Increased renal sensitivity to vasopressin in two patients with essential hypernatremia

Aspects cliniques des syndromes hypothalamiques idiopathiques : étude rétrospective et revue de la littérature

Hypothalamic obesity is usually induced by tumoral or genetic alterations such as craniopharyngioma or Prader-Willi syndrome, respectively. However, few cases have been reported without recognized etiology, this syndrome is also called idiopathic hypothalamic syndrome.

OBJECTIVES

To improve definition and frequency of complications associated with this syndrome.

POPULATION AND METHODS

A retrospective cohort study was performed in French endocrine paediatric departments and was associated with a literature review.

RESULTS

We report five cases of idiopathic hypothalamic syndrome. This syndrome is correlated with a high mortality (one of our five cases, 25% in the literature) by neurovegetative dysfunction (breathing or thermal alteration). Obesity began before six years old because of compulsive eating and resulted in social behaviour disorders. Abnormal endocrine secretions were characterized by early hyperprolactinemia, permanent but later somatotrope deficiency and 80% of thyreotrope deficiency. Puberty abnormalities included hypogonadotropic hypogonadism as well as precocious (one of our cases, three cases including literature) or normal puberty. Neurogenic hypernatremia and water and electrolytic disorders were also responsible of acute neurological alterations.

CONCLUSION

This largest study ever reported of idiopathic hypothalamic syndrome emphasizes the need of a multidisciplinary coordination to provide the best care of these patients.

The abnormal quinine drinking aversion in the Brattleboro rat with diabetes insipidus is reversed by the vasopressin agonist DDAVP: a possible role for vasopressin in the motivation to drink

The Brattleboro rat with hypothalamic diabetes insipidus (BDI) has an abnormal aversion to drinking quinine-adulterated water compared with normal rats of the parent Long Evans (LE) strain. This BDI animal tolerates marked hypovolemia and decreased body weight in preference to drinking the quinine-adulterated fluid, indicative of a reduced motivation to drink. Acute or chronic treatment of BDI rats with desamino-8D arginine vasopressin (DDAVP) restored to normal their drinking response to quinine solution. Partial restoration of fluid turnover in BDI rats with hydrochlorothiazide, which has an antidiuretic effect in diabetes insipidus (when vasopressin is absent), failed to abolish the abnormal drinking response to quinine-adulterated solution in 8 out of 12 animals. In contrast, induction of diabetes mellitus in LE rats, which resulted in a marked polydipsia and polyuria even though vasopressin was still present, did not impair the drinking response to quinine solutions. These results suggest that the abnormal drinking response to quinine-adulterated fluid in BDI rats is reversed by treatment with the vasopressin V2-receptor agonist DDAVP but is unlikely to be a consequence of the restoration of fluid turnover to normal levels by a renal action. A possible central action involving vasopressin and the motivation to drink is discussed.

The frequency and natural history of diabetes insipidus in children with Langerhans-cell histiocytosis

Diabetes insipidus is a well-recognized complication of Langerhans-cell histiocytosis (histiocytosis X), but its frequency and natural history are not well defined. Of 52 children with histiocytosis whom we studied, 12 (23 percent) had diabetes insipidus. Only two children had diabetes insipidus at presentation with histiocytosis, but the cumulative risk that it would develop during the first four years after the presentation and diagnosis of histiocytosis was found to be 42 percent. Diabetes insipidus occurred most often among children with multisystem disease and those with proptosis. To determine the natural history of diabetes insipidus in children with histiocytosis, we measured the response of urinary arginine vasopressin to water deprivation every six months in 21 children who did not have diabetes insipidus and who had had histiocytosis for less than four years. Five of the 21 children (24 percent) had subnormal responses during the initial test. One subsequently had spontaneous improvement in the functioning of the posterior pituitary, and diabetes insipidus subsequently developed in two, as it did in one of the children who initially had normal function of the posterior pituitary. Two of the children received irradiation to the pituitary within two to four weeks after diabetes insipidus developed, but they had no improvement in pituitary function. However, diabetes insipidus improved transiently during prednisolone therapy in one of these children and improved permanently after etoposide therapy in another child. We conclude that prospective study with the use of a simple water-deprivation test will allow partial defects of posterior-pituitary function to be detected in patients with histiocytosis and will permit a more appropriate evaluation of the effects of therapeutic intervention.

[Severe hypernatremia in acquired disorder of thirst and vasopressin regulation]

Three patients with severe adipsic hypernatremia (greater than 171 mmol/l) are presented. In two of them, hypernatremia occurred after the operation of a ruptured aneurysm of the A. communicans anterior, in one patient the cause of the disease remained obscure. Despite high plasma osmolality, all patients had low or undetectable plasma vasopressin levels, even throughout hypertonic saline infusion. Urine concentrating ability was partially maintained, suggesting activation of alternative extra- and intrarenal concentrating mechanisms or increased renal sensitivity to low vasopressin concentration. Nonosmolar stimulation (insulin-induced hypoglycemia) did increase vasopressin concentration only subnormally in the two patients tested. This finding might be due to an extended and complex dysfunction of the anterior hypothalamus rather than to a circumscribed defect of the osmoreceptor/thirst center or the supraoptic nuclei.