HDL is produced in the liver and intestine and acts like a scavenger of cholesterol. HDL can bind to cholesterol in cell membranes by using the apo-AI protein to mediate the formation of cholesteryl esters. The apo-D protein in HDL then activates the transfer of cholesteryl esters to VLDL and LDL. HDL also transfers apo-CII and apo-E proteins to chylomicrons and other low density lipoproteins. In the liver, the apo-E protein is used to recognize and absorb the remants of lipoproteins so that excess cholesterol can be removed and converted to bile acids that are excreted into the duodenum (small intestine) through the bile duct.
In addition to the mentioned side effects several others have been reported. In both males and females acne are frequently reported, as well as hypertrophy of sebaceous glands, increased tallow excretion, hair loss, and alopecia. There is some evidence that anabolic steroid abuse may affect the immune system, leading to a decreased effectiveness of the defense system. Steroid use decreases the glucose tolerance, while there is an increase in insulin resistance. These changes mimic Type II diabetes. These changes seem to be reversible after abstention from the drugs.