A single sample subcutaneous luteinizing hormone (LH)-releasing hormone (LHRH) stimulation test for monitoring LH suppression in children with central precocious puberty receiving LHRH agonists

The effectiveness of LHRH agonist therapy in central precocious puberty dep ends upon suppression of LH secretion. The iv LHRH stimulation test is the gold standard for evaluating LH suppression, but is difficult to administer because it requires an iv line and multiple blood samples. We hypothesized that a sc LHRH test followed by a single LH measurement 40 min later mould be as accurate in the assessment of LH suppression in children receiving L HRH analogs. Eleven children received the sc test 1 month before or after t heir regularly scheduled iv LHRH treatment. Each child was receiving Lupron to suppress central puberty. Twenty-five comparisons of the iv and sc LHRH tests were completed over 14 months. We developed a clinical score for pub ertal suppression using Tanner staging, skeletal maturation, and growth vel ocity. The best correlation between this clinical score and the iv LHRH tes t was achieved when biochemical suppression was defined as peak LH less tha n 2 IU/L (100% sensitivity, 95% specificity). Using this definition, the sc LHRH test was 96% accurate (in 24 of 25 subjects), with a sensitivity of 7 5% and a specificity of 100% compared to the iv LHRH test. We conclude that the single sample sc LHRH test can accurately determine LH suppression and adequacy of LHRH agonist therapy in central precocious puberty.