High blood pressure is well known to be a major risk factor for heart disease. It's also a risk factor for kidney disease. High blood pressure causes damage to small blood vessels in the kidney and is a frequent cause of kidney damage and chronic kidney disease. Damage to the kidneys activates hormone pathways that result in increased fluid overload, which compounds high blood pressure and kidney damage.
Doctors perform a serum creatinine test on most patients with heart failure. The results of this test, which measures the amount of a chemical molecule called creatinine in the blood, tell doctors how well the patient's kidneys are functioning. If the levels are rising, it's a telltale sign that the kidneys are failing. Increased serum creatinine level is also a risk factor for heart disease.
Like the story about the chicken and the egg, it's sometimes hard to tell what came first when examining symptoms of kidney disease and heart disease. Both diseases have symptoms that can contribute to an increased risk of the other. For example, high blood pressure is a symptom of kidney disease -- and it's also a risk factor for heart disease. The same is true for abnormal blood levels of certain molecules, including electrolytes (like sodium) and fats (such as cholesterol and triglycerides).
On the other hand, severe high blood pressure, excess sodium and water in the blood (fluid overload) and a reduction in heart function are symptoms of heart failure that are also risk factors for kidney disease. We'll learn more about fluid overload on the next page.