Magnetic resonance imaging and clinical findings in a miniature Schnauzer with hypodipsic hypernatremia.

A 6-month-old miniature Schnauzer presented with hypernatremia and clinical signs of vomiting, diarrhea, inappetence, and lethargy. The dog did not consume water on its own. Hypernatremia and the related clinical signs were resolved by fluid administration. Endocrinological investigations and urinalysis excluded the possibility of diabetes insipidus and hyperaldosteronism. Therefore, the dog was diagnosed with hypodipsic hypernatremia. Magnetic resonance imaging revealed dysgenesis of the corpus callosum and other forebrain structures. On the basis of these findings, congenital brain malformation associated with failure of the osmoreceptor system was suspected.

Successful treatment with hydrochlorothiazide and amiloride in an infant with congenital nephrogenic diabetes insipidus.

We report a 9-month-old male Latino infant with congenital nephrogenic diabetes insipidus (NDI) who presented with hypernatremic dehydration aggravated by severe gastroenteritis. Initially, the infant was managed with intravenous fluids followed by standard 20 cal/ounce formula and pharmacological therapy, resulting in normalization of his serum sodium level. While hydrochlorothiazide therapy alone or in combination with prostaglandin inhibitors or amiloride has been successful in children and adolescents, this is the first report of the successful use of hydrochlorothiazide and amiloride in an infant with congenital NDI.

Hypodipsic hypernatremia and hypertriglyceridemia associated with cleft lip and cleft palate: a new hypothalamic dysfunction syndrome?

We report on a 4-month-old girl with congenital hypodipsic hypernatremia resulting from decreased sensitivity of the hypothalamic osmoreceptors with increased tonicity in association with hyperlipemia and cleft lip and cleft palate. We postulate that the link among these various derangements is hypothalamic dysfunction.

Chronic hypernatremia from a congenital defect in osmoregulation of thirst and vasopressin.

An infant with microcephaly and delayed development was found to have chronic asymptomatic hypernatremia. Computerized brain tomography disclosed dysplasia of the midline structures, septum pellucidum and corpus collosum. Evaluation revealed defective osmoregulation, hypothalamic hypothyroidism, and hypogonadotropinism. He showed no desire to drink at plasma osmolalities over 330 mOsm/kg. His plasma vasopressin levels (less than or equal to 1.4 pg/ml) were inappropriately low relative to his high levels of plasma osmolality (greater than or equal to 310 mOsm/kg), which might be accounted for by either deficient neurohypophyseal vasopressin stores or disturbance of the hypothalamic osmoreceptors governing vasopressin. The first possibility was ruled out by demonstrating normal vasopressin response (167 pg/ml) to nonosmotic (emetic) stimulation. Under baseline conditions, his urine was concentrated up to 747 mOsm/kg and urine volume was low. With water loading, maximal water diuresis developed (urine osmolality 68 mOsm/kg), but his plasma osmolality remained in the hyperosmolar range (312 mOsm/kg). Treatment with a vasopressin analogue, desamino-D-arginine vasopressin, and forced hydration restored plasma osmolality and plasma sodium to normal. These findings indicate a severe defect in the hypothalamic osmoreceptors controlling thirst and vasopressin secretion with normal vasopressin stores and preserved vasopressin responsiveness to nonosmotic stimuli. To our knowledge, this report provides the first documentation of selective osmoreceptor defect in conjunction with congenital dysplasia of midline brain structures.