Sex hormones: Lowered sex hormone levels tend to weaken bone. The fall in estrogen levels in women at menopause is one of the strongest risk factors for developing osteoporosis.
Thyroid problems: Too much thyroid hormone can cause bone loss. This can occur if your thyroid is overactive or if you take too much thyroid hormone medication to treat an underactive thyroid.
Other glands: Osteoporosis has also been associated with overactive parathyroid and adrenal glands.
Low calcium intake: A lifelong lack of calcium plays a role in the development of osteoporosis. Low calcium intake contributes to diminished bone density, early bone loss and an increased risk of fractures.
Eating disorders: Severely restricting food intake and being underweight weakens bone in both men and women.
Gastrointestinal surgery: Surgery to reduce the size of your stomach or to remove part of the intestine limits the amount of surface area available to absorb nutrients, including calcium.
Steroids and other medications:
Long-term use of oral or injected corticosteroid medications, such as prednisone and cortisone, interferes with the bone-rebuilding process.
Courtesy: Mayo Clinic