Severe Hypernatremia Due to Central Diabetes Insipidus with Adipsia: Challenges in Management

Introduction:
Hypernatremia (serum sodium >145meq/L) is independently associated with increased mortality as high as 40-60%. Mortality correlates with the rapidity of the rise in sodium and the degree of severity.

Central Diabetes Insipidus (DI) associated with adipsia pose a unique management challenge, leading to recurrent hospital admissions due to hypernatremia. 

We report, a patient with Central DI who presented with severe hypernatremia following desmopressin non-compliance and inadequate water intake.

Case Description:
A 25-year-old female with a past history of obstructive hydrocephalous underwent ventriculoperitoneal shunt revision and had a complicated hospital course including new onset Central DI. The patient was discharged on desmopressin and a serum sodium of 148 meq/L. She presented to the hospital 3 days later with altered mentation, dehydration, and a heart rate of 124bmp. Other vital signs were stable.

CT head showed no acute intracranial abnormalities. Labs showed: serum sodium 190meq/L, serum osmolality 393mOsm/kg, urine sodium 44mEq/L, and urine osmolality 878mEq/L. She initially received IV isotonic fluid, and IV DDAVP, and later started on hypotonic fluid and oral DDAVP. Labs were monitored every 6 hours.

The patient didn’t have a sense of thirst, didn’t like the taste of water, and had a suboptimal response to oral DDAVP. Multiple measures were taken to stabilize her serum sodium: switched to DDAVP Nasal spray, placed alarms on her cell phone as a reminder to drink water, flavored powders were used to make the water palatable, and provided education on the importance of DDAVP, adequate water intake, and outpatient follow-ups.

The patient was safely discharged home after demonstrating the ability to maintain normal serum sodium on oral fluid intake and self-administered nasal DDAVP.

Discussion:
Thirst is a critical adaptive mechanism to protect against hypernatremia. Intense thirst may be present initially, but it dissipates as hypernatremia progresses and is absent in patients with adipsia. Destruction or improper functioning of osmoreceptors in the hypothalamus that controls the thirst mechanism can result in adipsia; this may result from a congenital malformation or acquired as in the case of stroke, trauma, or infection. It was most likely secondary to multiple intracranial procedures in our patient.

This case also highlights cerebral adaptation to chronic hypernatremia. Brain shrinkage is countered by an adaptive response initiated promptly and consists of solute gain (initial uptake of sodium and potassium, followed by the later accumulation of osmolytes; mainly myoinositol and the amino acid glutamine) by the brain that tends to restore lost water. This response leads to the normalization of brain volume and accounts for the milder symptoms of hypernatremia that develops slowly, as seen in this patient.

In conclusion, patients with Central DI associated with adipsia can pose a significant management challenge. This case highlights the importance of addressing all the barriers that affect patients’ compliance with DDAVP and ensuring adequate hydration to prevent recurrent hospital admission and associated morbidity and mortality.