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Pituitary function tests in Sheehan's syndome.

Fourteen patients with a typical history of Sheehan's syndrome underwent pituitary function tests with simultaneous injections of 100 micrograms LH-RH, 200 micrograms TRH and 0.05--0.1 units of soluble insulin per kg body weight. Serum prolactin levels remained unchanged in all of eleven subjects given TRH. GH levels did not rise after hypoglycaemia in five subjects. In contrast serum LH and FSH rose significantly in twelve out of fourteen subjects given LHRH and serum TSH rose significantly in five out of seven subjects given TRH. It is concluded that pituitary function is relatively preserved for LH and FSH but not for prolactin and GH in Sheehan's syndrome. It is further suggested that absence of a rise in prolactin following TRH stimulation may provide the most sensitive test of pituitary hypofunction in postpartum haemorrhage.

Adult↗

Specific effect of CV 205-502, a potent nonergot dopamine agonist, during a combined anterior pituitary function test.

CV 205-502, an octahydrobenzo[g]quinoline, is a dopamine agonist compound that is not an ergot or ergoline derivative. To investigate the site of action of CV 205-502, three groups of five men were given single daily doses of CV 205-502 (0.04, 0.06, or 0.08 mg/day, doses that suppress plasma PRL by 60-80% for 24 h) for 5 days; on day 6 a combined anterior pituitary function test using iv administration of four hypothalamic releasing hormones (TRH, 200 micrograms; GHRH, 100 micrograms; CRH, 100 micrograms; LHRH, 100 micrograms) was performed. One month later the challenge tests were repeated to obtain control values. The following hormones were measured by RIA in plasma: TSH, ACTH, cortisol, PRL, GH, LH, FSH, and testosterone. With the exception of plasma PRL levels, basal and releasing hormone-stimulated values were similar after CV 205-502 administration and after the 1-month washout period. Basal plasma PRL was lower after CV 205-502 administration, and the response to TRH was attenuated by all three doses of CV 205-502 (the mean percent inhibition values were 76%, 93%, and 94%, respectively). All three doses of CV 205-502 were well tolerated, and another group of men well tolerated 0.1 mg daily. The results confirm that CV 205-502 is a potent dopamine agonist, which directly inhibits lactotropic cells but has no effect on other pituitary cell types.

Adult↗

Pituitary function test and endocrine status in patient with cirrhosis of the liver before and after hepatic transplantation.

OBJECTIVE: Hormonal alterations caused by chronic liver disease are well described. In contrast, the reversibility of peripheral hormonal changes after orthotopic liver transplantation (OLT) has only partially been analyzed since the establishment of OLT as treatment of chronic hepatic failure. In addition it is not finally verified if chronic liver failure and especially hepatic encephalopathy also affect pituitary function. We therefore performed extensive endocrine studies including a global pituitary stimulation test before and after liver transplantation. METHODS: 22 patients with chronic alcoholic and non alcoholic liver failure were included in this prospective study. Basal hormone values (ACTH, cortisol, FSH, GH, IGF-I, LH, oestradiol, PRL, thyroid hormones and testosterone) were measured before and up to 5 years after OLT. Furthermore all patients underwent pituitary function tests with application of GRF, TRH, GnRH, and CRF before, 3 weeks and 3 months after OLT. RESULTS: Estradiol, LH and FSH increased significantly in postmenopausal and only slightly in premenopausal female patients after OLT. Total testosterone revealed no marked changes and was normal before and up to five years after OLT in male patients. After stimulation with GnRH the LH response in females and the FSH response in males was significantly higher three months after OLT than pretransplant. LH response in males and FSH response in females was only slightly higher after OLT. Peripheral IGF-I was low and growth hormone was elevated in all patients prior OLT. Growth hormone declined significantly three months afterwards. The response to GRF was highest prior OLT and decreased afterwards. Prolactin values were normal prior and post OLT. After stimulation with TRH prolactin values in male patients were significantly higher before OLT than afterwards. CONCLUSION: In the observed relatively small number of patients gross pituitary function in chronic liver failure remained intact, whereas slight alterations in several axis were found. These pituitary alterations are presumably only partially caused by feedback mechanisms. Both a normalisation of peripheral endocrine parameters and pituitary function were achieved by OLT despite significant alterations pretransplant.

Adrenocorticotropic Hormone↗

A retrospective audit of the combined pituitary function test, using the insulin stress test, TRH and GnRH in a district laboratory.

OBJECTIVE: To assess the value of the combined insulin stress test (IST), thyrotrophin-releasing hormone (TRH) and gonadotrophin hormone-releasing hormone (GnRH) tests. DESIGN: A retrospective audit of 232 such tests performed between 1980 and 1989 inclusive. PATIENTS: One hundred and ninety-seven patients with known or suspected pituitary disease. MEASUREMENTS: IST, TRH and GnRH responses were retrieved from laboratory records. Case notes were surveyed for clinical data and additional results. RESULTS: A basal serum cortisol level of less than 100 nmol/l (or less than 200 nmol/l in patients who had recently received glucocorticoid replacement therapy) accurately predicted a subnormal response to hypoglycaemia. All patients with a basal cortisol level of greater than 400 nmol/l, except those who had recently received steroids, showed a normal cortisol response. In retrospect, by consideration of such basal values, 55% of ISTs could have been avoided if the only aim was to assess cortisol reserve. A deficient growth hormone (GH) response to hypoglycaemia was, however, common in patients with a normal cortisol response. Two-thirds of patients with GH deficiency would have been missed if an IST had been avoided on the basis either of basal cortisol levels alone, or of cortisol responses to an alternative test which did not test GH reserve. There was poor agreement between the pituitary response to TRH and GnRH and basal levels of thyroxine and gonadotrophins respectively, suggesting that these releasing hormone tests are misleading. CONCLUSIONS: The IST provides information regarding pituitary function not provided by other tests of the hypothalamic-pituitary-adrenal axis, so that the choice between the IST and alternative tests must depend on a critical assessment of what information is required. Routine TRH and GnRH testing appears to yield little information of practical clinical value.

Gonadotropin-Releasing Hormone↗

[Evaluation of dynamic pituitary function testing in patients with hyperprolactinemia on diagnosis of pituitary prolactin-secreting adenoma (author's transl)].

Thirty hyperprolactinemic women were divided into four group according to radiological and computed tomographic findings of sella turcica as follows; sulpiride-induced (N = 7), functional (N = 6), microadenoma (N = 9) and macroadenoma (N = 8). It was measured the serum basal level of pituitary LH, FSH, PRL, TSH and GH, and the responsiveness to LH-RH, TRH, insulin administration, respectively. These values were compared to that during bromocriptine treatment (5mg/day, 2 weeks). Before and during treatment with bromocriptine, there were not significant changes of basal level of LH, FSH and TSH, and also the responsiveness to LH-RH administration in four group. In pretreatment period, PRL responsiveness to TRH was good in sulpiride-induced and functional groups, but decreased in microadenoma and macroadenoma groups. During bromocriptine treatment period, basal PRL level was significantly suppressed in three groups except sulpiride-induced group, and PRL responsiveness to TRH was good in three groups except macroadenoma group. These findings ae concluded as follows: 1) Mechanism of the disturbance of ovulation in hyperprolactinemia does not closely related to pituitary gonadotroph dysfunction. 2) Decreased PRL responsiveness to TRH (maximal fold increase: under 40%) is of diagnostic value of pituitary adenomas. 3) Difference of PRL responsiveness to TRH during treatment with bromocriptine is distinguishing the microadenoma from macroadenoma.

Adenoma↗

Assessment of a combined anterior pituitary function test in beagle dogs: rapid sequential intravenous administration of four hypothalamic releasing hormones.

A combined anterior pituitary (CAP) function test was assessed in eight healthy male beagle dogs. The CAP test consisted of sequential 30-second intravenous administrations of four hypothalamic releasing hormones in the following order and doses: 1 microgram of corticotropin-releasing hormone (CRH)/kg, 1 microgram of growth hormone-releasing hormone (GHRH)/kg, 10 micrograms of gonadotropin-releasing hormone (GnRH)/kg, and 10 micrograms of thyrotropin-releasing hormone (TRH)/kg. Plasma samples were assayed for adrenocorticotropin, cortisol, GH, luteinizing hormone (LH), and prolactin (PRL) at multiple times for 120 min after injection. Each releasing hormone was also administered separately in the same dose to the same eight dogs in order to investigate any interactions between the releasing hormones in the combined function test. Compared with separate administration, the combined administration of these four hypothalamic releasing hormones caused no apparent inhibition or synergism with respect to the responses to CRH, GHRH, and TRH. The combined administration of these four hypothalamic releasing hormones caused a 50% attenuation in LH response compared with the LH response to single GnRH administration. The side effects of the combined test were confined to restlessness and nausea in three dogs, which disappeared within minutes after the administration of the releasing hormones. It is concluded that with the rapid sequential administration of four hypothalamic releasing hormones (CRH, GHRH, GnRH, and TRH), the adenohypophyseal responses are similar to those occurring with the single administration of these secretagogues, with the exception of the LH response, which is lower in the CAP test than after single GnRH administration.

Adrenocorticotropic Hormone↗

Pituitary function tests in the elderly: are hypothalamic releasing factors the investigation of choice?

The use of the new hypothalamic releasing factors corticotrophin releasing factor (CRF) and growth hormone releasing factor (GHRH) has been proposed as a potential replacement for the insulin stress test in the investigation of pituitary function. The response to the injection of 100 micrograms of each compound was studied in nine elderly in-patient subjects. In response to GHRH, only four subjects demonstrated a rise in growth hormone; in response to CRF, only one subject showed a rise in cortisol. In the patients studied the combined GHRH and CRF test did not cause any cortisol or GH response in the majority.

Aged↗