diagnosis and management of central diabetes insipidus in adults

Case 1

A 42-year-old female was diagnosed with a non-functioning pituitary tumor after presenting  with bitemporal hemianopia and fatigue. She had secondary AI, secondary  hypothyroidism, hypogonadotropic hypogonadism, and mild hyperprolactinemia. MRI  demonstrated a 33 * 22 * 22 mm pituitary tumor with suprasellar extension and compression  of the optic chiasm. Hydrocortisone and LT4 replacement were commenced, and she  underwent TSS

. On day one post-operatively, she developed increased polydipsia and polyuria. Urine output exceeded 400 mL/hour and the fluid balance  record showed a 24-hour intake of 4390 mL and urine output of 5685 mL. Urine specific  gravity was 1.005, urine osmolality 210 mOsmol/kg, plasma osmolality 304 mOsmol/kg and  plasma sodium 142 mmol/L

Case 2 :

A 23-year-old male presented with headaches and bitemporal hemianopia. He had signs of active acromegaly, and elevated growth hormone of 142 ug/L (reference 0.05-3.0) and IGF-1 of 150 nmol/L (reference 15-41). The remainder of his pituitary profile showed mild hyper prolactinemia, hypogonadotropic hypogonadism, and normal adrenal and thyroid function. MRI demonstrated a large pituitary tumor measuring 37 x 25 x 21 mm with suprasellar extension and optic chiasm compression. Trans sphenoidal surgery was performed. The patient had significant polyuria on the first post-operative day, with urine output exceeding 500 mL/hour. Urine output measured 6300 mL and fluid intake measured 3500 mL within the first 24 hours post-operatively. The patient was not thirsty, and biochemistry was not consistent with DI, with urine osmolality 243 mOsmol/kg, plasma osmolality 285 mOsmol/kg and plasma sodium 137 mmol/L.