Diagnostic strategy for growth hormone deficiency: relevance of IGF-1 determination as a screening test.
BACKGROUND
Adult growth hormone (GH) deficiency must be diagnosed before prescribing therapeutic recombinant human GH. We studied the clinical relevance of a diagnostic strategy for growth hormone deficiency (GHD) using IGF-1 determination as a first step.


METHODS
In 2000 and 2001, we tested 142 adult patients with hypothalamo-pituitary disorders for somatotropic function using Insulin Tolerance Test (ITT), the reference test for the diagnosis of GHD, with concomitant Insulin-like growth factor-1 (IGF-1) determination, a marker of somatotropic function. Patients were classified as GHD (peak GH concentration<3 ng/ml with the ITT) or normal.


METHODS
Monocenter prospective study in a tertiary referral center.


RESULTS
GHD was diagnosed in 61 subjects. Using a ROC curve, a threshold IGF-1 concentration of 175 ng/ml yielded a negative predictive value of 89+/-5%. A diagnostic strategy with IGF-1 determination as the first step followed by ITT for patients with an IGF-1 concentration below 175 ng/ml missed five of the 61 GHD patients, avoided 46/142 ITT and reduced the cost of diagnosis by 15%.


CONCLUSIONS
We propose the use of a strategy consisting of IGF-1 determination followed, if below 175 ng/ml by confirmatory ITT to diagnose GHD in adults.
Hadjadj
S
S
Endocrinology, Diabetology, CHU de Poitiers, rue de la Milétrie, BP 577, 86021 Poitiers cedex, France. s.hadjadj@chu-poitiers.fr
Faure-Gerard
C
C
Ragot
S
S
Millet
C
C
Duengler
F
F
Torremocha
F
F
Chatellier
G
G
Bataille
B
B
Marechaud
R
R
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D013006:Growth Hormone / Q000172:deficiency*; D006801:Humans; D007027:Hypothalamic Diseases / Q000097:blood / Q000175:diagnosis*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010900:Pituitary Diseases / Q000097:blood / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
D015415:Biomarkers; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone