Characteristics that increase the chance of developing osteoporosis or having fractures are called "risk factors" and include:

• Personal history of fracture as an adult, especially after age 50
• Current low bone mass
• Being female
• Being thin and/or having a small frame
• Advanced age
• Family history of osteoporosis in a first degree relative (parents or siblings)
• Estrogen deficiency as a result of menopause, especially early or surgically induced
• Abnormal absence of menstrual periods (amenorrhea)
• Anorexia nervosa 
• Low lifetime calcium intake
• An inactive lifestyle
• Current cigarette smoking
• Excessive use of alcohol
• Excessive exercise, especially if associated with amenorrhea or being underweight
• Poor diet and/or malnutrition and/or disease causing malabsorption of food
• Having had a stroke
• Having dementia or Alzheimer's disease
• Vitamin D deficiency
• Use of oral Steroids (also called glucocorticoids or corticosteriods, such as prednisone)
  
• Use of Depo-Provera
  
• Use of some cancer chemotherapy medications
  
• Use of some anticonvulsants (antiseizure medications), particularly phenytoin or phenobarbital