalization.[23] Psychiatrists have sometimes used both T4 and T3 replacement in pharmacologic doses to treat refractory depression and bipolar disease. Further studies are needed to confirm: a) the efficacy of these regimens; b) any synergy between traditional antidepressants and thyroxine therapy; and c) lack of adverse effects, including osteopenia. Pending these studies, the role of adjunctive thyroid-hormone therapy for refractory depression and bipolar disease remains a controversial option. In depressed patients receiving thyroxine treatment for hypothyroidism, it may be reasonable to consider a TSH-level goal closer to the lower limit of the normal range, although this issue also needs to be addressed by additional studies.

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