There is high risk for H in TBI and SAH patients. Early diagnosis of PH is always confirmed in the long term. Pituitary function in brain-injured patients may improve over time but, although rarely, may also worsen. Thus, brain-injured patients must undergo neuroendocrine follow-up over time.

Objective: The diagnosis of growth hormone (GH) deficiency (GHD) in adults is based on a reduced peak GH response to provocative tests, such as the insulin tolerance test (ITT) and the GH-releasing hormone-arginine (GHRH-ARG) test. However, the cut-off limits of peak GH response in lean subjects are not reliable in obese patients; this is noteworthy since adult GHD is often associated with obesity. Aim of this study was to evaluate the diagnostic cut-off limits of peak GH response to the GHRH-ARG test in overweight and obese as well as in lean population. Design and methods: The GH responses to the GHRH-ARG test were studied in 322 patients with organic hypothalamic-pituitary disease and in 318 control subjects. Patients were subdivided into two groups on the basis of the number of pituitary hormone deficits, except for GH deficiency: (a) patients with total pituitary hormone deficit (TPHD) and (b) patients without or with no more than two pituitary hormone deficits (PHD). Both patients and control subjects were divided into three subgroups according to body mass index (BMI): lean (BMI , 25 kg/m 2 ), overweight (BMI $ 25 and , 30 kg/m 2 ) and obese (BMI $30 kg/m 2 ). TPHD patients were assumed to be GH deficient, whereas PHD patients may include subjects with either normal or impaired GH secretion. The statistical analysis was carried out by the Receiver-Operating Characteristic curve analysis (Medcalc 7.2). The diagnostic cut-off points were calculated for lean, overweight and obese subjects to provide optimal separation of GH-deficient patients and control subjects according to two criteria: (1) a balance between high sensitivity and high specificity; (2) to provide the highest pair of sensitivity/specificity values for GH deficiency. Results: In the lean population the best pair of values, with highest sensitivity as 98.7% and highest specificity as 83.7%, was found using a peak GH cut-off point of 11.5 mg/l. In the overweight population the best pair of values, 96.7 and 75.5%, respectively, was found using a peak GH cut-off point of 8.0 mg/l. In the obese population the best pair of values, 93.5 and 78.3%, respectively, was found using a peak GH cut-off point of 4.2 mg/l. Applying the above mentioned cut-off points, among PHD patients we found that 80 subjects (72%) were GHD whereas 31 (28%) had normal GH secretion. Conclusions: In conclusion the GHRH-ARG test is a reliable tool for the diagnosis of adult GH deficiency in lean, overweight and obese patients, provided that specific BMI-related cut-off limits are assumed.European Journal of Endocrinology 153 257-264

Ghrelin stimulates appetite and plays a role in the neuroendocrine response to energy balance variations. Ghrelin levels are inversely associated with body mass index (BMI), increased by fasting and decreased by food intake, glucose load, insulin, and somatostatin. Ghrelin levels are reduced in obesity, a condition of hyperinsulinism, reduced GH secretion, and hypothalamus-pituitary-adrenal axis hyperactivity. We studied the endocrine and metabolic response to acute ghrelin administration (1.0 microg/kg i.v.) in nine obese women [OB; BMI (mean +/- SD) 36.3 +/- 2.3 kg/m(2)] and seven normal women (NW; BMI 20.3 +/- 1.7 kg/m(2)). Basal ghrelin levels in NW were higher than in OB (P < 0.05). In NW, ghrelin increased (P < 0.05) GH, prolactin (PRL), ACTH, cortisol, and glucose levels but did not modify insulin. In OB, ghrelin increased (P < 0.01) GH, PRL, ACTH, and cortisol levels. The GH response to ghrelin in OB was 55% lower (P < 0.02) than in NW, whereas the PRL, ACTH, and cortisol responses were similar. In OB, ghrelin increased glucose and reduced insulin (P < 0.05). Thus, obesity shows remarkable reduction of the somatotroph responsiveness to ghrelin, suggesting that ghrelin hyposecretion unlikely explains the impairment of somatotroph function in obesity. On the other hand, in obesity ghrelin shows preserved influence on PRL, ACTH, and insulin secretion as well as in glucose levels.

Total IGF-I levels are often normal even in patients with total anterior hypopituitarism but this does not rule out severe GHD that therefore ought to be verified by provocative testing of GH secretion. However, despite the low diagnostic sensitivity of this parameter, very low levels of total IGF-I can be considered definitive evidence of severe GHD in a remarkable percentage of total anterior hypopituitary patients who could therefore skip provocative testing of GH secretion.

Objective: To define the appropriate diagnostic cut-off limits for the GH response to GHRHCarginine (ARG) test and IGF-I levels, using receiver operating characteristics (ROC) curve analysis, in late adolescents and young adults. Design and methods: We studied 152 patients with childhood-onset organic hypothalamic-pituitary disease (85 males, age (meanGS.E.M.): 19.2G0.2 years) and 201 normal adolescents as controls (96 males, age: 20.7G0.2 years). Patients were divided into three subgroups on the basis of the number of the other pituitary hormone deficits, excluding GH deficiency (GHD): subgroup A consisted of 35 panhypopituitary patients (17 males, age: 21.2G0.4 years), subgroup B consisted of 18 patients with only one or with no more than two pituitary hormone deficits (7 males, age: 20.2G0.9 years); and subgroup C consisted of 99 patients without any known hormonal pituitary deficits (60 males, age: 18.2G0.2 years). Both patients and controls were lean (body mass index, BMI!25 kg/m 2 ). Patients in subgroup A were assumed to be GHD, whereas in patients belonging to subgroups B and C the presence of GHD had to be verified. Results: For the GHRHCARG test, the best pair of highest sensitivity (Se; 100%) and specificity (Sp; 97%) was found choosing a peak GH of 19.0 mg/l. For IGF-I levels, the best pair of highest Se (96.6%) and Sp (74.6%) was found using a cut-off point of 160 mg/l (SDS: K1.3). Assuming 19.0 mg/l to be the cut-off point established for GHRHCARG test, 72.2% of patients in subgroup B and 39.4% in subgroup C were defined as GHD. In patients belonging to group B and C and with a peak GH response !19 mg/l to the test, IGF-I levels were lower than 160 mg/l (or less than 1.3 SDS) in 68.7 and 41.6% of patients respectively predicting severe GHD in 85.7% of panhypopituitary patients (subgroup A). Conclusions: In late adolescent and early adulthood patients, a GH cut-off limit using the GHRHCARG test lower than 19.0 mg/l is able to discriminate patients with a suspicion of GHD and does not vary from infancy to early adulthood. European Journal of Endocrinology 157 701-708