German Journal of Psychiatry
E. Mercier-Guidez1, A. Verrier1 and A. Smail2
1University Department of Psychiatry, CHU Nord, 80000 Amiens, France
2University Department of Internal Medicine, CHU Nord, 80000 Amiens, France
Corresponding author: E. Mercier-Guidez, University Department of Psychiatry, CHU Nord, 80000 Amiens
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Key words : psychogenic polydipsia, polydipsia, water intoxication, hyponatraemic encephalopathy, schizophrenia
A 42-year-old man presented an acute episode of psychogenic polydipsia lasting 5 days in which he drank up to 6 l of fluids daily. The episode was observed 24 hours after his admission to a general hospital for asthenia. This patient, who did not have a history of physical or mental disease, managed a plantation of tropical plants.
During this episode of polydipsia, the patient presented headache, weakness, and diarrhoea. No signs of severe water intoxication (confusion, delirium, seizures or coma) were seen during this period of observation. Blood pressure was 120/70 mmHg, sinus rhythm 84 beats/min, and temperature 37.5°C. Laboratory results: haemoglobin 9.56 mmol/l (normal 8.2-11.0 mmol/l), haematocrit 44.9% (42-52%), leukocytes 10.6 109/l, sedimentation rate 5 mm, C-reactive protein < 5, and serum sodium measured at the end of the afternoon 136 mmol/l (normal 135-145 mmol/l). Potassium, calcium, urea, creatinine, and blood glucose were normal. Serum osmolarity was 280 mOsm/kg (normal 285-295 mOsm/kg). Urine osmolarity was low (67 mOsm/kg), urine sodium was 22 mmol/l and urine specific gravity was decreased to 1001.
To evaluate the water balance of the patient, two diurnal weight measurements (in the morning and in the afternoon) were made during five consecutive days. No diurnal body weight gain was found. The water-restriction test indicated primary polydipsia. Cerebral magnetic resonance imaging was normal.
At the end of the investigations, all possible organic factors were excluded. We concluded that this was an episode of psychogenic polydipsia, without water intoxication or sub-intoxication. The patient also fulfilled the DSM-IV criteria for Major Depressive Disorder (DSM-IV 296.22) with symptoms of depressive mood, lack of interest, asthenia, inability to concentrate, guilt feelings, repetitive suicidal thoughts and also social and professional dysfunction. This depressive disorder was stress-related due to overwork. All the symptoms of polydipsia regressed after a brief period of strict fluid restriction, an anxiety-relieving treatment by slow intravenous administration of benzodiazepines and supportive psychotherapy. The patient explained that he felt better after drinking water. To his mind, water was synonymous with life and when his tropical plants were withering, it was necessary to give them water. Except for this borderline confusion between himself and his tropical plants, the rest of his conversation did not contain delirium or psychotic symptoms. The patient was therefore discharged from hospital. Three months after the beginning of antidepressant treatment, the symptoms of depression disappeared. During this period of observation, we also reported symptoms such as fear of abandonment, unstable interpersonal relationships, identity disturbance, affective instability with irritability and anxiety. It was concluded that this patient presented a Borderline Personality Disorder (DSM-IV 301.83). No recurrent episodes of psychogenic polydipsia was observed over a one-year follow-up period.
When an acute episode of polydipsia (more than 3 litres of water per day) is investigated, an underlying water intoxication (which sometimes leads patients to medical intensive care units (E. Mercier-Guidez, 1998) should first be eliminated. It is clear from the literature, that only a subgroup of patients with psychogenic polydipsia runs a risk of water intoxication. The clinical signs of water intoxication are essentially those of hyponatraemic encephalopathy: headache, weakness, nausea, vomiting, diarrhoea, confusion, seizures, coma, and even death (Illowski and Kirch, 1988). Moreover, the increased intake of fluids throughout the day and the accompanying water retention lead to significant weight gain and concurrent hyponatraemia in the afternoon (De Leon and al., 1994; Vieweg and al., 1994). In the patient we described, these two parameters were normal. Thus, we concluded that the clinical signs of headache, weakness, and diarrhoea presented by this patient during the episode of polydipsia were not related to water sub-intoxication as we first thought. Stress state was considered the most likely explanation.
Most epidemiological surveys performed in long-term psychiatric hospitals have shown that psychogenic polydipsia occurs frequently among chronic psychiatric patients, particularly those with schizophrenia. Other psychiatric diagnoses have also been associated with polydipsia, such as affective disorders, psychosis with onset during childhood, mental retardation and personality disorders (De Leon and al., 1994; Illowski and Kirch, 1988). In fact, psychogenic polydipsia has essentially been studied in psychiatric inpatients. The present case suggests that psychogenic polydipsia does not occur solely in chronic psychiatric inpatients. Outpatients may also be involved. It is hoped that this observation will help clinicians to better identify psychogenic polydipsic patients at risk of water intoxication and will promote future studies in non-psychiatric populations.
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