Almost 15% of Americans have chronic kidney disease (CKD), with an even higher rate in Veterans due to common risk factors such as high blood pressure and diabetes. People with CKD have a high risk of cardiovascular (CV) diseases, such as heart attacks, heart failure, and strokes. Extra fluid in the body, called volume overload, may lead to CV disease in people with CKD. It is unknown if volume overload develops in the earliest stages of CKD, when treating it with common, inexpensive medicines called diuretics may improve long-term CV outcomes. This study will lay important groundwork to answer this question in Veterans with early CKD by comparing two ways to measure volume overload and studying the change in common symptoms like fatigue and short-term CV function after treatment with diuretic medicines.