1064 CHRONIC HYPONATREMIA AND MIDFACIAL HYPOPLASIA (MFH)

Abstract

Persistent hyponatremia (Na 126 mEq/L) was found in a 30 month old girl with typical features of MFH. Hyponatremia, serum hypoosmolality (250 mOsm/L), urine hyperosmolality (U/P osm 3:1) and continued urinary sodium excretion suggested the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Renal, adrenal, pulmonary and drug etiologies for SIADH were excluded. 5 mEq/kg hypertonic Na Cl resulted in less than expected rise in serum Na (115 to 120 mEq/L) and marked increase in urine Na excretion (26 to 95 mEq/L). Water loading (25 ml/kg D₅W) leading to serum osmolality fall from 250 to 227 mOsm/L or volume expansion (25 ml/kg 0.9% Na Cl iv) did not lead to formation of dilute urine (lowest U osm 686 mOsm/L). Also plasma ADH measured by radioimmunoassay did not fall to 0 (lowest value 1.4 μlU/ml). These findings suggested resistance of hypothalamic center to afferent stimuli from volume and osmoreceptors which normally inhibit ADH release. Only fluid restriction (40 ml/kg/24h) successfully raised serum Na to normal. Serum Na returned to hyponatremic levels on 3 days ad lib diet. MFH has been associated with deficiencies of anterior and posterior pituitary hormones. This report documents persistent ADH excess and further suggests hypothalamic abnormalities in MFH.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD