The cut-off limits of the GH response to GH-releasing hormone-arginine test related to body mass index

Abstract

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

The visceral adiposity index is associated with insulin sensitivity and IGF-I levels in adults with growth hormone deficiency

“…Blood samples were taken every 30 min from 0 up to 90 min. The highest GH levels measured from time 30 to 90 min during the test were taken for analysis as peak GH and the diagnosis of GHD was made taking into account the BMI of patients [19]. The mean GH peak was 4.05 ± 1.45 µg/l in the group of 11 patients with BMI < 25 Kg/m 2 ; 2.10 ± 1.97 µg/l in the group of 23 patients with BMI ≥ 25 and <30 Kg/m 2 ; 1.95 ± 1.87 µg/l in the group of 18 patients with BMI ≥ 30 Kg/m 2 .…”

Exercise-induced GH secretion in the assessment of GH deficiency in adult individuals

“…The study population encompassed 14 patients with severe GHD and 20 control individuals (CI). Severe GHD was defined according to the current guidelines either based on an increase of GH to !5.1 ng/ml during an insulin tolerance test (ITT) with a nadir plasma glucose of !2.2 mmol/l and hypoglycaemic symptoms, or an insufficient GH releasing hormone (GHRH)/arginine test with body mass index (BMI)-dependent cut offs (11.5, 8.0 and 4.2 ng/ml for BMI !25, 25-30 and O30 kg/m 2 respectively), or insufficiency of at least three pituitary axes in addition to a low value for insulin-like growth factor 1 (IGF1) (11)(12)(13). Owing to a potential interference of oral oestrogens with IGF1 levels the diagnosis of GHD in female patients was based on stimulation testing, exclusively.…”

“…The diagnostic value in predicting GHD was calculated for each time point of GH assessment during exercise by performing receiver operating characteristics (ROC) analysis. In a ROC analysis, the diagnostic test under investigation (for the present analysis: exercise-induced GH concentrations) is compared with an accepted gold standard (for the present analysis: GHD assessed according to guidelines (11)(12)(13)). First, ROC analysis was performed including all GHD patients and all CI.…”

Prevalence of Pituitary Hormone Dysfunction, Metabolic Syndrome, and Impaired Quality of Life in Retired Professional Football Players: A Prospective Study

“…31,32 Because of this known inverse relationship with BMI and peak GH after stimulation testing with glucagon, GHRH/arginine, and insulin tolerance testing, GHD was defined at 3 cut points, adjusted for BMI using a normal non-head-injured control cohort referred to the Dynamic Endocrine Testing Unit at the Oregon Health & Science University (Portland, OR) for assessment of possible GHD with low normal to low serum IGF-1 levels. 27,[33][34][35][36] From 119 men tested, individuals were excluded if they had a previous history of pituitary or hypothalamic tumor, other hypothalamic or pituitary disorder, pituitary surgery or irradiation, or TBI. Thirty individuals from these 119 men met the criteria and made up the control group.…”