Hyperthyroidism and the impalpable thyroid gland.

A retrospective analysis of 594 unselected cases of hyperthyroidism from one district was made to determine whether the thyroid gland had been palpable on presentation. The thyroid had been diffusely palpable in 374 patients (63%), nodular in 110 (19%) and impalpable in 96 (16%); there was no clinical record in 14 (2%) cases. Under 40 years of age a diffuse gland was usual, being present in 86% of cases. The proportion of nodular and impalpable glands both increased progressively with age comprising 30% and 48% respectively in patients older than 70 years. Grave's ophthalmopathy was present in 13% of hyperthyroid patients with diffuse glands, in 12% of those with impalpable glands, but in only 1.5% of those with nodular thyroids. Thyroid autoantibodies were found with a similar frequency in all three groups. There was a very good correspondence between clinical assessment of shape and nodularity of thyroid and the results of isotope scanning; the majority of patients with impalpable glands (86%) had a diffuse uptake of isotope. In the elderly hyperthyroid patient an impalpable thyroid gland is common and is not a factor to weight against the diagnosis.