Researchers from the University of Washington looked at more than 2,700 people. None had high blood pressure, cardiovascular disease, or symptoms of kidney disease when the study began. But nearly 20 percent of the group eventually developed hypertension. Researchers found those people had higher levels of cystatin-c. That's a protein typically filtered out of the blood by the kidneys.
The researchers say these findings suggest kidney function influences the risk of hypertension. But they're unclear why.