Adipsic hypernatremia in two patients with AIDS and cytomegalovirus encephalitis

When Thirst Ceases to Exist: A Case Report and Literature Review of Adipsic Diabetes Insipidus Following Coil Embolization of a Ruptured Anterior Communicating Artery Aneurysm

Diabetes insipidus is a condition characterized by inappropriately dilute urine in the setting of serum hyperosmolality. The two predominant subtypes include central (from lack of vasopressin production) and nephrogenic diabetes insipidus (from renal resistance to circulating vasopressin). A common manifestation is the significant pursuant thirst from excessive polyuria. We present a case report and literature review of an infrequent variation of central diabetes insipidus known as adipsic (hypothalamic) diabetes insipidus, characterized by the absence of thirst, secondary to coiling of a ruptured anterior communicating artery aneurysm. Due to the loss of thirst, patients are at a heightened risk for hypernatremia and complications secondary to dehydration. Our patient's course was complicated by recurrent polyuria and hypernatremia, requiring a fixed-dose desmopressin regimen. On follow-up, only partial thirst sensation was restored. We provide a literature review to compare our case report to the scant literature available to broaden the awareness of this infrequent, perilous, manifestation.

Autoimmunity Related to Adipsic Hypernatremia and ROHHAD Syndrome

Specific antibody responses to subfornical organs, including Na_x antibody, have been reported in patients with adipsic hypernatremia of unknown etiology who do not have structural lesions in the hypothalamic–pituitary gland. The subfornical organ, also referred to as the window of the brain, is a sensing site that monitors sodium and osmotic pressure levels. On the other hand, ROHHAD syndrome is a rare disease for which the etiology of the hypothalamic disorder is unknown, and there have been some reports in recent years describing its association with autoimmune mechanisms. In addition, abnormal Na levels, including hypernatremia, are likely to occur in this syndrome. When comparing the clinical features of adipsic hypernatremia due to autoimmune mechanisms and ROHHAD syndrome, there are similar hypothalamic–pituitary dysfunction symptoms in addition to abnormal Na levels. Since clinical diagnoses of autoimmunological adipsic hypernatremia and ROHAD syndrome might overlap, we need to understand the essential etiology and carry out precise assessments to accurately diagnose patients and provide effective treatment. In this review, I review the literature on the autoimmune mechanism reported in recent years and describe the findings obtained so far and future directions.

Water, electrolytes, and acid-base alterations in human immunodeficiency virus infected patients

The clinical spectrum of human immunodeficiency virus (HIV) infection associated disease has changed significantly over the past decade, mainly due to the wide availability and improvement of combination antiretroviral therapy regiments. Serious complications associated with profound immunodeficiency are nowadays fortunately rare in patients with adequate access to care and treatment. However, HIV infected patients, and particularly those with acquired immune deficiency syndrome, are predisposed to a host of different water, electrolyte, and acid-base disorders (sometimes with opposite characteristics), since they have a modified renal physiology (reduced free water clearance, and relatively increased fractional excretion of calcium and magnesium) and they are also exposed to infectious, inflammatory, endocrinological, oncological variables which promote clinical conditions (such as fever, tachypnea, vomiting, diarrhea, polyuria, and delirium), and may require a variety of medical interventions (antiviral medication, antibiotics, antineoplastic agents), whose combination predispose them to undermine their homeostatic capability. As many of these disturbances may remain clinically silent until reaching an advanced condition, high awareness is advisable, particularly in patients with late diagnosis, concomitant inflammatory conditions and opportunistic diseases. These disorders contribute to both morbidity and mortality in HIV infected patients.

Central diabetes insipidus in an HHV6 encephalitis patient with a posterior pituitary lesion that developed after tandem cord blood transplantation

A 60-year-old myelodysplastic syndrome patient underwent tandem cord blood transplantation. The primary cord blood graft was rejected, and human herpesvirus 6 (HHV6) encephalitis developed after engraftment of secondary cord blood. Polyuria and adipsic hypernatremia were observed during treatment of the encephalitis. The patient died of bacteremia caused by methicillin-resistant Streptococcus epidermis. HHV6 infection in the posterior pituitary was confirmed on autopsy, as was infection of the hippocampus, but not of the hypothalamus. This is the first case report of central diabetes insipidus caused by an HHV6 posterior pituitary infection demonstrated on a pathological examination.

Altered fluid, electrolyte and mineral status in tropical disease, with an emphasis on malaria and leptospirosis

Fluid, electrolyte and mineral perturbations are prevalent features of tropical disease. Hemodynamic alterations, fever, nitrogen wasting, and changes in membrane transport and acid-base balance contribute to these perturbations. Models of malaria and leptospirosis have been used to show that common hemodynamic changes in tropical disease include decreased systemic vascular resistance, increased cardiac output and increased renal vascular resistance. Blood volume is initially increased, but it decreases as disease progresses. Response to fluid loading is decreased. Diabetes insipidus is occasionally observed in malaria. Hyponatremia occurs frequently in tropical diseases, as a result of increased levels of antidiuretic hormone (vasopressin), entry of sodium into cells, sodium loss and resetting of osmoreceptors. Natriuresis and kaliuresis are observed in patients with leptospirosis. Large amounts of sodium and potassium are lost in stool as a result of diarrhea. Hypernatremia is uncommon, whereas hypokalemia caused by hyperventilation is often observed (more frequently in patients with leptospirosis and kaliuresis). During severe tropical infective episodes, hyperkalemia results from intravascular hemolysis or rhabdomyolysis, and occasionally from decreased activity of Na+,K+-ATPase. Hypocalcemia, hypomagnesemia and hypophosphatemia are common features of both malaria and leptospirosis. Loss of magnesium in the urine is uniquely associated with leptospiral nephropathy. Hypozincemia and hypocupremia can also develop during tropical infection, and might interfere with a patient's immune response. These electrolyte and mineral perturbations are transient and quickly resolve when the disease is controlled.

Adipsic diabetes insipidus following pituitary surgery for a macroprolactinoma

Adipsic diabetes insipidus (ADI) is a rare condition in which thirst, an essential clinical feature for the prevention of hypernatraemic dehydration, is absent. We report the first case of adipsic diabetes insipidus to occur following surgery for a pituitary macroprolactinoma, with loss of both osmoregulated and baroregulated vasopressin release. Following extensive surgery for a vision threatening macroprolactinoma a 14-year-old boy developed profound hypernatraemia with absent thirst sensation. Detailed investigation, with hypertonic saline infusion and trimetaphan infusion, revealed absence of both osmoregulatory and baroregulatory release of vasopressin. We discuss the investigation and management of such patients and the physiology of hypothalamic-neurohypophyseal dysfunction in such patients.