In the 1980s, physicians described a collection of physiologic traits that appeared to increase the risk for heart disease in some patients. These traits, called syndrome X, included abdominal obesity, high blood pressure, abnormal blood lipid levels and glucose intolerance. This condition, now called metabolic syndrome, is often associated with elevations in alkaline phosphatase and other liver enzymes. In 2004, Dr. Darwin Deen of Albert Einstein College of Medicine predicted that metabolic syndrome would overtake cigarette smoking as the primary risk factor for heart disease in the United States.
Insulin Resistance
One of the primary disorders in metabolic syndrome -- and perhaps its driving force -- is insulin resistance. Insulin is a hormone released by your pancreas in response to rising blood glucose levels. Whenever you eat a meal containing carbohydrates or proteins, insulin is secreted to enhance the absorption of glucose by the cells in your liver, muscles and adipose tissue, where it is either burned for energy or stored for later use. If your cells are resistant to insulin, glucose is preferentially routed into metabolic pathways that favor its conversion to triglycerides, which are your body's primary form of fat storage.
Fatty Liver
Your liver is the principal site of fatty acid metabolism in your body. Fatty acids are delivered to your liver attached to triglyceride molecules, from which they are cleaved to provide the raw materials for making cholesterol, phospholipids and other important molecules. If you have metabolic syndrome, your liver receives more triglycerides than it can readily metabolize, so it stores the excess. This leads to a condition called fatty liver, or steatosis, which injures your liver's cells and prompts the release of their enzymes, including alkaline phosphatase. According to a June 2006 "American Family Physician" review, fatty liver due to metabolic syndrome is one of the most common causes of elevated liver enzymes in the U.S.
Higher Mortality
In November 2005, scientists at the University of Texas Health Science Center reported that elevated liver enzymes are not only common in individuals who already have metabolic syndrome, but they can also predict the development of metabolic syndrome in individuals who don't yet have it. Furthermore, the June 2011 issue of "The American Journal of Medicine" reported that individuals who have elevated alkaline phosphatase levels exhibit a higher mortality rate than people whose levels are normal, whether they have metabolic syndrome or not. Therefore, elevated alkaline phosphatase levels may indicate underlying physiologic abnormalities that mirror those of metabolic syndrome and contribute to cardiovascular disease, diabetes and other chronic illnesses.
Considerations
Elevated alkaline phosphatase levels occur in a variety of clinical settings, but fatty liver -- whether or not it is associated with metabolic syndrome -- is a common cause. Fatty liver and metabolic syndrome can both be ameliorated by weight loss, regular exercise and dietary modifications, such as reducing fat and carbohydrate consumption. As fatty liver resolves, your liver enzymes return to normal. If you have metabolic syndrome, fatty liver or an elevated alkaline phosphatase level, talk to your doctor about your options.
References
- "American Family Physician"; Metabolic Syndrome: Time for Action; D. Deen; June 2004
- "American Family Physician"; Nonalcoholic Fatty Liver Disease; M. Bayard, et al.; June 2006
- "Diabetes"; Liver Markers and Development of the Metabolic Syndrome: The Insulin Resistance Atherosclerosis Study; A.J.G. Hanley, et al.; November 2005
- "The American Journal of Medicine"; Associations of Serum Alkaline Phosphatase with Metabolic Syndrome and Mortality; V.R. Krishnamurthy, et al.; June 2011
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