Effect of body mass index on peak growth hormone response to provocative testing in children with short stature.
BACKGROUND
Obesity is associated with decreased spontaneous and stimulated GH secretion, but the effect of body mass index (BMI) on results of GH stimulation testing in children with short stature is not known.


OBJECTIVE
The aim of the study was to determine the impact of BMI on peak GH to provocative testing in children with short stature.


METHODS
This was a retrospective review of provocative GH testing performed in 116 children 2-18 yr old in the ambulatory clinic of the Pediatric Endocrinology Unit at the Massachusetts General Hospital from 2004-2008.


METHODS
The main outcome measure was peak stimulated GH. Height, weight, IGF-I, and IGF-binding protein 3 were also measured.


RESULTS
In univariate regression analysis, BMI sd score (BMI SDS) was inversely associated with natural log (ln) peak GH to provocative testing (P = 0.002), whereas height SDS, ln IGF-I, and IGF-binding protein 3 were not significantly associated with ln peak GH. After controlling for age, gender, BMI, and pubertal status, BMI (P = 0.002) remained independently associated with ln peak GH. BMI SDS significantly influenced the likelihood of diagnosis of GH deficiency using peak GH cutoffs of 10, 7, and 5 microg/liter.


CONCLUSIONS
In children with short stature, BMI affects peak stimulated GH and should be considered when interpreting GH testing. Higher BMI SDS, even within the normal range, may lead to overdiagnosis of GH deficiency.
Stanley
Takara L
TL
Pediatric Endocrine Unit, Massachusetts General Hospital for Children and Harvard Medical School, Boston, Massachusetts 02114, USA. tstanley@partners.org
Levitsky
Lynne L
LL
Grinspoon
Steven K
SK
Misra
Madhusmita
M
D000293:Adolescent; D001827:Body Height / Q000502:physiology*; D015992:Body Mass Index; D001835:Body Weight / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000032:analysis / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000378:metabolism; D008297:Male; D011627:Puberty / Q000502:physiology; D012189:Retrospective Studies; D012727:Sex Characteristics
D018972:Insulin-Like Growth Factor Binding Protein 3; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I