The aim of this cross-sectional descriptive research was to study prevalence rates, odds ratio of lithium induced nephrotoxicity and correlation of lithium level and nephrotoxicities in psychiatric patients at psychiatric out-patient department at Phramongkutklao Hospital from October 2000 to April 2001. Forty two psychiatric lithium users and thirty five psychiatric non-lithium users were recruited to this study. The prevalence rate of nephrotoxicities in psychiatric lithium users were polyuria 39.39, decrease urine concentrating ability 85.70, proteinuria 88.10 and nephrogenic diabetes insipidus 27.27, respectively. Strength of association between lithium-used and nephrotoxicities by odds ratio were polyuria 2.13 (95% CI, OR = 6.40-0.70), decrease urine concentrating ability 1.24 (4.25-0.36), proteinuria 2.13 (7.43-0.64) and nephrogenic diabetes insipidus 2.19 (4.69-0.44). The correlation between lithium level and nephrotoxicities showed negative statistical significant (p=0.031) in lithium level and urine osmolality at correlation coefficient of -0.346 but showed positive statistical significant (p=0.018) in duration of lithium-used and serum creatinine at correlation coefficient of 0.362. In addition, trend of lithium induced nephrotoxicity were presented in more than 10 years of lithium-used. Lithium half life which calculated from 24 hrs urine creatinine clearnance and lithium level showed linear relationship with duration of lithium-used. Lithium induced nephrotoxicities correlated with duration of lithium-used and lithium level. So, renal function and lithium level should be monitor to provent nephrotoxicity in long term lithium-users.
