By Julian Booker, MD
I have spent a great deal of time discussing medical conditions that directly affect your heart or are a consequence of heart disease. Today’s topic is not specifically a heart related condition but is directly related and pertinent nonetheless. The kidneys and the heart have a partnership in managing the cardiovascular system. In business terms the heart is like the chief executive officer (the BOSS,) and the kidneys are like the chief financial officers (really important but not quite as important as the CEO). Kidney doctors may argue the hierarchy but since this is my post I chose the ranking. The heart and kidneys work together to regulate blood pressure and the body’s fluid levels
Chronic kidney disease, or chronic kidney failure is a condition where your kidneys have been damaged and do not perform their primary functions at peak capacity. In addition to the aforementioned duties, the kidney’s most well-known function is to help filter the blood of various toxins and excess byproducts of metabolism.
Like other cardiovascular and related diseases such as hypertension, high cholesterol, heart failure and diabetes the onset can be insidious. Your kidneys may be failing for quite some time without you ever knowing. It is often only after developing profound kidney failure that you develop symptoms. Some symptoms to look for include:
- Decrease in daily urine production
- Leg or abdominal swelling
- Persistent itching
- Difficult to control blood pressure (hypertension)
- Shortness of breath or symptoms consistent with heart failure
- Weakness or fatigue
- Sharp chest pain that tends to be worse when lying flat compared to sitting forward
- Persistent loss of appetite
The good thing is that usually this is a progressive condition that can be detected by routine blood work. The blood urea nitrogen (BUN) and serum creatinine are our primary indicators of kidney function. From these values we can calculate a glomerular filtration rate (GFR). The GFR estimates how much blood your kidneys are able to purify in a given minute. GFR is the best metric to watch when following kidney function. Your health care professional will use the GFR to categorize your kidney disease
- Stage I: Your GFR is still normal (>90) but there is evidence in urine tests that there may be a problem
- Stage II: Your GFR is mildly decreased (60-90)
- Stage III: Your GFR is significantly reduced (30-60). We really need to be aggressive about controlling your risk factors.
- Stage IV: GFR is 15-30. At this point you have severely reduced kidney function. We need to start making preparations for dialysis as it is imminent.
- Stage V: GFR is less than15. You have very severe kidney dysfunction and dialysis will likely be initiated soon.
But why does this belong on a heart blog? First, we are medicine doctors and concern ourselves with the whole person. Second, the heart and kidneys are more related than simply sharing a job. The disease processes that affect one will also affect the other. The two main causes of chronic kidney failure are hypertension and diabetes which are also two of the leading causes of heart disease. Persons with chronic kidney disease have a much higher risk of cardiovascular events including heart attack, stroke, heart failure, peripheral artery disease and death than the general population.