LITHIUM IN AFFECTIVE DISORDER AND GFR function i.e. serum creatinine, s1Chromium ethylene diamine tetra-acetic acid (51Cr-EDTA) clearance and serum fl2-microglobulin in lithium treated patients demonstrated a significant impairment when compared with affective disorder (AD) patients not receiving the drug. Tyrer et al. (1983) also reported deterioration of glomerular filtration rate (GFR) with long-term lithium therapy. Further, Jensen and Rickers (1984) reported that after lithium therapy, a significant proportion of patients (10/13) had lower GFR when measured 2 years after lithium treatment. However, there had been a considerable lack of information on the chronic effect of lithium treatment on renal functions in Indian population. In view of this, the present cross sectional study was carried out with an ethnic prespective and the long term effect of lithium treatment on GFR was evaluated in AD patients. MATERIAL AND METHOD Study subjects and treatment: Thirty AD patients receiving lithium as lithium carbonate were enrolled for the present study. Thirty age matched healthy subjects who were prospective kidney donors and who had never received lithium or any other drug on a chronic basis that could affect renal functions were included as a control group. An informed written consent was obtained from all the subjects participating in the study. All the patients met DSM-III-R criteria for AD (APA.1987). These patients had previously received or were receiving medications other than lithium (viz. antipsychotics, antidepressants, anticholinergics and sedative hypnotic;. The patients' demographic details and the treatment schedule are presented in table-1. GFR evaluation : GFR was estimated using the plasma clearance method. An intravenous injection of approximately 20 MBq of ""Technetium diethylene triamine pentaacetic acid (99mTc-DTPA) was given to each study subject and a known quantity of radiotracer was kept as standard. Subsequently, two milliliters of venous blood was withdrawn from each patient at 60, 90, 120, 150 and 180 minutes by using disposable and heparinized needles and syringes. Heparinized blood samples were allowed to stand for 3-4h and plasma was separated. Radioactivity in the plasma samples, standard sample and wash solutions (0.5 ml each) was countered by using a well type gamma counter (Nuclear Enterprises, Edinburg, U.K.) The left over activity in the needles and syringes were also accounted for the -purpose of calculating the total activity in the wash solution. Absolute GFR was estimated by single compartment, multiple plasma clearance method and expressed in ml/min which was then normalized for weight and height of the patient and expressed as ml/min/1.73 m2 (Russel et al.,1985). Estimation of serum Li levels : Serum Li levels were estimated by the flame photometry (Brown &Legg,1970). Statistics : Normality test, correlation analysis and student's 't' test were performed and the results were considered statistically significant when p value was < 0.05. For the test group, the values for various parameters were skewed whereas they were normal (non-skewed) for the control group. RESULTS Normality test revealed that dose and treatment duration were skewed and the coefficient of skewness were 0.067 (p<0 0001) and 1.41 (p<0.0001) respectively. Age was marginally skewed (p=0.04) for the control group. At 5% significance level, dose and creatinine were negatively correlated (r = -0.030), whereas age and duration were positively correlated (r = +0.53) (single tailed only) Duration and GFR seems to be negatively correlated (r = -0.23), however did not reach the significant level. The mean serum Li levels in the lithium treated AD patients were 0.72+0 19 mEq/L (range 0.42-1.19 mEq/L) and were in the therapeutic range. The mean GFR in AD patients undergoing lithium treatment and in the control group has 411