The American Red Cross says 38 percent of the U.S. population is eligible to donate blood, but less than 10 percent of that eligible population actually donates.

Blood is a precious commodity. "It requires a community to come together to have blood for everyone," Dr. Leslie Greebon, Medical Director of the University Hospital Blood Bank and Assistant Professor at UT Health San Antonio, said. She says blood donors are needed year-round. "People generally want to respond to disasters, natural or man-made disasters, but we need a continuous pipeline to always have blood available for all that need it," Dr. Greebon said.

University Hospital pharmacist and blood donor Conrado Gamboa says blood is especially needed when kids are out of school and families are off their daily routines. "Since we are a trauma one facility, we usually have a high volume that we utilize, and sometimes we do have shortages, especially during the holidays and during the summer months and spring break," he said.

What are the most common blood types? Dr. Greebon told us, "Type-O and Type-A are the most common, and that's followed by Type-B, and Type-B is very rare."

Type-O may be the universal donor, but the other blood types are just as important. "We need those blood types so we can give O to people who really need it," said. Dr. Greebon.

She also told us all of the donated blood that is used in their facility is safe. Dr. Greebon said, "We screen our donors because we want to make sure they answer their questions accurately so that way we can advise them if they should donate or not. In addition, we do infectious disease testing as well. It's very sensitive."

For more information about the blood donor services at University Hospital, or if you have questions about your eligibility, call 210-358-2812.

And for more men's health information call 210-358-3045. You can also find the rest of our Real Men Wear Gowns stories- just go to