Lithium in the time of COVID: forever vigilant.

Background: There have been case reports of renal dysfunction with lithium toxicity among severely ill COVID-19 patients. Lithium levels may be affected by comorbid conditions and the presence of infective disease states like the SARS-CoV-2 which clearly adds systemic health burden. This study aimed to review the effect SARS-CoV-2 has on serum Li levels and the possible mechanism underlying it.

Methods: Retrospective data from all clinical service encounters within the University of Michigan health system between September 2019 and September 2023 were reviewed. The study cohort included 98 patients with an average age of 45 years (62% female) who were diagnosed with any subtype of bipolar disorder, actively taking Li, and infected with SARS-CoV-2 during the study timeframe.

Results: There was no overarching effect of a SARS-CoV-2 infection on Li chemistry in the overall sample. Higher serum Li levels were not significantly associated with SARS-CoV-2 infection nor total comorbidity index. However, higher Li levels were observed in males while infected with SARS-CoV-2 when compared with no infection. eGFR remained unassociated with serum Li level. Receiving COVID vaccination was associated with lower serum Li levels (Coeff. = - 0.88, p = 0.048).

Conclusions: Patients with a diagnosis of BD, treated with Li, and infected with SARS-CoV-2 were not likely to present with elevated Li levels unless they are male or unvaccinated. Elevated serum Li level was not associated with significant renal dysfunction in this cohort. The case reports of severe renal complications and Li toxicity may be among cases of greater overall clinical severity of COVID-19. These findings are reassuring that Li may be used in the context of a COVID-19 illness but emphasize the ongoing need for clinical vigilance.