It can be readily appreciated from the preceding discussion that many endocrine and non-endocrine tests are available for the evaluation of patients with suspected hypothalamic-
pituitary disease. The endocrine evaluation of these subjects should be tailored according to the type and extent of pathology suspected (see Tables 2 and 3). For patients with
pituitary adenomas and clinical features of
hyperpituitarism, such as
hyperprolactinaemia,
Cushing's disease or
acromegaly, the initial tests should be directed at the
hormone whose excess is suspected. For example, a
glucose suppression test for
acromegaly or
dexamethasone suppression test for
Cushing's disease should be performed early in the evaluation. The possibility of deficiencies of the other
pituitary hormones should then be addressed in patients with secretory tumours, but initially in those with apparent non-functioning
adenomas. In patients with large macroadenomas pituitary
hormone deficiencies are almost invariable with GH and FSH/LH being the most commonly affected, followed by TSH and
ACTH in that order (Snyder et al, 1979a; Valenta et al, 1982). Basal thyroid function tests, serum
oestradiol or
testosterone, and basal gonodotrophins should be routinely obtained in patients with macroadenomas. Additionally, the integrity of the pituitary-adrenal axis should be determined and an overnight water deprivation test for assessment of neurohypophyseal function is also recommended. GH stimulation testing is valuable as a test of pituitary function in patients with suspected pituitary tumours since GH reserve is lost very early in the development of
hypopituitarism. Evaluation of the pituitary-thyroid axis with TRH or the pituitary gonadal axis with
LHRH generally provides limited additional information of diagnostic value in individual patients with macroadenomas. However, the 'paradoxical' responses to TRH and
LHRH may be useful as a
biological marker following
therapy in patients with GH- or
ACTH-secreting tumours. In patients with microadenomas, pituitary
hormone deficiencies are uncommon (Valenta et al, 1982). Despite this observation, it may be beneficial to determine basal thyroid levels, gonadotrophin levels, serum
testosterone or
oestradiol levels, and the response to an overnight
metyrapone test in such patients to provide a baseline for future care.(ABSTRACT TRUNCATED AT 400 WORDS)