Three main factors are responsible.
(1) Heredity : In Most of the patients bad cholesterols high and good cholesterol is low by virtue of heredity. This is a widely prevalent reason in our country.
(2) Bad lifestyle : Higher intake of substances with bad cholesterol in diet and lack of exercise invite this disease or worsens it. Addiction of bidi / cigarette also reduces good cholesterol and increase bad cholesterol. Consumption of alcohol in excessive quantity increases triglyceride.
(3) Some other diseases or States : Bad cholesterol can increase and good cholesterol can decrease in states like diabetes, a disease of the liver, kidney failure, use of steroid hormones or contraceptive pills for long duration, hypothyroidism, obesity and the years after menopause in women, etc.
In some patients multiple factors are responsible.