Numerous conditions or factors can cause low levels of high-density lipoprotein, or HDL, cholesterol. According to MayoClinic.com, HDL cholesterol, or good cholesterol, acts as a cholesterol scavenger, transporting excess cholesterol in the blood back to the liver where it is metabolized, or broken down. The higher a person's HDL cholesterol, the less LDL cholesterol, or bad cholesterol, she will have in her blood. Lifestyle factors and certain medical conditions can cause a reduction in a person's HDL cholesterol levels.
Hyperlipemia is a condition in which a person's HDL cholesterol levels may drop. According to the MedlinePlus website, hyperlipidemia is the medical term for elevated cholesterol levels -- except HDL cholesterol, which will be lower than normal -- cholesterol esters, phospholipids and triglycerides, and it occurs when a person has too many fatty substances in his blood. A person with hyperlipidemia has an increased risk of atherosclerosis or plaque formation on the walls of his arteries. Atherosclerosis, in turn, may lead to heart disease, stroke and hypertension. Numerous factors can cause hyperlipidemia, including being overweight or obese, certain medications, alcohol abuse, smoking and certain medical conditions, such as hypothyroidism, Cushing syndrome and kidney disease. The MedlinePlus website states that lifestyle changes, including diet and exercise, are an important treatment method for a person with hyperlipidemia to boost HDL cholesterol levels.
A sedentary lifestyle can cause HDL cholesterol levels to drop. Aetna Women's Health states that a sedentary lifestyle does not exercise the heart muscle. If the heart is not exercised, it can lose strength, flexibility and endurance. A sedentary lifestyle is a lifestyle in which a person is inactive both and work and at home and fails to engage in aerobic activity for 20 continuous minutes at least three times per week. According to Dr. Dicken Weatherby, a naturopathic physician and author of the book "Blood Chemistry and CBC Analysis," a sedentary lifestyle has been shown to decrease HDL levels. Increasing cardiovascular and resistance exercise, states Weatherby, is an effective way to boost HDL levels. The American Council on Exercise, or ACE, notes that exercise promotes fat weight loss, and fat weight loss -- especially fat loss around the waist and abdomen -- is associated with increases in HDL cholesterol and decreases in total cholesterol and LDL cholesterol.
Syndrome X may cause decreased HDL cholesterol levels. According to MayoClinic.com, syndrome X, also known as metabolic syndrome, is a group of conditions that occur simultaneously and increase a person's risk for heart disease, stroke and diabetes. A person with syndrome X usually has increased blood pressure, elevated insulin levels, excess body fat around the midriff and abnormal cholesterol levels, including decreased HDL cholesterol. Along with low HDL cholesterol, common signs and symptoms associated with syndrome X include obesity, a blood pressure greater than 120/80 mm Hg, elevated triglycerides and resistance to insulin -- a hormone that helps regulate the amount of sugar in the blood. Certain risk factors may increase a person's likelihood of developing syndrome X, including advanced age, Hispanic or Asian ancestry, obesity, a history of diabetes and other medical conditions, such as hypertension, cardiovascular disease and polycystic ovary syndrome.