Malnutrition and Sarcopenia: A Common Comorbidity
JUNE 10, 2016
MD Magazine Staff
Peter A. McCullough, MD: Malnutrition is common. In fact, it can affect up to 50% of patients in the broad populations of patients with chronic cardiovascular disease, largely heart failure, and chronic cancers that are being treated currently in the United States. For those populations, there’s about 6 million heart failure patients, and there’s about 24 million cancer survivors or patients undergoing treatment right now. And, then, two smaller groups, one with chronic autoimmune disease—and autoimmune can involve a whole spectrum including rheumatoid arthritis, psoriatic arthritis, Crohn’s disease, ulcerative colitis, and various skin conditions like psoriasis. And, then, the last is neurodegenerative disease, and our listeners will recognize Alzheimer’s disease, multiple sclerosis, forms of stroke, cerebral palsy, and Parkinson’s disease. This is kind of a broad grouping of diseases. All of these can have malnutrition become a problem; in fact, become a dominant condition or comorbidity that influences treatment outcomes.
In my practice on the inpatient service, I would estimate that probably about 30% of patients broadly—maybe up to 50% of those with heart failure—do have evidence of cardiac cachexia or sarcopenia. They may have excess body fat and that’s common. So, it’s important on physical examination to get a sense of the size and the mass of the large muscle groups, including the deltoids, the gluteus, and the quadriceps. And one can, I think, relatively quickly understand if there is reduced muscle mass. If muscle mass gets reduced enough, there will be generalized weakness, and a great test for patients is to have them sit on the floor and see if they can actually get up off the floor on their own. And you’ll be amazed how many elderly patients are completely stuck. They don’t have enough strength to get up off the floor.
It’s important to realize that muscle loss occurs because the body has a strength or has a demand for the basic building blocks of protein called amino acids. So, the body will break down muscle and sacrifice muscle to provide amino acids to other organs in the body, including bones and particularly the liver. The skeletal muscles are a reservoir of protein; and that protein is broken down through very common catabolic functions in the human body. It’s called proteases, and they do break down polypeptides into amino acids. And those amino acids are used elsewhere. So, if we are not supplementing the body with essential amino acids, protein, and other key substances, we don’t maintain muscle mass. In fact, we lose it in the setting of chronic disease. And once lost, it becomes difficult to build back, almost impossible to build back with food diets alone.