Introduction Recent literature shows that a basal early-morning serum luteinising hormone (LH) cut-off of ≥ 0,2 IU/L could be a simple and cost-saving tool for initial diagnosis of onset of early or normal puberty in girls before proceeding to LHRH testing. We investigated if this cut-off could also be used in the Dutch population using 2 different LH assays. 

Method We retrospectively revisited all LHRH tests conducted in over 100 girls aged 3-11 yrs in two laboratories (Atalmedial, Abbott Architect, n=48, 2015-2019 and LUMC, Roche ECLIA , n=64, 2012-2021) and evaluated the basal LH concentration versus the LH peak after stimulation with LHRH using local cut-offs for test positivity (Abbott Architect cut-off LH peak ≥ 6,0 IU/l; Roche ECLIA cut-off ≥ 5,0 IU/l).   

Results Both LH assays showed a positive predictive value of 94% for a positive LHRH test using a cut-off of ≥ 0,2 IU/L. In the Abbott Architect group 17 basal values ≥ 0,2 IU/L were found, with only one girl (7 yrs old) showing a basal LH of 0,6 IU/l combined with a LH peak < 6 IU/l after stimulation. This girl was lost from follow-up. In the Roche ECLIA assay 16 basal values ≥ 0,2 IU/L were found, with only one girl (8 yrs old) showing a basal LH of 0,4 IU/l combined with an LH peak < 5 IU/l after stimulation. Three months later this girl was started on depot GnRH treatment based on progressive clinical puberty signs. The negative predictive values of the basal LH for a negative LHRH test were 81% for the Abbott assay and 73% for the Roche assay.

Conclusions This study confirms the diagnostic value of the cut-off of 0,2 IU/L of basal LH in the Dutch population with positive predictive values of 94% for both LH assays, although evaluated in a relatively small group. A positive basal LH result obviates the need for an LHRH test, reducing the number of LHRH tests needed by 30% and increasing patient friendlyness and cost-effectiveness. A negative basal LH should always be followed by an LHRH test.