Clinical hypothyroidism in the elderly--a preventable disorder?

Among 27 ambulatory aged patients receiving thyroxine therapy for hypothyroidism, 4 had the "failing thyroid syndrome" (FTS) and 23 had frank clinical hypothyroidism. Patients with FTS are asymptomatic and the subnormal thyroid function is recognized only by a high level of serum thyrotropin (TSH) with a normal level of thyroid hormone (thyroxine or triiodothyronine). They require a smaller dosage of thyroid hormone for replacement initially. Identification of these cases through routine blood analyses for TSH in patients at risk (those with a history of Graves' disease or Hashimoto's thyroiditis) may permit early treatment of incipient hypothyroidism and the prevention of clinical hypothyroidism. Since there is a reduction in the thyroxine dosage required for complete replacement with age, the expected final replacement dosage when the thyroid fails completely is less than that reported for younger adults. This is true for patients with FTS, for patients with newly diagnosed clinical hypothyroidism, and for patients with long-established hypothyroidism receiving replacement therapy. The thyroid replacement dosage should be adjusted both for age and for body weight to avoid overdosage and thyroid toxicity, to which the elderly are particularly sensitive.