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

Abstract

Objective: The role of exercise testing in the assessment of GH deficiency (GHD) in adult patients is currently unclear. This study aimed at evaluating the diagnostic value of exercise-induced GH levels in the detection of severe GHD in adult patients. Methods: Fourteen patients confirmed to have severe GHD according to current guidelines and 20 healthy control individuals (CI) exercised for 120 min at 50-60% of their individual VO2 max . GH was measured before and every 30 min throughout exercise. The diagnostic value of predicting GHD was assessed by performing receiver operating characteristics (ROC) analysis for each time point of GH assessment. To optimise comparability within the study population a sub-analysis with ten individuals specifically matched for gender, age, body mass index and waist was performed. Results: Exercise-induced GH secretion was significantly lower in patients with GHD than in CI (P!0.001). Area under the ROC curve (AUC ROC ) was 0.954G0.033, 0.993G0.009, 0.989G0.012 and 0.992G0.009 for the overall population and 0.870G0.086, 0.980G0.024, 0.970G0.034 and 0.978G0.027 for the matched individuals at 30, 60, 90 and 120 min of exercise respectively. At 60 min of exercise a cut off GH value of 2.4 ng/ml translates into a sensitivity of 100% and a specificity of 95 and 90% in the diagnosis of GHD for the overall population and matched individuals respectively. Conclusion: GH assessment during a standardised aerobic exercise of moderate intensity is a reliable test with high diagnostic accuracy in predicting severe GHD in adult individuals. Based on the current findings exercise duration of 60 min appears to be sufficient for diagnostic purposes.

Peak oxygen uptake test in the assessment of growth hormone deficiency

“…While we have recently shown that a standardized aerobic exercise of moderate intensity but longer duration is a reliable test in predicting severe GHD in adult individuals (Zueger et al 2011), the present study provides evidence that an excellent accuracy can also be obtained using a shorter test protocol albeit with higher exercise intensity.…”

“…Although GHD may be regarded a comparably rare disease, its frequency may be considerably higher in specialized referral centers (Zueger et al 2011) and reliable tests for GHD are, therefore, important to identify individuals that may potentially benefit from GH replacement therapy. The insulin tolerance test is considered to be one of the gold standards in assessing the integrity of the GH axis.…”

“…We have recently shown that GH assessment during a 2-h standardized aerobic exercise of moderate intensity is a reliable test with high diagnostic accuracy in predicting severe growth-hormone deficiency (GHD) in adult individuals (Zueger et al 2011). As a consequence, exercise testing has been suggested to offer a safe and less invasive option compared with other diagnostic modalities (e.g., insulin tolerance testing) in the diagnosis of GHD in adult patients.…”

Regulation of fuel metabolism during exercise in hypopituitarism with growth hormone-deficiency (GHD)

“…In healthy subjects exercise induces a strong GH secretion [17]. In patients suffering from GHD such an exercise induced GH-response is lacking [31,32]. Since GH is known to have a strong lipolytic effect [23] we speculate that lipolysis may also be reduced during exercise in patients with GHD compared to healthy individuals.…”