Adipsic Hypernatremia Complicated by Hyperosmolar Hyperglycemic State and Extensive Venous Thromboembolism After Traumatic Brain Injury: A Case Report

Adipsic hypernatremia is a rare disorder characterized by impaired thirst perception despite severe hyperosmolality, most commonly resulting from hypothalamic dysfunction. Hyperosmolar hyperglycemic state (HHS) may further aggravate dehydration and electrolyte imbalance, increasing the risk of neurologic injury, acute kidney injury (AKI), and thromboembolic complications. Reports describing the coexistence of adipsic hypernatremia, HHS, and extensive venous thromboembolism are limited. A 42‐year‐old man with poorly controlled diabetes and recent traumatic brain injury presented with neurologic decline, severe dehydration without thirst, severe hypernatremia, HHS, and transient renal dysfunction consistent with prerenal injury. Persistent severe hypernatremia despite improvement in hyperglycemia, together with preserved urinary concentrating ability, supported adipsic hypernatremia. Further evaluation revealed extensive deep vein thrombosis (DVT) and bilateral pulmonary embolism (PE), while brain imaging showed only mild diffuse cerebral atrophy. The patient was treated with controlled volume and free‐water replacement, intravenous insulin therapy, anticoagulation, and close monitoring of serum sodium, glucose, renal function, and urine output. Gradual correction of hypernatremia resulted in significant improvement in neurologic manifestations, renal function, and metabolic abnormalities. Following stabilization, he was discharged on apixaban therapy with scheduled oral hydration instructions and outpatient follow‐up. This case highlights a possible synergistic interaction between adipsic hypernatremia and HHS, which may have contributed to severe hyperosmolar stress and extensive thromboembolic complications. Adipsic hypernatremia should be considered in patients with severe hypernatremia and absent thirst sensation, particularly after traumatic brain injury, even when neuroimaging findings are unremarkable.