d-mannosuria levels measured 1 h after d-mannose intake can select out favorable responders: A pilot study

d-mannose is used as preventive measure against recurrent urinary tract infections (RUTIs). We studied d-mannosuria after a challenge test to identify favorable responders that could be targeted for long-term preventive therapy.

Following institutional review board approval, women attending a specialized tertiary care center urology clinic with a history of RUTIs were invited to participate by providing a urine sample (baseline), followed by the intake of home-dose d-mannose, and a second urine sample 1 h later (post). Urine samples were processed according to a d-mannosuria assay technique reported previously by our group. d-mannose concentrations were normalized to urinary creatinine.

From July 2020 to March 2021, 26 patients met study criteria. Thirteen had a lower or unchanged ratio of baseline to post d-mannose, whereas 13 were responders. Among 19 taking 2 g, 12 had a lower or unchanged trend and 7 were responders with >20% increase in the d-mannose/creatinine ratio. Comparison of urinary baseline d-mannose/creatinine ratios was significantly different between the responder (mean = 0.337 ± 0.158) and nonresponder (mean = 0.692 ± 0.444; p = 0.016) groups. Urinary post d-mannose/creatinine ratios did not significantly differ between the two groups (p = 0.46). d-mannose-naïve patients had few responders, and age and urinary creatinine did not affect the findings.

This preliminary study on d-mannose challenge tests indicates a urine response if urinary d-mannose/creatinine ratio is low, which it was in some women with a history of RUTIs.