Hyponatremia Masquerading as Panic Symptoms in Bipolar Affective Disorder

To the Editor: Psychogenic polydipsiaassociated hyponatremia is a common electrolyte disorder seen in psychiatric patients.1 Most of psychogenic polydipsia have been reported in patients with schizophrenia2 and rarely in those with mood disorder.3 Here we report the case of a patient with bipolar affective disorder (BAD) who developed panic symptoms with polydipsia. A 68-year-old woman has suffered panic disorder (DSM-IV) since 6 months ago and thus been treated with escitalopram 10 mg/day and estazolam 2 mg/day. She was admitted for limited treatment response. No specific physical illness, nonpsychiatric medication use, and substance abuse were mentioned except increased water intake of about 6 L/day for 6 months. Upon admission, laboratory data showed plasma sodium levels of 121 meq/L (normal range: 136–145 meq/L) and plasma osmolality of 233 mOsm/L (normal range: 280–295 mOsm/L). Liver, renal, thyroid functions, and fasting blood sugar were within normal range. Her water intake was restricted to 2.5 L/day under careful supervision. Followed plasma sodium levels gradually reached the normal range within 1 week. Then her anxiety symptoms got much improved but evident manic symptoms characterized euphoric mood, talkativeness, increased psychomotor activity, and decreased sleep were noticed despite no escitalopram

treatment. On day 11, she was treated with valproate 1400 mg/day and discharged on day 25 with full recovery of manic episode. Her diagnosis was finally revised to BAD, current manic episode. The prevalence rate of psychogenic polydipsia associated hyponatremia is estimated to be about 20% among chronic psychiatric patients.1 Hyponatremia itself after polydipsia causes a variety of neuropsychiatric symptoms such as headache, vomiting, lethargy, psychosis, and seizures.4 These symptoms can lead to life-threatening complications, including falls, attention deficits, osteoporosis, and fractures.5 The described patient’s manic state developed after escitalopram (a serotonin reuptake inhibitor, or SSRI) prescribed for 6 months. SSRIinduced manic switch could not be fully ruled out despite discontinuing escitalopram therapy for 1 week. SSRIs are sometimes the cause of hyponatremia and commonly have side effects of nausea and vomiting,4 a potent stimulus of vasopressin,4 which may further contribute to the development of hyponatremia. Here, the patient presenting hyponatremiaassociated panic symptoms masked underlying BAD and led to a delayed diagnosis and treatment. Both BAD and hyponatremia have been reported the important causes of cognitive deficits.4,6 Therefore, a routine measurement of sodium levels in chronic psychiatric patients would be needed because of the high prevalence rate and adverse consequences of hyponatremia mentioned above. The authors report no financial relationships with commercial interests.

J Neuropsychiatry Clin Neurosci 26:4, Fall 2014

Li-Fen Chen, M.D. Dept. of Psychiatry, Tri-Service General Hospital, Taipei, Taiwan School of Medicine, National Defense Medical Center, Taipei, Taiwan Hsin-Chang Chi, B.S.N. Dept. of Nursing, Taipei Tzuchi Hospital, The Buddhist Medical Foundation, Taipei, Taiwan School of Medicine, Tzu-Chi University, Hualien, Taiwan Ching-En Lin, M.D. Dept. of Psychiatry, Taipei Tzu Chi Hospital, The Buddhist Medical Foundation, Taipei, Taiwan School of Medicine, Tzu Chi University, Hualien, Taiwan Send correspondence to Dr. Lin; e-mail: [email protected] References 1. de Leon J, Verghese C, Tracy JI, et al: Polydipsia and water intoxication in psychiatric patients: a review of the epidemiological literature. Biol Psychiatry 1994; 35:408–419 2. Riggs AT, Dysken MW, Kim SW, et al: A review of disorders of water homeostasis in psychiatric patients. Psychosomatics 1991; 32:133–148 3. Duraiswamy K, Rao NP, Venkatasubramanian G, et al: Psychogenic polydipsia in bipolar affective disorder–a case report. Gen Hospital Psychiatry 2011; 33:84 e9-10. 4. Reddy P, Mooradian AD: Diagnosis and management of hyponatraemia in hospitalised patients. Int J Clin Pract 2009; 63:1494–1508 5. Kinsella S, Moran S, Sullivan MO, et al: Hyponatremia independent of osteoporosis is associated with fracture occurrence. Clin J Am Soc Nephrol 2010; 5:275–280 6. Chou YH, Wang SJ, Lirng JF, et al: Impaired cognition in bipolar I disorder: the roles of the serotonin transporter and brain-derived neurotrophic factor. J Affect Disord 2012; 143:131–137



Hyponatremia masquerading as panic symptoms in bipolar affective disorder.

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