OR37-3 GnRH agonist test versus inhibin B and basal LH for distinguishing constitutional delay of growth and puberty from isolated hypogonadotropic hypogonadism in boys

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: OR37-Pediatric Endocrinology: HPG Axis Disorders
Clinical
Monday, June 17, 2013: 11:15 AM-12:45 PM
Presentation Start Time: 11:45 AM
Room 102 (Moscone Center)
Gerhard Binder*, Roland Schweizer and Regina Braun
University Children's Hospital, Tuebingen, Germany
Background

The clinical distinction between constitutional delay of growth and puberty (CDGP) and isolated hypogonadotropic hypogonadism (IHH) in males with delayed puberty is difficult. Definitive diagnosis by endocrine testing is important for counselling and especially, for treatment in time.

Aim

We assessed the accuracy of the GnRH agonist challenge in comparison to basal inhibin B (INHB) and basal LH for diagnosing IHH in a prospective study.

Patients

Prepubertal males (n=50) with an age between 13.6 and 16.5 years and a testicular volume ≤ 3.5 ml were recruited. CDGP was defined by reaching a testicular volume ≥ 8 ml during an 18 months follow-up while a testicular volume < 8 ml after 18 months was taken as indicative of the presence of IHH. INHB was measured by ELISA (Beckman Coulter, Inc, U.S.A), LH by CLIA (Siemens Health Care Systems, Germany). We assessed the test validity of basal LH and basal INHB as well as of stimulated LH at 4h (LH(4h)) after a Triptorelin 0.1 mg challenge.

Results

The cohort comprised 42 boys with CDGP and 8 with IHH. Each, basal LH<0.3 IU/L or LH(4h)<5.6 IU/L or INHB<112 pg/mL had a sensitivity for the detection of IHH of 100%. However, only LH(4h)<5.6 IU/L had a specificity of 100% while specificities of basal LH<0.3 IU/L (86%) and of INHB<112 pg/mL (92%) were lower. The combination of both basal parameters, LH<0.3 IU/L plus INHB<120 pg/mL, increased the specificity to 95%.

The area under the curve of ROC plot analysis for diagnosing IHH was greatest for LH(4h)<5.6 IU/L (100%) followed by INHB<112 pg/mL (98%; 95%-CI: 96%-100%) and basal LH<0.3 IU/L (95%; 95%-CI: 90%-100%).

Conclusions

The LH response 4 hours after GnRH agonist challenge has an excellent sensitivity and specificity to diagnose IHH in prepubertal boys with delayed puberty. In the absence of GnRH agonist challenge, the combined judgement of basal LH and INHB is a valid alternative with a slightly lower specificity. We recommend the GnRH agonist challenge to diagnose IHH in boys with delayed puberty.

Nothing to Disclose: GB, RS, RB

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm