=====Glucagon stimulation test=====
Recent studies suggest using lower [[GH]] cut-points for the [[glucagon]] stimulation test (GST) in diagnosing adult GH deficiency (GHD), especially in obese patients. There are limited data on evaluating GH and hypothalamic-pituitary-adrenal (HPA) axes using weight-based dosing for the GST.

To define GH and cortisol cut-points to diagnose adult GHD and secondary [[adrenal insufficiency]] (SAI) using the GST, and to compare fixed-dose (FD: 1 or 1.5 mg in patients >90 kg) with weight-based dosing (WB: 0.03 mg/kg). Response to the insulin tolerance test (ITT) was considered the gold standard, using GH and cortisol cut-points of ≥3 ng/ml and ≥18 µg/dL, respectively.

28 Patients with hypothalamic-pituitary disease and 1-2 (n = 14) or ≥3 (n = 14) pituitary hormone deficiencies, and 14 control subjects matched for age, sex, estrogen status and body mass index (BMI) underwent the ITT, FD- and WB-GST in random order.

Age, sex ratio and BMI were comparable between the three groups. The best GH cut-point for diagnosis of GHD was 1.0 (92 % sensitivity, 100 % specificity) and 2.0 ng/mL (96 % sensitivity and 100 % specificity) for FD- and WB-GST, respectively. Age negatively correlated with peak GH during FD-GST (r = -0.32, P = 0.04), but not WB-GST. The best cortisol cut-point for diagnosis of SAI was 8.8 µg/dL (92 % sensitivity, 100 % specificity) and 11.2 µg/dL (92 % sensitivity and 100 % specificity) for FD-GST and WB-GST, respectively. Nausea was the most common side effect, and one patient had a seizure during the FD-GST.

The GST correctly classified GHD using GH cut-points of 1 ng/ml for FD-GST and 2 ng/ml for WB-GST, hence using 3 ng/ml as the GH cut-point will misclassify some GH-sufficient adults. The GST may also be an acceptable alternative to the ITT for evaluating the HPA axis utilizing cortisol cut-points of 9 µg/dL for FD-GST and 11 µg/dL for WB-GST
((Hamrahian AH, Yuen KC, Gordon MB, Pulaski-Liebert KJ, Bena J, Biller BM.
Revised GH and cortisol cut-points for the glucagon stimulation test in the
evaluation of GH and hypothalamic-pituitary-adrenal axes in adults: results from 
a prospective randomized multicenter study. Pituitary. 2016 Feb 20. [Epub ahead
of print] PubMed PMID: 26897383.
)).
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Until a potent, safe and reliable test becomes available, the GST should remain as the alternative to the [[insulin tolerance test]] (ITT)  in the United States. In order to reduce over-diagnosing adult GHD in overweight/obese patients with the GST, Yuen 
et al propose utilizing a lower GH cut-point of 1 μg/L in these subjects. However, this lower GH cut-point still needs further evaluation for diagnostic accuracy in larger patient populations with varying BMIs and degrees of glucose tolerance
((Yuen KC, Tritos NA, Samson SL, Hoffman AR, Katznelson L. AMERICAN ASSOCIATION 
OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE
CLINICAL REVIEW: UPDATE ON GROWTH HORMONE STIMULATION TESTING AND PROPOSED
REVISED CUT-POINT FOR THE GLUCAGON STIMULATION TEST IN THE DIAGNOSIS OF ADULT
GROWTH HORMONE DEFICIENCY. Endocr Pract. 2016 Jul 13. [Epub ahead of print]
PubMed PMID: 27409821.
)).