To the Editor:
We read with interest the paper by Flythe et al.1 that examines the efficacy, safety, and tolerability of oral furosemide in patients undergoing hemodialysis. We congratulate the authors for conducting this useful and long-needed study that consisted of a 6-week dose titration period and a 12-week follow-up period. The maximum furosemide dose for any participant was 320 mg/d. Flythe et al.1 conclude that furosemide was generally safe and well tolerated.
In this regard, we would like to share information about our practice2,3 using higher doses and for a longer time. Initially, it was needed to establish a maximal effective dose for incident patients. To this end, we conducted a crossover, single-blind study. Thirty-four patients were randomly assigned to receive 250 mg or 500 mg of oral furosemide once a day for 1 week. Effect of both doses on urine output was similar. Both increased 24-hour urinary volume by 30%. In contrast, sodium excretion was significantly higher with 500 mg. Subsequently, daily urine output was measured in all incident patients. The patients with daily urine output higher than 200 ml a day received 500 mg of oral furosemide once a day. After 11.8 ± 4.7 months, 33 incident patients were able to preserve their baseline residual urine output and their excretion of sodium and phosphorus. Serum β2-microglobulin was significantly lower than β2-microglobulin measured in control patients. There were no significant changes in serum levels of potassium and calcium. Only 4 patients experienced adverse events. One experienced cramps and 4 experienced rash and pruritus. All symptoms improved when furosemide was discontinued. No patient reported changes in their hearing.
These preliminary results2,3 support the conclusions of Flythe et al.1; high doses of furosemide are effective, safe, and well tolerated in patients undergoing hemodialysis. Furthermore, well-designed randomized controlled trials are needed to verify these findings.
References
- 1.Flythe J.E., Assimon M.M., Tugman M.J., et al. Efficacy, safety, and tolerability of oral furosemide among patients receiving hemodialysis: a pilot study. Kidney Int Rep. 2022;7:2186–2195. doi: 10.1016/j.ekir.2022.07.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Alcuaz R., Nozzi E., Vivas N., Diaz G., Aiziczon D., Siga E. The preservation of residual renal function with high dose of furosemide. A pilot long-term study. Nephrol Dial Transplant. 2019;34(suppl 1) doi: 10.1093/ndt/gfz106.FP683. gfz106.FP683. [DOI] [Google Scholar]
- 3.Siga E., Alcuaz R., Nozzi E., et al. Survival and residual kidney function in hemodialysis patients treated with high doses of furosemide. A prospective long-term study. Nephrol Dial Transplant. 2020;1755(suppl 3) doi: 10.1093/ndt/gfaa1. gfaa142.P1441. [DOI] [Google Scholar]