Kidney disease can speed up the development of heart disease and vice versa, according to findings from two studies involving more than 50,000 patients. Long before kidney disease has ravaged the kidneys, something triggers and accelerates heart disease. In fact, most patients with chronic kidney disease die of heart disease long before they need dialysis.

In one study, researchers followed up on 37,000 people (average age, 53) who'd volunteered for kidney screening and analyzed three markers of kidney function in each volunteer: the estimated glomerular filtration rate, levels of the protein albumin in urine (microalbuminuria), and markers for anemia. As each of the markers worsened, so did the odds of having heart disease. Study participants who had both chronic kidney disease and heart disease had a threefold higher risk of death, mostly from heart problems, in the 21/2-year study period.

Another study involved more than 13,000 people who were part of two large heart-health studies. Researchers found that those with heart disease at the start of the study had twice the risk of experiencing declining kidney function during the following 9 years.

Although researchers haven't pinned down the relationship between the two conditions, they say the link goes far beyond their shared risk factors of high blood pressure and diabetes. They call for better early detection and care of kidney disease and advise health care providers who care for patients with cardiac disorders to carefully monitor kidney function too.

Sources: McCullough PA, et al., Independent components of chronic kidney disease as a cardiovascular risk state, Archives of Internal Medicine, June 11, 2007; Elsayed EF, et al., Cardiovascular disease and subsequent kidney disease, Archives of Internal Medicine, June 11, 2007.