The present invention provides a method for measuring growth hormone level in a human child, including a method of assessing pituitary-related growth hormone deficiency in a human child as a stand-alone test. The method includes the steps of oral administration of an effective amount of macimorelin to the child, collecting from the child two or three post-administration blood samples within a range of about 60 minutes after administration, and determining the level of growth hormone in the samples. The method can be used for diagnosing pituitary-related growth hormone deficiency in a child when the peak level of determined growth hormone in the samples is below a cut-off value.