Between 10% and 20% of men between ages 40 and 70 have lower than normal testosterone production. Risk factors for hypogonadism include increasing age, obesity, pituitary gland disease, and diabetes. Signs and symptoms of low testosterone include decreased sexual desire or interest, problems with erection, fatigue, osteopenia or osteoporosis, and anemia. Recent studies suggest that testosterone deficiency may contribute to vascular disease, which is a known cause of sexual dysfunction. Diagnosis of testosterone deficiency is typically made by history, examination, and a testosterone blood test.