Usefulness of GnRH infusion test in the diagnosis of boys with delayed puberty

GRINSPON R; GOTTLIEB S; REY R; KESELMAN A; MARTÍNEZ A; BALLERINI MG; DOMENÉ H; ROPELATO MG

Lima, Perú

Congreso; XX REUNION ANUAL SOCIEDAD LATINOAMERICANA DE ENDOCRINOLOGIA PEDIATRICA.; 2008

Sociedad Latinoamericana de Endocrinología Pediátrica (SLEP)

Differential diagnosis between hypogonadotropic hypogonadism (HH)and constitutional delay of puberty in boys who present with delayed or arrested puberty is controversial. The aim of this study was to evaluate the usefulness of  GnRH infusion test to predict HH in boys with delayed/arrested puberty. Thirty-five boys (10.8.24.8 yr),(30 with absence of and 5 with arrested puberty)were submitted to IV GnRH infusion (0.83 ug/min for 120 min). LH and FSH (IFMA)were determined at 0,15,30,45,60 and 120 min.Final diagnosis of complete HH (n =17)was done with testes <4 ml at 18 yr,and partial HH (n =11)when testes enlargement started but remained arrested for at least 1 yr or did not reach 15 ml. ROC curves were used to determine optimal cut-off points. LH peak occurred between 15 and 120 min,and FSH peak at 120 min.LH peak <5.8 IU/L showed a 95.8 %positive predictive value (PPV)for HH,with 82%sensitivity (S)and 85%specificity (Sp); the positive likelihood ratio (LR +)was 5.8.FSH peak <4.6 IU/L showed similar results.Interestingly,basal FSH <1.15 IU/L had a 100%PPV for HH,(S:64.3%,Sp:100%).Peak LH >5.8 IU/L and FSH >4.6 IU/L in the same patient detected constitutional delay of puberty with 85.7%S and 89.2%Sp;LR +was 8. In conclusion,in a boy with delayed or arrested puberty,a GnRH infusion test is useful to confirm HH when peak of LH and/or FSH <cut off.When both peak values are above cut-off in the same patient,constitutional delay of puberty can be diagnosed with high accuracy.Finally,basal FSH <1.15 IU/L confirms HH and no further test is necessary.