In our own (PIVET, yet unpublished) studies on subfertile women we have regarded IGF-1 levels <20 nmol/L as representing the deficiency range and an IGFBP3/IGF-1 ratio ≥5.0 being consistent with AGHD, implying that such women will be likely to benefit from GH supplementation. The gene discussed is IGF1; the disease is hyperinsulinemic hypoglycemia, familial, 4.