Potential indication of chemotherapy for hypodipsia and arginine vasopressin deficiency secondary to hypothalamic-pituitary Langerhans cell histiocytosis: a case report and literature review.

Hypothalamic-pituitary Langerhans cell histiocytosis (HP-LCH) is often associated with arginine vasopressin deficiency (AVD). Patients with AVD caused by HP-LCH rarely develop an impaired osmotic threshold for thirst (OTT). Improvement in OTT among such patients has not been reported in the literature. To our knowledge, here we report the first case of AVD due to HP-LCH in which hypodipsia resolved during chemotherapy. A nine-year-old Japanese girl presented with polydipsia, polyuria, anorexia, and hypernatremia (149.8 mEq/L) and was diagnosed with AVD secondary to HP-LCH. Visual analog scale examination showed a reduced OTT following the water deprivation test. During chemotherapy for Langerhans cell histiocytosis (LCH), serum sodium concentrations became stable between 138.9 and 142.9 mEq/L under the replacement of desmopressin. Repeated visual analog scale examinations showed that she experienced a sense of thirst at a serum sodium concentration of 142.3-144.6 mEq/L, at which she did not experience any thirst prior to the initiation of chemotherapy. These data suggest that chemotherapy directly improved the OTT in our patient. Improved mechanical compression or infiltration of the hypothalamus related to OTT may lead to the recovery of the sense of thirst. This report highlights the potential role of chemotherapy for solitary HP-LCH in patients with hypodipsia and AVD.

Hypodipsic-hypernatremia syndrome in an adult with polycythemia: a case report.

BACKGROUND: Hypernatremia is a very common electrolyte disorder and is frequently encountered in out-patient as well as in-hospital settings. We describe an adult who was found to have unexplained relative polycythemia and episodic hypernatremia. A diagnosis of idiopathic hypodipsic-hypernatremia syndrome was made and the patient was managed with a water-drinking schedule. CASE PRESENTATION: A 24-year-old South African-Indian man was found to have polycythemia in association with episodes of hypernatremia. Investigations indicated that he had relative polycythemia. He experienced no thirst at a time when his serum sodium concentration was found to be 151 mmol/L. Further testing indicated that his renal response to arginine vasopressin was intact and magnetic resonance imaging of his brain revealed no hypothalamic lesions. A diagnosis of idiopathic hypodipsic-hypernatremia syndrome was made and he was managed with a water-drinking schedule that corrected his hypernatremia. CONCLUSION: Hypodipsia should always be considered when a patient without physical or cognitive disability presents with unexplained episodic hypernatremia or with relative polycythemia.

MRI of lobar holoprosencephaly in a cat with hypodipsic hypernatraemia.

CASE SUMMARY: A 2-year-old neutered female domestic shorthair cat presented with a history of hypodipsia, recurrent hypernatraemia, pelvic limb ataxia and tremor. The serum arginine vasopressin level was low for the serum osmolality. MRI of the brain revealed a failure of separation of the cerebrum, which manifested as absence of the rostral part of the corpus callosum, fornix and septum pellucidum, thus resulting in a single fused ventricle. The diagnosis was lobar holoprosencephaly with hypodipsic hypernatraemia. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first description of the MRI characteristics of lobar holoprosencephaly in a cat. This report suggests that MRI examination should be considered for precise diagnosis of hypodipsic hypernatraemia in young cats.

Quench the thirst: lessons from clinical thirst trials.

Thirst, as a symptom, has long been considered the most prevalent clinical complaint patients voice in healthcare settings. Yet, rarely have researchers examined thirst by its correlation with physiologic factors. This review was undertaken to examine the relationships between thirst ratings and factors mediating its primary physiologic correlates: plasma osmolality (pOsm) and arginine vasopressin peptide (AVP). A literature search was undertaken to identify clinical studies in human subjects that investigated the relationship of thirst to specific physiologic thirst-related correlates and associated thirst mediators. Thirst was induced in 17 selected clinical studies by hyperosmolar infusion, through water deprivation or exercise weight-loss regimens. Positive linear relationships between the subjects' thirst ratings and rising serum pOsm levels confirmed the presence of intact osmotic thirst drives. However, there were significant variations in normal compensatory rises in AVP levels that followed the rises in plasma osmolality after the subjects were exposed to cold, physical pre-conditioning and water immersion tests. Notably, older adults in the studies reported diminished thirst ratings. Weak correlations suggest that angiotensin II may play only a minor role in thirst mediation. Atrial natriuretic hormone's inhibitory effect on thirst was inconsistent. Findings indicated that older adults are at higher risk for profound dehydration due to sensory deficits along with failure to correct volume losses. The thirst trials results support the close correlation between serum pOsm values and patients' thirst ratings, with the exception of the older adult.

Semilobar Holoprosencephaly with Neurogenic Hypernatraemia: Two new cases.

Holoprosencephaly (HPE) is a developmental defect of the embryonic forebrain and midface. It is due to the non-cleavage of the embryonic forebrain into two cerebral hemispheres and the incomplete development of the paramedian structures. The overall prevalence is 1.31 per 10,000 births. The aetiology could be genetic, environmental, or both. HPE is classified into alobar, semilobar, and lobar subtypes based on the degree of separation of the cerebral hemispheres. We report two new cases of semilobar HPE with neurogenic hypernatraemia. Lack of thirst and hypodypsia associated with chronic hypernatraemia in patients with HPE is highly suggestive of neurogenic hypernatraemia. Early identification of neurogenic hypernatraemia is important as it improves with forced fluid therapy and does not require any medication.

Central diabetes insipidus and adipsia due to astrocytoma: diagnosis and management.

Adipsia and/or diabetes insipidus is rarely a direct complication of astrocytoma. We report a young man with recurrence of anaplastic astrocytoma who presented as severe hypernatremia. This case highlights key diagnostic and therapeutic challenges: (1) the interpretation of the response to exogenous vasopressin in a patient with steroid-induced hyperglycemia and (2) the potential risk of brain edema and herniation if excess water is prescribed along with vasopressin supplementation. The patient was successfully managed with prescribed fluid replacement, daily weights, and regular electrolyte monitoring but no exogenous vasopressin for 8 months until he succumbed to his tumor.

Hypernatremia secondary to post-stroke hypodipsia: just add water!

Disorders in water metabolism may occur in stroke patients. When hypernatremia arises in this setting, it is usually secondary to the development of central diabetes insipidus or it is the result of neurologic lesions that prevent patients from having free access to water. Much rarer are the cases of post-stroke hypernatremia caused by hypodipsia secondary to lesions of the thirst center. We report the case of a patient with severe hypernatremia, probably secondary to post-hemorrhagic stroke hypodipsia. The hypernatremia seen in this case was corrected by scheduling the patient's water intake.