Determination of insulin-like growth factor-I in the monitoring of growth hormone treatment with respect to efficacy of treatment and side effects: should potential risks of cardiovascular disease and cancer be considered?
Insulin-like growth factor (IGF)-I has proven to be important in the diagnosis of childhood-onset growth hormone (GH) deficiency (GHD). However, the variability of IGF-I should be taken into account before it can be used in a clinical setting. GH replacement therapy in GHD patients increases IGF-I into the normal range, although there is a large variation. Excessively high (supranormal) GH-induced IGF-I levels are associated with increased prevalence of side effects in adults with GHD. Consequently, at most centres, GH doses are titrated according to IGF-I levels in GHD adults. Whether or not this should also be done in children has not been established. Due to the known variability of IGF-I, individual changes in IGF-I must exceed approximately 35% to be sufficiently significant to warrant a dose adjustment. Novel epidemiological studies have suggested that higher IGF-I levels are associated with an increased risk of prostate, breast and colorectal cancer compared with lower IGF-I levels in otherwise healthy subjects. Consequently, life-time exposure to IGF-I should be considered in all patients treated with GH, and IGF-I should preferably be kept within normal age-related ranges in children as well as in adults.
Juul
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Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark. ajuul@post4.tele.dk
D000328:Adult; D002318:Cardiovascular Diseases / Q000139:chemically induced*; D016903:Drug Monitoring; D019382:Human Growth Hormone / Q000009:adverse effects* / Q000172:deficiency / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D009369:Neoplasms / Q000139:chemically induced*; D012307:Risk Factors; D012680:Sensitivity and Specificity
D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I