medwireNews: The presence of hypothalamic–pituitary alterations on brain magnetic resonance imaging (MRI) may allow more confident diagnosis of growth hormone deficiency (GHD) in very young children, say researchers.

The team found that most children diagnosed with isolated GHD at less than 4 years of age and all those with multiple pituitary hormone deficiency (MPHD) had abnormal MRI findings. And all children diagnosed when younger than 12 months had abnormal scans.

Regardless of their age at diagnosis, all 31 children with MPHD had complex defects of the hypothalamic–pituitary region, such as ectopic posterior pituitary, with or without pituitary hypoplasia, and abnormalities of the pituitary stalk or midline.

“When complex defects of the [hypothalamic–pituitary] region are detected, the likelihood of GHD is so high that GH treatment can be started without the need to perform GH provocative tests”, say Valentina Pampanini (Karolinska Institutet and University Hospital, Stockholm, Sweden) and co-researchers.

“This approach would lead to a reduced cost-benefit ratio and earlier start of treatment.”

They suggest this would avoid the problems of using GH stimulation tests in very young children, including the lack of reference data for this age group. They note, however, that their study was retrospective, so cannot determine the predictive power of the MRI findings.

A further 37 children had isolated GHD. Of these, 35.1% had complex defects of the hypothalamic–pituitary region, 48.7% had pituitary hypoplasia (pituitary height ≤3 mm) and 16.2% had normal pituitary findings.

Regardless of whether they had MPHD or isolated GHD, children with complex defects were diagnosed at a younger age than those without complex defects, and had lower peak GH responses to stimulation.

Among patients with isolated GHD, the likelihood of normal findings differed by age at diagnosis. All five children diagnosed at younger than 12 months had abnormal findings (four had complex defects), as did all six diagnosed between 13 and 24 months (two with complex defects), whereas two of the 19 diagnosed between 25 and 48 months had normal findings, with seven having complex defects and 10 hypoplasia. Six children did not have a precise age at diagnosis on record.

The researchers suggest that children with normal MRI findings can undergo the usual diagnostic work-up.

“As MRI is already part of the diagnostic work-up of GHD, the approach we propose does not increase the burden for the patients and the cost-benefit ratio”, they write in Hormone Research in Paediatrics.

“This strategy allows the postponement of GH stimulation tests to an age when they can be more easily performed and interpreted.”

By Eleanor McDermid, Senior medwireNews Reporter

Horm Res Paediatr 2015; Advance online publication

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