title: Risk factors for polyuria in a cross-section of community psychiatric lithium-treated patients.
abstract: OBJECTIVE
  Polyuria increases the risk of dehydration and lithium toxicity in lithium-treated patients. Risk factors have been inconsistently described and the variance of this adverse effect remains poorly understood. This study aimed to establish independent risk factors for polyuria in a community, secondary-level lithium-treated sample of patients.
  
  
  METHODS
  This was a cross-sectional study of the lithium-treated patients attending a general adult and an old age psychiatry service. Participants completed a 24-hour urine collection. Urine volume and the presence of polyuria were the outcomes of interest. The relationship between outcome and the participant's demographic and clinical characteristics was explored with univariable and multivariable analysis.
  
  
  RESULTS
  A total of 122 participants were included in the analysis, with 38% being diagnosed with polyuria. Female gender and increased body weight independently predicted the presence of polyuria (standardized regression coefficient 1.01 and 0.94, respectively; p = 0.002 and p = 0.003, respectively). Female gender and increased body weight, lithium dose, and duration of lithium treatment independently predicted higher 24-hour urine volumes (standardized regression coefficients 0.693, p < 0.0005; 0.791, p < 0.0005; 0.276, p = 0.043; 0.181, p = 0.034, respectively). Of three different weight metrics, lean body weight was the most predictive.
  
  
  CONCLUSIONS
  Female gender and increased body weight explain part of the variance of this adverse effect. Both risk factors offer fresh insights into the pathophysiology of this potentially reversible and dangerous adverse effect of lithium treatment. Future research should focus on understanding the differences between the genders and between different body compositions in terms of lithium pharmacokinetics and pharmacodynamics.
authors: UCD School of Medicine and Medical Science, Department of Adult Psychiatry, University College Dublin, Mater Misericordiae University Hospital, Dublin, Ireland.
authors: James Conor
authors: JC
authors: Kinahan
authors: Aoife
authors: A
authors: NiChorcorain
authors: Sean
authors: S
authors: Cunningham
authors: Aideen
authors: A
authors: Freyne
authors: Colm
authors: C
authors: Cooney
authors: Siobhan
authors: S
authors: Barry
authors: Brendan D
authors: BD
authors: Kelly
mesh_terms: D000328:Adult; D000368:Aged; D018692:Antimanic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D001682:Biological Availability; D001714:Bipolar Disorder / Q000188:drug therapy*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007494:Ireland / Q000453:epidemiology; D018020:Lithium Compounds / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D011141:Polyuria / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D018692:Antimanic Agents; D018020:Lithium Compounds
keywords: bipolar disorder; body weight; lithium; nephrogenic diabetes insipidus; polyuria; risk factor