Cystatin C, kidney function, and cardiovascular risk factors in primary hypertension

Objective

To investigate the clinical usefulness of serum cystatin C (Scys) and cystatin C-based equations for the screening of chronic kidney disease in primary hypertensive patients, and correlate these markers with risk factors for cardiovascular disease.

Methods

A cross-sectional study was performed in 199 middle-aged adults at a basic health unit. Kidney function assessment included measurements of serum creatinine (Scr) and Scys levels, 24-hour microalbuminuria (MA), as well as glomerular filtration rate (GFR) through Larsson and Modification of Diet in Renal Disease (MDRD) study equations. Bland-Altman plot analysis was used to calculate the agreement between equations.

Results

High levels of Scys were found in 22% of the patients, even with normal values of GFR estimated by MDRD study equation. Systolic blood pressure and MA correlated better with Scys than Scr, but there was no correlation between Scys and diastolic blood pressure. Gender, age ≥ 60 years, MA, and uric acid were significantly associated with high Scys levels. After multivariate analysis, only age ≥ 60 yrs (RR = 6.4; p < 0.001) and male gender (RR = 3.0; p = 0.006) remained associated with high Scys levels.

Conclusion

Cystatin C can be used as a screening marker both for detecting mild declines of renal function and for preventing the risk of cardiovascular events in hypertensive subjects with presumably normal renal function.