My bone density test shows that my hip bones have some bone loss. what could be the cause of it?

Many causes: Low hip density can be associated with a family history of osteoporosis, hormone deficiency, hyperthyroidism, cortisone use, alcoholism, cigarette use and many other factors.

There are: many possible reasons for decreased bone density: hereditary, poor health/frailty, smoking, low body wieght, estrogen deficiency states, alcoholism, nutritional deficiencies, certain medications, renal failure, other hormone abnormalities.