It is a central diabetes insipidus (CDI) and a deficient or absent thirst response to hyperosmolality.
Adipsic diabetes insipidus (ADI) is a rare disorder.
It can occur after transcranial surgery for craniopharyngioma, suprasellar pituitary adenoma and anterior communicating artery aneurysm but also with head injury, toluene exposure and developmental disorders. It is often associated with significant hypothalamic dysfunction and complications like obesity, sleep apnea, thermoregulatory disorders, seizures and venous thromboembolism (VTE).
Diagnosis and management of these patients is quite challenging, even in expert hands.
In a review, Eisenberg and Frohman aim to provide an updated overview of this difficult clinical scenario.
They conducted a PubMed search for articles related to ADI. The search terms “adipsia,” “adipsic,” “thirst,” and “diabetes insipidus” were used to identify relevant literature.
ADI has been described in only approximately 100 patients. This rarity has limited the quality and quantity of literature to case reports, case series, and expert opinion. Diagnosis focuses on confirmation of CDI followed by documenting subnormal or completely absent thirst in response to a hypertonic stimulus. Among the described patients with ADI, the majority experience morbidity (e.g., severe hypernatremia, sleep apnea, venous thromboembolism [VTE], and obesity) and an increased mortality risk. Management focuses on frequent reassessment of daily prescribed water intake with fixed antidiuretic therapy (desmopressin) and comorbidity screening.
The complexity of patients with ADI provides a difficult challenge for clinicians. Prompt recognition of thirst disorders in patients with CDI should lead to appropriately regimented management strategies and can result in safe outpatient care for these unique patients 1).
Patients with ADI experience marked morbidity and mortality.
Twenty-five patients out of 26 (96%) patients developed diabetes insipidus after surgery for craniopharyngioma, a much higher incidence than after surgery for suprasellar (26/88, 30%, P < 0.001) or intrasellar pituitary tumours (9/66, 14%, P < 0.001). Hypertonic saline infusion identified abnormal thirst responses in five of the 16 craniopharygioma patients studied; all of the pituitary tumour patients had a normal thirst response. Three of the craniopharyngioma patients had adipsic diabetes insipidus whilst two had polydipsic diabetes insipidus 2).
A 52-year-old man with previous history of clipping of left posterior communicating artery aneurysm 20 years prior underwent microsurgical clipping of ACoA and left MCA aneurysms without any intraoperative complications. Shortly after surgery, he developed clear features of ADI with adipsic severe hypernatraemia and hypotonic polyuria, which was associated with cognitive impairment that was confirmed with biochemical investigations and cognitive assessments. He was treated with DDAVP along with a strict intake of oral fluids at scheduled times to maintain eunatremia. Repeat assessment at six months showed recovery of thirst and a normal water deprivation test. Management of ADI with cognitive impairment is complex and requires a multidisciplinary approach. Recovery from ADI is very rare, and this is only the second report of recovery in this particular clinical setting 3).