Evaluation of Kidney Function in Bipolar Patients: A Cross-Sectional Study

Abstract

Bipolar disorder is a chronic disease that represents a significant problem to the affected individual. To date, the mainstay treatment for bipolar disorder consists in mood stabilizers, mainly lithium, which have been linked to acute and chronic kidney injury. To investigate the association between Estimated Glomerular Filtration Rate (eGFR) and sociodemographic and clinical characteristics in a group of patients with bipolar disorder (BD) undergoing lithium treatment, with or without concomitant use of other psychopharmaceuticals. In this cross-sectional study data was collected using the instruments: 1 – Clinical and sociodemographic data questionnaire, developed by the Brazilian Consortium for Bipolar Disorder Research; 2 – Structured Clinical Interview for the DSM-IV Axis I Disorders; 3 – Hamilton’s Rating Scale for Depression, to evaluate depressive symptoms and 4 – Young’s Rating Scale for Mania to evaluate mania symptoms. Renal function was calculated through the CKD/EPI formula for eGFR. 95 patients were included in the final analysis. 26 (27.4%) patients presented reduction in eGFR, 21 (22,1%) with eGFR between 60 to 89 and 5 (5,2%) below 60. Higher serum lithium levels and age were associated with such reduction (β = -18.06 [95% CI: -34.70 to -1.42]); (β = -0.72 (95% CI: -1.10 to -0.33)), respectively. Although lithium is considered the “gold standard” in the treatment of BD, its toxicity and tolerability profile in relation to renal function still needs to be better understood. The results of this study reinforce the idea that periodic control of lithium levels is essential for preserving renal function. Long-term longitudinal studies are needed to assess the relationship between renal function and lithium therapy in BD patients. Keywords Lithium, Bipolar Disorder, Kidney, Renal Insufficiency