The pancreas, and to a lesser extent, the salivary glands, produce an enzyme called amylase. This enzyme plays a critical function in digestion, breaking down carbohydrates and complex starches into forms of sugar that the body can more easily use for energy. There are fewer causes for low amylase levels than for high amylase levels. Among the conditions that can result in low amylase are cystic fibrosis, liver disease, fat intolerance, damage to the pancreas, excess consumption of carbohydrates and pancreatic cysts.
Cystic fibrosis is a genetic disease that affects the ability of some of the body's cells to transfer water and electrolytes. The sticky, thick mucus that collects in the lungs also accumulates in the pancreas, blocking the ducts and interfering with the pancreas' ability to release amylase. A pancreas damaged by injury or disease and malignant or benign cysts that obstruct the organ's ducts can result in low amylase levels as well. Amylase is also contained in the liver, and cirrhosis of the liver or hepatitis can cause lower levels of amylase.
Two causes of lower than normal amylase levels can, at least to some degree, be controlled by diet. Fat intolerance is the inability of the body to break down oils and fats. Not all patients are intolerant of the same fats; some cannot break down milk fats, others cannot process fatty meats, and still others cannot tolerate cooking oils. Many people who cannot eat fat, and some who can, take in an excess of carbohydrates; because amylase is needed to break down carbohydrates, loading up on carbohydrates can overwhelm the system, resulting in low amylase levels.
In addition to processing carbohydrates, another function of amylase is to break down pus, or white blood cells, so that the body can eliminate them. This results in a condition called macroamylasia, which occurs when amylase clumps form in the blood. The kidneys cannot process these over-sized clumps, so the amylase levels in the urine decrease while blood amylase levels increase. Low amylase levels increase the risk of such abscesses, which do not respond to antibiotics, as they contain no bacteria.
Doctors may order amylase tests on both the patient's urine and blood; it is possible for levels to be high or low in both, or one may be elevated and the other depressed. The amount of amylase in each sample helps identify potential causes. In many cases, however, low amylase levels in the blood are not reason for alarm, and no definite cause can be found.