Shorter L-DOPA test for growth hormone deficiency shows promise but raises accuracy concerns

Shortening the L-DOPA provocative test for diagnosing growth hormone deficiency (GHD) in children to 90 minutes is feasible but reduces the test’s specificity, especially when using the higher international growth hormone cut-off (10 ng/mL), according to a study.

The research analyzed 267 tests from 256 children, exploring the effects of using different growth hormone peak thresholds: 8 ng/mL (the Italian standard) and 10 ng/mL (the international standard).

The results showed that the growth hormone peak often occurred at 60 minutes. Although shortening the test to 90 minutes maintained a high sensitivity, it reduced specificity, particularly when using the 10 ng/mL cut-off. This reduction in accuracy affected only a small percentage of tests: 1.1% when using the international threshold and 2.6% with the Italian standard.

The researchers concluded that shortening the L-DOPA test to 90 minutes could potentially save time but may compromise its accuracy, particularly with higher GH cut-offs.

Reference
Castelli B, De Santis R, Carrera S, et al. L-DOPA Test in the Diagnosis of Childhood Short Stature: Evaluation of Growth Hormone Peaks Over Time. Endocrinol Diabetes Metab. 2024;7(5):e70000. doi: 10.1002/edm2.70000. PMID: 39211993; PMCID: PMC11362654.