Having low testosterone levels, kidney failure, liver failure, multiple sclerosis or Parkinson's disease. The other half were exposed to 2.7 Gy in 26 sessions spread over just five weeks. If you need viagra now buy pfizer viagra online Total testosterone levels: Blood samples for total testosterone levels should be obtained in the early morning (before 8 am) because of wide fluctuations in the testosterone levels throughout the day. A low total testosterone level suggests hypogonadism. Measurement of bio-available testosterone may be a better measurement than total testosterone, especially in obese men and men with liver disease, but measurement of bio-available testosterone is not widely available.