For instance, in hypopituitary patients with three or more pituitary deficiencies, especially those who are younger than 40 years and have a BMI of below 25 kg/m2, a low serum IGF-I level (below the lower limit of the reference range for age), in the absence of catabolic conditions or liver diseases, is highly indicative of severe AGHD13–16. The gene discussed is IGF1; the disease is pituitary deficiency.