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Oral clonidine effectively, safely diagnoses pediatric GH deficiency
Among pubertal and prepubertal children with suspected growth hormone deficiency, the adrenergic agonist clonidine can accurately and safely diagnose the condition without steroid priming before the test, according to findings published in Clinical Endocrinology.
“Several stimulation tests for GH secretion have been proposed in the last 50 years,” Anastasia Ibba, MD, of SSD Endocrinologia Pediatrica e Centro Screening Neonatale, Ospedale Pediatric, Cagliari, Italy, and colleagues wrote in the study background. “The GH peak cutoff was initially set at 5-7 g/L. However, the choice of this single fixed cutoff level does not take into account the type of stimulus nor the variation of the response due to gender, age, puberty, BMI and other factors.”
In a retrospective study, researchers analyzed data from 327 children and adolescents (204 boys; median age, 11 years) with short stature and/or poor growth velocity seen at one of four Italian pediatric endocrine units between 2005 and 2013. All children underwent a GH stimulation test with clonidine, administered at a dose of 0.15 mg/m² body surface [square root (height (cm) x weight (kg)/3,600 orally]. Clonidine was measured in the morning following an overnight fast; GH determination was made through blood samples collected at 0, 30, 60, 90 and 120 minutes. Researchers stratified children by pubertal stage to assess prepubertal vs. pubertal children with and without GH deficiency. The researchers found that the highest serum GH ranged from 0.07 μg/L to 55.7 μg/L (median, 11.1). The GH peak after clonidine treatment was less than 7 μg/L. Within the cohort, 87 children were diagnosed with GH deficiency, including 37 cases classified as organic and 50 designated as idiopathic. The 11 patients in whom the clonidine test failed (six prepubertal and five pubertal) responded normally to a second GH stimulation test, regardless of pubertal status (P = .66; 3.3% false-positive rate).
Children with GH deficiency had a lower GH peak (3.8 μg/L) vs. children without GH deficiency (13.4 μg/L; P < .0001). Children with GH deficiency also had a lower median baseline insulin-like growth factor level vs. those without the condition (P < .0001), according to researchers.
In a separate analysis on the effect of puberty in children with and without GH deficiency, researchers observed no difference in the median GH peak between prepubertal and pubertal children.
“This study demonstrates that, [when] using a validated cutoff of 7 μg/L, [the clonidine test] is reliable in the diagnosis of GH [deficiency] in children and adolescents, and that steroid priming may not be required,” the researchers wrote. “The oral [clonidine test] is safe and simple to perform and may be used as the first GH stimulation test in the evaluation of short children with suspected GH [deficiency].” – by Jennifer Byrne
Disclosures: The authors report no relevant financial disclosures.