title: Plasma IGF-I is a useful marker of growth hormone deficiency in adults.
abstract: Diagnosing growth hormone deficiency in adults is difficult. Provocation tests are most commonly used for the diagnosis with the insulin-induced hypoglycemia test nowadays considered as the "gold standard". The role of IGF-I concentrations in diagnosing growth hormone deficiency in adults is under discussion. In 58 adult patients with proven growth hormone deficiency, the sensitivity and specificity of IGF-I concentrations in relation to growth hormone deficiency were evaluated. Reference values of plasma IGF-I were obtained from 53 healthy volunteers. Using a calculated cut-off concentration of 15 nmol/l we were able to demonstrate that IGF-I concentration is a reliable screening method for growth hormone deficiency. Using this cut-off point in a patient population younger than 40 years of age, sensitivity was 90% and specificity 89%. For patients exceeding the age of 40 years, sensitivity, specificity and positive predictive value were rather low, but the negative predictive value was as high as 90%, indicating that for patients over 40 years IGF-I concentrations above 15 nmol/l exclude growth hormone deficiency. In summary, under the age of 40 years measuring plasma IGF-I provides an useful tool to diagnose growth hormone deficiency, whereas above 40 plasma IGF-I values exceeding 15 nmol/l virtually exclude growth hormone deficiency.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, University Hospital Nijmegen, The Netherlands. J.Span@aig.azn.nl
authors.forename: J P
authors.initials: JP
authors.lastname: Span
authors.forename: G F
authors.initials: GF
authors.lastname: Pieters
authors.forename: C G
authors.initials: CG
authors.lastname: Sweep
authors.forename: L M
authors.initials: LM
authors.lastname: Swinkels
authors.forename: A G
authors.initials: AG
authors.lastname: Smals
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism; D015415:Biomarkers; D015992:Body Mass Index; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012016:Reference Values
chemical_list: D015415:Biomarkers; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I