A hypothalamic syndrome characterized by hypernatremia, adipsia, hyperprolactenemia and high threshhold for vasopressin release

Abstract

Adipsia with high threshhold for vasopressin release was diagnosed in a 9-year-old girl with episodes of muscular weakness,hypernatremia (Na 162-175 mEq/L) ↑ BUN, ↓ Hb and ↓ platelets,and urine osmolality 800-1400 mOsm/L.The levels of serum prolactin,FSH,LH, and estrogens (306 pg/ml) were high.She was obese with normal linear growth,and mentality,and Tanner II pubic hair. Thirst was not sensed even with serum osm.of 365 mOsm/L Prolactin decreased after hypertonic saline infusion (1640 to 1200 mIU/ml) and after L-DOPA (1600 to 600). Thyroid,and adrenal function,and muscle enzymes were normal.CT brain scans,the last one two years after initial symptomatology,were normal.The forcing of fluids (1500 ml/day) resulted in clinical improvement,normalization of serum Na,BUN,Hb and platelets and the appearance of regular menses.Prolactin,LH,and FSH did not change.The pathophysiologic implications will be discussed. It is postulated that the biochemical findings might have been caused by hypothalamitis (autoimmune?) with selective dysfunction of the thirst center,osmolar receptor-vasopressin release complex and the centers for LHRH and prolactin regulation.