Q: My son (aged 26 months) has a height of only 80 cms. We got growth hormone level done as his height is less as compared to other children. The result is 1.4 ng/ml. The weight of the child is 11 kg. What should we do?

A:Growth hormone (GH) level in blood fluctuates at different times, hence estimating the GH levels in a single blood sample taken randomly, after fasting, early morning or at night does not help in diagnosis of GH deficiency (GHD). Had the levels been more than 10 ng/ml, it would have ruled out the possibility of GHD, but the converse is not true. For that you have to estimate peak GH levels by giving agents like insulin, arginine, l-dopa, clonidine or similar pharmaceutical agents and estimate the GH levels several times a day, e.g., 0, 15, 30, 45, 60, 90, and/or 120 minutes after the administration of the drug. Peak GH levels less than 10 ng/ml in tests done like this suggest GH deficiency. Exercise and sleep tests are not very reliable in small children. Levels of GH in blood depends on normal function of body systems especially thyroid. Ensuring they are normal is essential before interpretation of these results.