Sevelamer (S.), a calcium free phosphate binder, is also known for its ability to reduce serum cholesterol due to its binding affinity for bile acids. The aim of this study was to evaluate if the use of S. is associated with reduced serum levels of fat-soluble Vitamins (D and K) in patients with end stage renal disease (ESRD).
In a cross-sectional study of 387 hemodialysis patients (42.1% on S. treatment) from 18 dialysis centers, we determined serum concentrations of: 25(OH)-vitamin D and several vitamers of the vitamin K complex (vitK1, and vitamin K2 vitamers or menaquinones: MK4, MK5, MK6 and MK7) by high-performance liquid chromatography (HPLC). In addition, routine biochemistry and vitamin K related proteins (osteocalcin, or bone Gla Protein – BGP and matrix Gla protein - MGP), were also determined.
Patients treated with S, compared with non-treated patients, we observed no significant differences in serum levels of 25(OH)-vitamin D and of most vitamin K vitamers: vitamin K1, MK5, MK6, MK7. However, more S. treated patients had MK4 deficiency (13.5% vs. 5.4%, p=0.0052). Further, in S. treated patients we found higher levels of alkaline phosphatase (median, 89 vs. 77.5 U/L, p=0.0002), total BGP (median, 210 vs. 152 mcg/L, p=0.0022) and lower levels of total MGP (median, 16.4 vs 20.3 nmol/L, p= 0.0368).
We confirm in humans (dialysis patients on long-term S. treatment), that S. may interfere with vitamin K metabolism, based on an association with reduced MK4 levels and with different serum levels of vitamin K related proteins. These findings suggest that further studies are needed to confirm this association and determine if vitamin K2 supplementation is indicated in S. treated ESRD patients.