Article

Pediatric Research (1973) 7, 71–74; doi:10.1038/pr.1973.310

Effect of Levodopa (L-Dopa) on Serum Growth Hormone in Children with Short Stature

Zaven H Chakmakjian1, James F Marks1 and Chester W Fink1

1Weinberger Endocrine Laboratory, Departments of Medicine and Pathology, Baylor University Medical Center, and Department of Pediatrics, University of Texas Southwestern Medical School, Dallas, Texas, USA

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Abstract

Extract: The diagnostic usefulness of levodopa (l-dopa) as a provocative agent for stimulating growth hormone (GH) release was investigated in 22 children with short stature. Complete endocrine evaluation showed 17 to have normal pituitary function (group I) and 5 GH deficiency (group II). Serial serum GH measurements were made under basal conditions after arginine infusion, insulin hypoglycemia, and single dose oral administration of l-dopa (100–500 mg). Mean GH levels after l-dopa in group I were, in nanograms per milliliter: 0 min, 4.8; 30 min, 7.0; 60 min, 16.5; 90 min, 12.6; 120 min, 8.4; 150 min, 3.2; 180 min, 1.9. A significant GH rise was seen in 15 of 17 children, but a normal response as defined in the text was observed in 13 of 17. Peak GH response occurred between 30 and 120 min. Mean peak GH responses to l-dopa were 21.3, arginine 25.2, and insulin 21.3. The two nonresponders to l-dopa in group I showed normal GH response to insulin. The response to arginine was normal in one and partial in the other. Group II subjects showed no GH response to the three agents. Side effects to l-dopa were minimal and usually limited to temporary nausea. By virtue of its ready availability and simplicity of administration, the l-dopa test appears to be a good means of determining GH reserve.

Speculation: l-dopa administered as a single oral dose seems to be a simple and valid agent for evaluation of pituitary GH reserve.

Keywords:

l-dopa; dwarfism; growth hormone; pituitary