Endocrine or metabolic causes

Acromegaly

Anorexia nervosa

Athletic amenorrhea

Diabetes mellitus (type 1—formerly known as insulin-dependent diabetes mellitus)

Hemochromatosis

Hyperadrenocorticism

Hyperparathyroidism

Hyperprolactinemia

Thyrotoxicosis

Collagen/genetic disorders

Ehlers-Danlos syndrome

Glycogen storage diseases

Homocystinuria

Hypophosphatasia

Marfan syndrome

Osteogenesis imperfecta

Medications

Cyclosporine (Sandimmune)

Excess thyroid hormone

Glucocorticoids

GnRH agonists

Methotrexate (Rheumatrex)

Phenobarbital

Phenothiazines

Phenytoin (Dilantin)

Heparin, prolonged treatment

Nutritional

Alcoholism

Calcium deficiency

Chronic liver disease

Gastric operations

Malabsorption syndromes

Vitamin D deficiency