Do acute diseases transiently impair anterior pituitary function in patients over the age of 75? A longitudinal study of the TRH test and basal gonadotrophin levels

Abstract

Several studies have shown that anterior pituitary function is affected by the ageing process. Little is known, however, about the effect acute diseases have on the anterior pituitary. Should they be associated with a disturbance of anterior pituitary hormone production, they might make anterior pituitary function tests difficult to interpret when they are most needed. To test this hypothesis, we studied the thyrotrophin (TSH) releasing hormone (TRH) test and basal plasma gonadotrophins, taken as indicators of anterior pituitary function and reserve, in 74 consecutive patients (49 women) mean age 82 ± 5.1 suffering from acute diseases soon after admission to hospital. A total of 44 (30 women) were followed up and retested after 3 disease-free months following recovery and discharge home. Seventy-one age- and sex-matched healthy controls (47 women), mean age 82 ± 5.0 living in the community were also studied. The mean peak TSH increment after TRH (mean Amax TSH) increased from 5.7 soon after admission, to 7.7 U/l at follow-up (P = 0.01). The mean plasma LH increased from 25 to 35 U/l in women (P = 0.0004) and from 9.7 to 14 U/l in men (P = 0.03). The mean plasma FSH increased from 21 to 25 U/l in women (P = 0.04) and from 7.5 to 9.4 U/I in men (P = 0.01). Controls had greater TSH responses to TRH and higher plasma gonadotrophins levels when compared with acute patients (LH women P = 0.17, for all other tests P<0.05). We conclude that a transient reduction of anterior pituitary function is a common occurrence in patients over the age of 75 suffering from acute diseases. This has diagnostic relevance and therapeutic implications.