A child’s rate of growth in stature is also a sensitive measure of growth hormone status, Darzy notes. “In the absence of other etiologies for growth retardation, the presence of significant growth deviation over a 1-year period (ie, growth velocity below the 25th percentile) … is highly suggestive of clinical growth hormone deficiency.”10
Because growth hormone replacement therapy may not be safe for 1 to 3 years after cancer treatment (the peak-risk period for recurrence, during which time it could facilitate growth of uneradicated tumors), testing usually should not begin within the first year after treatment.10 Thereafter, if growth rate is appropriate for a patient’s pubertal status, Darzy advises that subsequent growth be closely monitored and growth hormone response to ITT be tested annually.10 A normal ITT result 10 years after radiation exposure “usually eliminates the need for further annual testing,” Darzy reports.10
Bryant Furlow is a medical journalist based in Albuquerque, New Mexico.
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