Mannitol reliable Alternative Clearance Marker in CKD, suggests research

A new study published in the journal of Clinical Physiology and Functional Imaging showed that Mannitol demonstrated reliable performance as a clearance marker in patients with chronic kidney disease (CKD) stages 3–4 and may be considered a useful alternative when standard markers such as iohexol or isotopes. However, larger studies are needed to validate its clinical utility.

This research evaluated mannitol as a clearance marker for determining glomerular filtration rate (GFR). Traditionally, GFR is measured using markers such as iohexol or radioactive isotopes, which may not always be suitable for all patients due to contraindications or limited availability. This study explored whether mannitol could offer a simpler and equally accurate option.

The trial involved 20 outpatients diagnosed with stage 3–4 CKD. Each participant received simultaneous bolus injections of both mannitol and iohexol, the latter serving as the reference standard. Blood samples were collected at 3, 5, and 22 hours after injection, and analyzed using advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS). This research then applied the Bröchner–Mortensen multi-sample model to calculate GFR for both substances.

When comparing multi-sample clearance methods, mannitol demonstrated a very small average bias of just 0.95 mL/min/1.73 m² relative to iohexol, with an error rate of 10%. Also, accuracy reached 100% within both P30 and P10 thresholds which indicated how closely the results align with the reference method. This level of agreement suggests that mannitol performs nearly identically to iohexol under multi-sample conditions.

The study also assessed a simplified approach using a one-sample method based on the Jacobsson equation, which was applied to blood samples taken at 5 and 22 hours. Despite being less precise, the accuracy remained high, with up to 100% within P30 and 80% within P10 at certain time points, though variability and error rates were higher when compared to the multi-sample method.

Overall, the findings indicate that mannitol is a dependable marker for GFR measurement in patients with CKD stages 3–4, particularly when using a multi-sample approach. Its performance closely mirrors that of iohexol, which makes it a potential alternative in clinical situations where these markers cannot be used. Larger-scale investigations are required to confirm the reliability of mannitol across broader patient populations and clinical settings.

Source:

Kiss, K., Saeed, A., Ricksten, S.-E., & Bragadottir, G. (2026). Clearance of mannitol for assessment of glomerular filtration rate in chronic kidney disease: A validation against iohexol clearance. Clinical Physiology and Functional Imaging, 46(3), e70059. https://doi.org/10.1111/cpf.70059