Indications, limitations and pitfalls in the determination of human growth hormone, IGF-I and their binding proteins.
Deviations from normal growth are a major part of Pediatric Endocrinology. The principal post-natal growth promoting hormones are pituitary growth hormone (GH) and insulin-like growth factor-I (IGF-I). The GH-IGF-I axis has many links and portals, the secrets of which have been disclosed in recent years by scientific advances (genetic and biochemical technologies). In this article, we describe the players in the GH axis, the auxological indications for performing GH evaluation tests, enumerate the most frequently used tests and discuss the laboratory tests which help to define the pathological entities along the GH axis. Emphasis is put on the limitations of methods used, lack of standards, norms and the possible errors in diagnosis and treatment indications that may evolve. As both hGH and IGF-I immunoassay measurements represent cornerstones in the diagnosis and monitoring of the different etiological entities presenting with short stature, clinicians must have an insight into the variability and limitations of these analytical techniques. Interpretation of biochemical results without proper reference data and without knowledge of the assay-inherent characteristics inevitably leads to misdiagnosis, unnecessary further testing and treatment and imposes a burden on the child, family and the health care system.
Laron
Zvi
Z
Endocrinology & Diabetes Research Unit, Schneider Children's Medical Center of Israel, WHO Collaborating Center for the Study of Diabetes in Youth, Sackler Faculty of Medicine, Tel Aviv University, Israel. laronz@clalit.org.il
Bidlingmaier
Martin
M
Strasburger
Christian Joseph
CJ
D000365:Age Determination by Skeleton; D000886:Anthropometry; D001827:Body Height; D002352:Carrier Proteins / Q000032:analysis*; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000379:methods; D054439:Ghrelin / Q000235:genetics; D006128:Growth; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics; D019382:Human Growth Hormone / Q000032:analysis* / Q000172:deficiency* / Q000235:genetics; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D018013:Receptors, Neuropeptide / Q000235:genetics; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics; D011986:Receptors, Somatotropin / Q000235:genetics; D012680:Sensitivity and Specificity; D013004:Somatostatin / Q000235:genetics
D002352:Carrier Proteins; D054439:Ghrelin; D018969:Insulin-Like Growth Factor Binding Proteins; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D011986:Receptors, Somatotropin; D019382:Human Growth Hormone; D013004:Somatostatin; D007334:Insulin-Like Growth Factor I; D013007:Growth Hormone-Releasing Hormone; C048250:somatotropin releasing hormone receptor; C051815:somatotropin-binding protein