RESUMEN
Fanconi-Bickel syndrome is a rare inherited disease characterized by the combination of hepatorenal glycogen accumulation, proximal renal tubular dysfunction and impaired utilization of glucose and galactose. The first symptoms of the disorder are recognized in late infancy as clinical characteristics appear. Therapeutic approach is mainly conservative with supplements of calcium, phosphate and vitamin D and small frequent feedings to avoid hypoglycemia. We report 1 clinical case of very early diagnosis, a 19 days old baby girl, in which the first clinical sign of the disease was the detection of glycosuria and vomits. Serum alkaline phosphatase levels were very high without rickets. The patient presented postprandial hyperglycemia and fasting hypoglycemia. A complete 24-hour glucose profile was obtained using a continuous glucose monitoring system in real time, which was fundamental not only for the diagnosis but also for the prevention of hypoglycemia. She received frequent small meals, galactose-free milk diet, and oral intakes of calcium, phosphorum, bicarbonate and vitamin D supplements with good evolution and normal height and weight gain.