Early GH retesting worthwhile in children with isolated deficiency

By Eleanor McDermid
Growth Horm IGF Res 2017; 34: 31–37
01 June 2017

medwireNews: A substantial proportion of children with isolated growth hormone deficiency (IGHD) have a normal result when retested just 1 year later, report researchers.

By contrast, all the 95 patients in their study who had multiple pituitary hormone deficiency still had a subnormal GH stimulation response when retested after 1 year of GH therapy, say Dogus Vuralli (Hacettepe University, Ankara, Turkey) and team. They therefore suggest that retesting is unnecessary in these patients.

Several factors predicted which IGHD patients would have a normal result at retest, which occurred in 40.6% of 170 patients.

One of these was having a relatively mild deficit at the initial test, with 50.0% of patients with a peak GH level between 5 and 10 ng/mL having a normal result at retest. However, the team stresses that this also occurred in 19.2% of patients with an initial GH level below 5 ng/mL.

Another factor was age at the initial test, with patients aged 9 years or older being sixfold more likely than younger patients to have a normal retest result. Also, patients with a poor response to their first year of GH treatment, with a height standard deviation score increase of less than 0.61, had a fourfold increased likelihood of a normal GH stimulation response at the end of that year.

“Therefore, the early reevaluation of patients with a lower height gain in the course of GH treatment might be beneficial, either to prevent an unnecessary exposure to GH treatment or to apply a more effective dose of GH”, write Vuralli and team in Growth Hormone & IGF Research.

They also found that patients with normal findings or anterior hypoplasia alone on magnetic resonance imaging of the pituitary had a significantly increased likelihood of a normal GH stimulation retest, suggesting that such patients “may be good candidates for the reevaluation of GH secretory status early in the course of GH treatment during childhood, long before they reach their final growth height.”

Finally, pubertal status had an important influence on the likelihood of a normal retest result, with this occurring in 34.8% of patients who entered puberty between the initial test and the retest, 59.4% of those who had sex steroid priming and in 60.0% of those who were pubertal at the initial test, compared with just 2.7% of patients who remained prepubertal throughout.

“Therefore, priming with sex steroids is an important tool to differentiate between normal and abnormal GH secretions”, say the researchers.

They suggest that sex steroid priming prior to GH stimulation might be helpful in pubertal-age patients who have not yet entered puberty. “Otherwise, it may be recommended to reevaluate these patients during puberty.”

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