Category: Pituitary Disorders/Neuroendocrinology
A critical regulator of water homeostasis is the osmoreceptor in the anterior wall of the 3rdventricle. In response to hypernatremia, the osmoreceptor triggers the sensation of thirst to increase water intake and the release of ADH to decrease urinary water loss. Conversely, infarction of the osmoreceptor disrupts the thirst mechanism and ADH secretion, a dual defect known as adipsic diabetes insipidus. This is a devastating sequela of cerebral aneurysm clipping involving the anterior communicating (ACOM) artery.
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A 43 year old man with hypertension and type 2 diabetes presented with an acutely worsening headache. A subarachnoid hemorrhage from an ACOM aneurysm was diagnosed and treated with clipping and endovascular coiling. Subsequently, the patient developed adipsic diabetes insipidus, which was treated with ddAVP tablets (0.2mg TID) and variable fluid intake (1-3 L/day) depending on weekly sodium lab checks and daily body weights. His management was confounded by a cognitive defect following the subarachnoid hemorrhage, the lack of air conditioning at home, the occasional osmotic diuresis caused by hyperglycemia, and his aversion to water and denial of thirst even when severely hypernatremic. Despite weekly sodium lab checks as an outpatient, he had frequent episodes of severe hypernatremia (to 168 mEq/L) causing altered mental status, necessitating 5 hospitalizations over 12 months.
To implement sodium self-monitoring, we acquired a handheld blood analyzer (iSTAT) with unrestricted supplies of cartridges, for free, using Abbott’s Physician-Guided Program (firstname.lastname@example.org). The spouse was trained to collect fingerstick samples into a microhematocrit capillary tube (heparinized; 0.07cc; Fisher Cat. 22-362566). A plastic dropper was adapted as a blower to facilitate sample loading into the cartridge. After validating the technique and the iSTAT readout against simultaneous lab values, we prescribed a sliding scale for water intake based on iSTAT sodium levels every 2-3 days. We used concurrent iSTAT glycemic readout to account for the pseudo-hyponatremic effect of hyperglycemia. Since the implementation of the above, patient’s sodium levels have remained primarily between 139-153 mmol/L for 6 months, and hospitalization have been avoided.
To our knowledge this is the first use of a portable blood analyzer to treat an adult with adipsic diabetes insipidus. The use of a portable blood analyzer improved treatment and decreased hospitalizations. With the improved availability of portable blood analyzers, this technology can be utilized for other difficult to manage diseases.
University of California, San Diego
Associate Professor of Medicine in the Division of Endocrinology, Diabetes, & Metabolism at the University of California San Diego and San Diego VA Health System.