Australian and New Zealand Journal of Mental Health Nursing (2000) 9, 177–183 INTRODUCTION Abnormalities of water balance in psychiatric patients have been recognized since the early part of this century (Barahal, 1938). From the 1930s to the 1950s, the focus was primarily on the epidemiology of the syndrome variously described as compulsive water drinking, self- induced water intoxication, disordered water balance, psychogenic polydipsia or the PIP syndrome (for psychosis, intermittent hypona- traemia and polydipsia). Subsequently, attention turned to exploring pharmacotherapeutic means of treatment and most recently to describing fully the physiological, biochemical and hormonal abnormalities associated with the presenting clinical picture (Goldman, 1991). The true incidence of the condition is un- certain, not least because of difficulties associ- ated with its detection (Tracy et al., 1997). F EATURE A RTICLE Identification and monitoring of disordered water balance: Bioelectrical impedance analysis as an alternative to the target weight procedure Correspondence: Dr L C Ward, Department of Bio- chemistry, University of Queensland, Brisbane, Qld 4072, Australia. Email: Ward@florey.biosci.uq.edu.au Ian Colls, MBBS, FRANZCP Ari Rees, BSc Leigh C. Ward, BSc, PhD Accepted December 1999. Ian Colls, 1 Ari Rees 2 and Leigh C. Ward 2 1 Wolston Park Hospital, Brisbane and 2 Department of Biochemistry, University of Queensland, Brisbane, Australia ABSTRACT: Many psychiatric patients present with disorders of water balance manifested by polydipsia or polyuria. Multiple frequency bioelectrical impedance analysis (MFBIA) was investigated as a suitable method for the assessment of body water in such patients. Whole body bioelectrical impedance, total body water and extracellular water and serum sodium were measured in 10 chronic psychiatric in- patients with polydipsia. Fluid volumes predicted by MFBIA correlated significantly (P < 0.002) with those obtained by reference methods but the relatively high limits of agreement (2.2 L) suggest that the method is not yet sufficiently accurate for random screening purposes. However, owing to the simplicity and non-invasive nature of the technique, it warrants further investigation and development, partic- ularly for routine patient monitoring. KEY WORDS: multiple frequency bioelectrical impedance analysis, polydipsia, total body water.