The diagnosis of growth hormone deficiency (GHD) by stimulation tests relies on measurement of growth hormone (GH) secretion, but there are several challenges to associated with the GH secretion test.
Furthermore, the GH secretion test may be influenced by factors such obesity, undernutrition, sex, age, puberty, and presence of chronic diseases. It also has potential adverse reactions and may sometimes result in hospitalization. Therefore, a predictive biomarker for GHD is desired to avoid unnecessary GH secretion test.
Previous research has suggested that insulin-like growth factor-1 (IGF-1), a small polypeptide hormone secreted by the liver when stimulated by GH, may be a potential biomarker for GHD, which was the focus of a recent study published in Scientific Reports by Hideyuki Iwayama and colleagues.
The study authors evaluated the diagnostic accuracy of IGF-1 for screening GHD in a group of 298 consecutive children who had short stature or decreased height velocity. Children with congenital abnormalities were excluded from the study.
Investigators measured IGF-1 levels and performed GH secretion testing using clonidine, arginine, and, in cases with different results of the two tests, L-dopa. GHD was defined as peak GH ≤ 6.0 ng/mL in the two tests.
Overall, 60 patients were found to have GHD, and 238 patients did not have GHD. The researchers observed that mean IGF-1 standard deviation was not significantly different between the GHD and non-GHD groups (p=0.23). Receiver operating characteristic curve analysis demonstrated the best diagnostic accuracy at an IGF-1 cutoff of −1.493 SD, with 0.685 sensitivity, 0.417 specificity, 0.25 positive and 0.823 negative predictive values, and 0.517 area under the curve.
Correlation analysis revealed that no specific patient characteristic increased the diagnostic power of IGF-1, the authors reported. Overall, “IGF-1 level had poor diagnostic accuracy as a screening test for GHD,” they concluded. “Therefore, IGF-1 should not be used alone for GHD screening. A predictive biomarker for GHD should be developed in the future.”