RESUMEN
OBJECTIVE AND IMPORTANCE: This case demonstrates a relationship between hydrocephalus with a huge diverticulum of the third ventricle and high serum levels of somatomedin-C. Somatomedin-C levels become high when the secretion of growth hormone from the adenohypophysis increases, and previous reports state that hydrocephalus decreases the secretion of growth hormone. CLINICAL PRESENTATION: The patient suffered from diabetes mellitus and obesity, and serum somatomedin-C levels were high. A pituitary adenoma or ectopic growth hormone-producing tumor was suspected. Magnetic resonance imaging did not reveal either of these abnormalities but indicated hydrocephalus with a diverticulum of the third ventricle. INTERVENTION: After ventriculoperitoneal shunt placement, the blood glucose and serum somatomedin-C levels of the patient decreased toward normal. Six months later, the shunt tube became obstructed and serum somatomedin levels increased. The levels decreased again after shunt revision. CONCLUSION: To our knowledge, this is the first published report of obstructive hydrocephalus with a diverticulum of the third ventricle compressing the hypothalamus and increasing the serum levels of somatomedin-C.