Deficiency is poorly understood, but it may be caused by synthesis problems in the body rather than an insufficiency in the diet. Low blood levels have been reported in people with heart failure, cardiomyopathy, gingivitis (inflammation of the gums), morbid obesity, hypertension, muscular dystrophy, diabetes, AIDS, and in some people on kidney dialysis. People with phenylketonuria (PKU) may be deficient in CoQ10 because of dietary restrictions. CoQ10 levels are also generally lower in older people. The test used to assess CoQ10 status is not routinely available from medical laboratories.