Altered laboratory thyroid parameters indicating hyperthyroidism in elderly subjects.
The most common laboratory alterations of thyroid function indicating hyperthyroidism were evaluated in a series of 3015 subjects over 65 years of age by determining total T3, total T4 and TSH. Ultrasound and scintigraphy of the thyroid were performed where necessary. Our results showed a high prevalence of laboratory alterations hyperthyroidism type of around 8.09%, whereas the real prevalence (both clinical and laboratory) is 2.00% with a female/male ratio of 2.00. The most frequent hyperfunctioning thyreopaty is thyroidal adenoma (50%), followed by toxic multinodular goiter (33%) and Basedow's disease (17%). The most common clinical signs of hyperthyroidism involve the neuromuscular system and are often present in the so called 'euthyroid' elderly subject. We conclude that it is very difficult to diagnose hyperthyroidism in the elderly on clinical and laboratory grounds. The most significative laboratory thyroid parameter indicating hyperthyroidism seems to be TSH values below 0.2 IU/ml determined using the ultrasensitive IRMA method.