Elevations in serum lithium levels postcystectomy and ileal conduit

A female patient in her 60s with bipolar disorder type 1 underwent robot-assisted radical cystectomy with ileal conduit for muscle-invasive bladder cancer. Postoperatively, she continued her regular lithium dose of 600 mg nightly. By postoperative day 4, her lithium level had risen unexpectedly to 1.38 mmol/L, necessitating temporary discontinuation. Lithium was restarted on postoperative day 12 at 300 mg nightly (50% dose reduction), achieving therapeutic levels (0.63 mmol/L) within 3 weeks. She remained psychiatrically and medically stable during 3 months of follow-up. We propose that lithium reabsorption through the absorptive intestinal mucosa of the ileal conduit contributed to the elevated lithium levels and need for dose reduction. Currently, limited guidance exists from urological and psychiatric associations regarding pharmacokinetic interactions in patients with urinary diversion taking lithium. Based on this case, we recommend: increased lithium monitoring in the postoperative period, consideration of prophylactic dose reduction in the acute postoperative period and close psychiatric follow-up for safe re-titration.