Psychogenic Adipsia Presenting as Recurrent Functional Vomiting and Hypernatremia

Report of Case

A 46-year-old woman presented to the emergency department with complaints of intractable nausea and vomiting for 1 week. She reported that she had been unable to tolerate any liquids since being discharged from the hospital 1 week earlier with similar complaints. During this 1-week hospitalization, an upper endoscopy showed no structural abnormalities to explain her symptoms. Her home medications consisted of 4 mg of ondansetron orally as needed for nausea and 40 mg of oral pantoprazole daily for gastroesophageal reflux disease. She denied seizures, confusion, or delirium or use of diuretics, lithium, or cannabis. Her husband noted that she had a similar episode 7 years ago, which resolved after a 3-week hospitalization. He reported noticing that his wife had been feeling depressed during the preceding months.

On presentation, her vital signs revealed a temperature of 98.1 °F; blood pressure, 111/61 mm Hg; and heart rate, 109 beats/min. Physical and psychiatric examination findings were remarkable for dry oral mucosa, poor eye contact, and a flat affect. Structural examination findings were unremarkable. When asked to drink water at the bedside, the patient was noted to take small sips and immediately regurgitated the water mixed with saliva. Serum chemistry and urinalysis results on admission are presented in the Table. Urine electrolyte tests were ordered after fluid resuscitation, precluding accurate results. Results of magnetic resonance imaging of the brain with and without contrast were unremarkable.

After 3 days of intravenous hydration, the patient's sodium level stabilized to 145 mmol/L, and her creatinine improved to 1.3 mmol/L. After hormonal causes of hypernatremia were ruled out, the patient was evaluated by a psychiatrist, and major depression was diagnosed. She was prescribed 7.5 mg of mirtazapine to be taken daily. She subsequently reported an improved mood 2 days after taking the medication and could tolerate water orally. Improvements were noted in blood pressure (128/62 mm Hg), heart rate (76 beats/min), and serum levels of sodium (144 mmol/L), blood urea nitrogen (7 mmol/L), and creatinine (1.2 mmol/L). The patient was discharged on hospital day 7. Psychogenic adipsia was the discharge diagnosis after psych evaluation given her multiple episodes of symptoms, with vomiting attributed to the constellation of psychogenic adipsia. Follow-up was planned with her primary care physician.

Discussion

The diagnosis of psychogenic adipsia is one of exclusion and should be considered when a patient presents with hypernatremia and an impaired thirst drive. Given its rarity, there are no established diagnostic criteria for the syndrome. It should be considered in patients presenting with hypernatremia and dehydration in the absence of an inability to access water.^9,10 Renal urinary concentrating ability should be established to rule out central or nephrogenic diabetes insipidus via a water deprivation test with measurement of urine osmolality before and after administration of vasopressin. However, the presence of a very concentrated urine (osmolality >600 mOsm/kg) in the context of hypernatremia excludes diabetes insipidus and may obviate the need for water deprivation testing. Normally, the thirst drive is activated to keep serum osmolality between 275 and 295 mOsm/kg or when there is a 1% to 2% increase in plasma tonicity.^2,11 Central hypothalamic lesions (tumors or infiltrative diseases), which may affect osmoreceptors, vasopressin secretion, and thirst should be excluded with brain imaging.^2,10 Psychiatric assessment is vital in the diagnosis of psychogenic adipsia, as targeted treatment for underlying psychiatric problems has been shown to improve adipsia.^8,9

Previous reports of psychogenic adipsia have described patients presenting with isolated water avoidance,^8,12 fulminant psychotic symptoms,^6,7 and generalized fatigue.^10,13 Plasma osmolality was uniformly elevated in these cases, with concurrently elevated urine concentrations. Initial sodium correction may be managed through intravenous or oral fluids. Management of psychogenic adipsia varies according to the underlying psychiatric disorder. Hassan et al⁸ reported a patient with mild depressive symptoms who was able to tolerate water intake after 2 sessions of psychotherapy.⁸ Manning et al¹² reported improvement in thirst after a patient with adipsia following a stressful breakup was prescribed mirtazapine and clonazepam to decrease his anxiety.¹² In another case, a patient with psychotic depression characterized by mutism and adipsia required 10 sessions of electroconvulsive therapy for recovery of his speech and return of his thirst function.⁹

Conclusion

Psychogenic adipsia is a rare cause of hypernatremia. In our literature review, we found fewer than 10 cases. The current case highlights the osteopathic tenet of the body as a unit,¹⁴ demonstrating that an underlying psychiatric disorder may lead to dysregulation of water homeostasis. Early identification requires an understanding that biopsychosocial forces may lead to heterogenous presentations. Psychogenic adipsia may present as recurrent vomiting as described in the present case. Sodium correction with hypotonic fluids is the mainstay of initial treatment. Additionally, prompt psychiatric assessment and treatment should be undertaken to effectively address the underlying cause of adipsia.