A reappraisal of diagnosing GH deficiency in adults: role of gender, age, waist circumference, and body mass index.
OBJECTIVE
The objective of the study was to reevaluate the diagnostic accuracy of GH peak after GHRH plus arginine test (GHRH+ARG) according to patients' age, body mass index (BMI), and waist circumference to diagnose GH deficiency (GHD).


METHODS
GH peak after GHRH+ARG and IGF-I levels reported as sd score.


METHODS
Subjects included 408 controls (218 women, 190 men, aged 15-80 yr) and 374 patients with hypopituitarism (167 women, 207 men, aged 16-83 yr).


RESULTS
In the (elderly) healthy subjects 15-25 yr old (young), 26-65 yr old (adults) and older than 65 yr, GH cutoffs were 15.6, 11.7, and 8.5 microg/liter, 11.8, 8.1, and 5.5 microg/liter, and 9.2, 6.1, and 4.0 microg/liter, respectively, in the lean, overweight, and obese subjects. Waist circumference was the best predictor of GH peak (t = -7.6, P < 0.0001) followed by BMI (t = -6.7, P < 0.0001) and age (t = -5.7, P < 0.0001). Based on the old (<9.1 microg/liter) and new GH cutoff, 286 (76.5%) and 276 (73.8%) of 374 hypopituitary patients had severe GHD. The receiving-operator characteristic analysis showed GH cutoffs in line with the third percentile or slightly higher results so that the prevalence of GHD increased to 90.1%.


CONCLUSIONS
The results of the current study show that waist circumference and BMI are the strongest predictors of GH peak after GHRH+ARG followed by age. However, the old cutoff value of 9.0 microg/liter was in line with the new cutoffs in 95% of patients.
Department of Molecular and Clinical Endocrinology, Section of Endocrinology, University of Naples Federico II, Italy, 80131 Naples, Italy. colao@unina.it
Annamaria
A
Colao
Carolina
C
Di Somma
Silvia
S
Savastano
Francesca
F
Rota
Maria Cristina
MC
Savanelli
Gianluca
G
Aimaretti
Gaetano
G
Lombardi
D000328:Adult; D001120:Arginine / Q000097:blood; D001794:Blood Pressure; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007018:Hypopituitarism / Q000097:blood / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D012016:Reference Values; D012307:Risk Factors; D012727:Sex Characteristics; D012964:Sodium / Q000097:blood; D055105:Waist Circumference
D008076:Cholesterol, HDL; D013006:Growth Hormone; D001120:Arginine; D012964:Sodium; D011188:Potassium