Approximately 20 million people in the United States have some form of kidney failure. People with kidney failure have an increased chance of having low levels of high density lipid (HDL), so called "good cholesterol." Patients who are overweight or obese also have low levels of HDL. The investigators are trying to find out whether causes of low HDL are the same in people who are overweight and in patients with kidney failure so that in the future doctors can better treat low HDL cholesterol levels. People with low levels of HDL are more likely to have heart attacks and strokes and are more likely to lose kidney function. This study hope to learn more about how kidney failure causes low HDL cholesterol levels.