Growth Hormone usually decreases following an elevation in blood glucose after a meal. It is usually increased during sleep or during starvation. It causes both retention of sodium and potassium which are required for growth metabolism.

Elevated GH levels increase IGF-1 blood levels. Because IGF-1 levels are much more stable over the course of the day, they are often a more practical and reliable measure than GH levels. Elevated IGF-1 levels almost always indicate acromegaly