Measuring and estimating daily urine volume in psychiatric patients: strengths and weaknesses

Development of diagnostic criteria and severity scale for polydipsia: A systematic literature review and well-experienced clinicians' consensus

Despite the clinical importance of polydipsia, no diagnostic criteria or severity scales that comprehensively assess this condition are available. Thus, we aimed to develop diagnostic criteria and a severity scale for polydipsia based on a systematic review and well-experienced clinicians' consensus. We performed a systematic review, identified 27 studies related to diagnostic criteria or severity classification for polydipsia, and extracted items used to assess polydipsia in these studies. Ten well-experienced clinicians-5 psychiatrists and 5 nurses-participated in the Delphi method. They evaluated 39 items extracted based on the results of the systematic review regarding (1) their necessity in diagnosing and assessing the severity of polydipsia, and (2) their relative importance rated on 7-point scale among the items included in the severity scale. The Polydipsia Diagnostic Criteria (PDC) included 4 essential items-excessive drinking, low serum sodium level or low serum osmolality, abnormal normalized diurnal weight gain, and low urine specific gravity-based on consensus reached using the Delphi method. The Polydipsia Severity Scale (PSS) included 13 items with a maximum score of 59. The first diagnostic criteria and symptom scale for polydipsia were developed based on the findings of a systematic review and well-experienced clinicians' consensus.

Hiponatremia in the practice of a psychiatrist. Part 2: psychogenic polydipsia

Objective. The study is the second part of the literature review on hyponatremia in patients with diagnosed mental disorders. This article focuses on psychogenic polydipsia as, along with the SIADH, one of the two most common causes of hyponatremia in the mentioned group of patients.

Method: The literature review was based on searching the Medline, the Google Scholar and the Ebsco databases in Polish and English by entering the following phrases: psychogenic polydipsia, the psychosis – intermittent hyponatremia – polydipsia syndrome, water intoxication.

Discussion: Psychogenic polydipsia occurs in up to 25% of patients treated for mental disorders. It most frequently concerns patients with schizophrenia. 30% of patients with psychogenic polydipsia suffer from hyponatremia with or without symptoms of water intoxication. In the etiology of psychogenic polydipsia, the influence of dopaminergic and noradrenergic neurotransmission has been considered, as well as angiotensin, which is claimed to have dipsogenic properties. In order to reduce the severity of the disorder, attempts have been made to administer the following groups of medications: β-blockers, opioid receptor antagonists, angiotensin convertase inhibitors and angiotensin receptor antagonists. Other methods include replacing classic antipsychotic drugs with clozapine. There are also reports of a reduced severity of polydipsia with hyponatremia after introducing risperidone and olanzapine. Preventing episodes of water intoxication in patients with psychogenic polydipsia requires the monitoring of their body weight and a suitable reduction of fluid intake by them.

Results: Mentally ill patients, especially those with chronic schizophrenia, should be monitored for psychogenic polydipsia and the concomitant hyponatremia.

Brain circuit dysfunction in a distinct subset of chronic psychotic patients

OBJECTIVE

To identify the mechanism of unexplained hyponatremia and primary polydipsia in schizophrenia and its relationship to the underlying psychiatric illness.

METHODS

Briefly review previous studies that led to the conclusion the hyponatremia reflects altered hippocampal inhibition of peripheral neuroendocrine secretion. In greater detail, present the evidence supporting the hypothesis that circuit dysfunction associated with the hyponatremia and the polydipsia contributes to the underlying mental disorder.

RESULTS

Polydipsic patients with and without hyponatremia exhibit enhanced neuroendocrine responses to psychological stress in proportion to structural deformations on their anterior hippocampus, amygdala and anterior hypothalamus. Nonpolydipsic patients exhibit blunted responses and deformations on other hippocampal and amygdala surfaces. The deformations in polydipsic patients are also proportional to diminished peripheral oxytocin levels and impaired facial affect recognition that is reversed by intranasal oxytocin. The anterior hippocampus is at the hub of a circuit that modulates neuroendocrine and other responses to psychological stress and is implicated in schizophrenia. Preliminary data indicate that other measures of stress reactivity are also enhanced in polydipsics and that the functional connectivity of the hippocampus with the other structures in this circuitry differs in schizophrenia patients with and without polydipsia.

CONCLUSION

Polydipsia may identify a subset of schizophrenia patients whose enhanced stress reactivity contributes to their mental illness. Stress reactivity may be a symptom dimension of chronic psychosis that arises from circuit dysfunction that can be modeled in animals. Hence polydipsia could be a biomarker that helps to clarify the pathophysiology and heterogeneity of psychosis as well as identify novel therapies. Clinical investigators should consider obtaining indices of water balance, as these may help them unravel and more concisely interpret their findings. Basic researchers should assess if the polydipsic subset is a patient group particularly suitable to test hypotheses arising from their translational studies.

The assessment and treatment of water imbalance in patients with psychosis

Polydipsia and episodic life-threatening water intoxication remain important clinical problems for a significant portion of persons with schizophrenia. The disorders are associated with increased morbidity and mortality from a number of causes. With a basic understanding of the pathophysiology, one can easily diagnose and assess the clinical conditions. We review here the scope and pathophysiology of disordered water imbalance, including both primary and secondary polydipsia and hyponatremia. Reversible factors and possible interventions are reviewed. Treatment options for preventing water intoxication have expanded from discontinuation of offending agents, targeted fluid restriction, and clozapine therapy to the addition of oral vasopressin antagonists. The latter, however, are extremely potent and must be carefully monitored.