Fast, short-term response to TRH stimulation in geriatric patients and its clinical importance

In 52 geriatric patients, average age of 74 years (range from 65 to 89) suffering from generalised arteriosclerotic disease and hospitalized at the Clinical Institute for Geriatrics, we found normal thyroid gland function, in basal condition. Our data showed that 19.42% of the patients had low triiodothyronine (T(3)) concentrations. Basal serum T(3) level was higher (P < 0.01) in males (1.88 +/- 0.44 nmol/l) in comparison to values in females (1.75 +/- 0.28). Serum thyroxine (T(4)) level was lower in males (P < 0.01), but the concentrations of thyreo stimulating hormone (TSH) was lower in females. The value of thyroid reserve in elderly people, estimated by measuring T(3) and T(4) incretion shortly after thyreotropin releasing hormone (TRH) was done, is sufficient to maintain cuthyroid function, although it is, as a whole, significantly lower if compared with T(4) and T(3) response after TRH tests in middle-aged subjects (n = 26), acting as a control group (P < 0.001). Thyroxine excretion from follicular cells in elderly female patients was faster and amplitude was higher, up to the maximal possible level 93 nmol/l (+/- SD) in 25 min after an injection of TRH. In elderly male patients the maximum of T(4) excretion was 78 nmol/l (P < 0.01) at 60 min.