Objective: Lithium-induced natriuresis may lead to lithium retention and fluctuation of lithium levels during maintenance therapy. Therefore, the present study was conducted to evaluate the effect of add-on sodium chloride on serum lithium levels in bipolar disorder.
Methods: This RCT was conducted in 60 patients with type I bipolar disorder who were randomized into the control group that received lithium carbonate with the advice not to take additional salt (at the table) and the test group that received sachets of sodium chloride (1 g/d) as an add-on to lithium carbonate and were advised to restrict their additional salt intake (at the table) to 1 g/d. After baseline assessments, all patients were followed up at 4 weeks, 8 weeks, and 12 weeks when serum lithium, sodium, and potassium were estimated. Serum creatinine and aldosterone were repeated at 12 weeks. The percentage of patients showing fluctuations in serum lithium level (serum lithium <0.6 mEq/L or >0.8 mEq/L) was considered as the primary outcome measure.
Results: In the test group, the fluctuation rate in serum lithium (26.7%) was significantly (p = 0.01) lower than that in the control group (63.3%). Serum lithium values varied significantly across sampling times in the control group but not in the test group. There was a significant difference in serum lithium between the groups at 8 and 12 weeks of follow-up. There were no significant differences in the change in serum sodium, potassium, creatinine, aldosterone, creatinine clearance, and blood pressure within the group and between the groups. A significant positive correlation was found between serum lithium and aldosterone at baseline.
Conclusions: Intake of add-on sodium chloride (1 gm/day) may reduce the fluctuations in serum lithium during the maintenance phase of lithium therapy in type I bipolar disorder.
Gov identifier: NCT04222816.
Keywords: bipolar disorder; lithium; sodium chloride.
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