Plasma concentrations of syndecan-1 are dependent on kidney function

Elevated plasma concentrations of syndecan-1 and heparan sulfate in studies of trauma, sepsis, and major surgery are commonly assumed to indicate acute glycocalyx degradation. We explored a possible role of the kidneys for these elevations.

Plasma and urine concentrations of syndecan-1, heparan sulfate, and biomarkers of inflammation were measured over 5 hours in 15 hospital patients treated for post-burn injury. The renal clearances of syndecan-1 and heparan sulfate (CL_R ) were calculated and their influence on the plasma concentration predicted by simulation.

The urine/plasma concentration ratio was 0.9 (0.3-3.0) for syndecan-1 and 2.8 (2.0-4.3) for heparan sulfate. The CL_R varied 250-fold for syndecan-1 and 10-fold for heparan sulfate. Multiple linear regression analysis showed that CL_R for syndecan-1 was positively associated with the creatinine clearance (P < .0032) and the urine flow (P < .015). CL_R for heparan sulfate increased with interleukin-6 (P < .003) and the urine flow (P < .01). Simulations suggested that a change in CL_R from the mean of the highest 3 to the lowest three values would double plasma syndecan-1 within 4 hours and cause a 7-fold rise after 24 hours. A similar change in CL_R for heparan sulfate would triple the plasma level within 24 hours, even if no increased shedding of the glycocalyx takes place.

The renal elimination of syndecan-1 and heparan sulfate varied greatly. A change in kidney function, which is common after trauma and major surgery, might alone induce several-fold changes in their plasma concentrations.