Are there any special risks associated with lithium treatment in cystic fibrosis patients?

Fråga: Are there any special risks associated with lithium treatment in cystic fibrosis patients?

Sammanfattning: Reduced renal excretion of lithium in cystic fibrosis patients has been observed in one study. Careful therapeutic drug monitoring of lithium should be practiced in this group of patients.

Svar: Cystic fibrosis is an autosomal recessive disorder of defective chloride transport caused by a mutation on chromosome 7 (1). Treating cystic fibrosis patients with lithium for mania has caused some concern due to the similarity with the handling of sodium and lithium.

One study that directly looked at the body´s handling of lithium concluded that there was a difference in lithium levels in eight cystic fibrosis patients that were tested after being given 600 mg of lithium (2). Not only did these patients have higher serum levels, they also had lower fractional renal excretion of lithium.

In contrast, there is a case report of a 30-year-old manic female with cystic fibrosis that was started on lithium therapy. No adverse effects have been seen, there was no impact on her cystic fibrosis, and lithium levels remained within an expected level (1). She was taking 450 mg twice daily. 1 Beckwitt Turkel S, Cafaro DR: Lithium treatment of a bipolar patient with cystic fibrosis. Am J Psychiatry 1992; 149: 574 2 Brager NPD, Campbell NRC, Reisch H, Chaudhuri M, Rabin HR: Reduced renal fractional excretion of lithium in cystic fibrosis. Br J Clin Pharmacol 1996; 41: 157-159