Basal hormonal evaluation revealed normal levels of T3, T4, TSH (thyroid stimulating hormone), CORT (8 am and 8 pm), ACTH (adrenocorticotropic hormone), and IGFBP3 (insulin‐like growth factor binding protein), but decreased level of IGF‐1 (insulin‐like growth factor‐1; 33.2 ng/ml, reference range >55 ng/ml), which suggested IGF‐1 deficiency. The gene discussed is IGFBP3; the disease is hyperinsulinemic hypoglycemia, familial, 4.