The number of Americans eligible to donate blood may be much smaller than previously believed. A new analysis published in the August issue of the journal Transfusion, suggests that only 37 percent of the country’s population meet the safety restrictions to donate blood.

“The conventional method of calculating eligible donors indicates there are approximately 177 million eligible donors in the U.S. population,” says Dr. Jeffrey McCullough, a professor of laboratory medicine and pathology, at the University of Minnesota. “This study indicates that only 111 million individuals in the U.S. are eligible to donate blood.”

McCullough identified 31 factors that could exclude somebody from donating in addition to age.

Those include things like traveling to a malarial-infested region within the past three years or arriving to donate with a cold or flu.

They found that nearly 54 million Americans would be deferred for permanent exclusions, defined as those lasting for more than a year. Another 12.6 million would be deferred for donating for up to a year, and an additional 18 million for up to 60 days.

Accounting for overlap between exclusions, the researchers estimated that about 66 million individuals would be deferred based on current standards. And the donor pool could be even smaller, given that researchers were unable to find appropriate data sources to calculate the effect of restrictions due to vaccination, recent blood donations, transplants, transfusions, body piercings and certain prescription medications.

“As additional donor restrictions are implemented and the population ages, the country could lose more and more willing donors, which could pose an even greater threat to our national blood supply,” says Karen Shoos Lipton, chief executive officer of the American Association of Blood Banks. “Ensuring an adequate supply of blood is increasingly more challenging, and these new data suggest it is extremely important that eligible donors give blood more frequently.”

The good news buried in the restriction data is that donation rates are higher than previously believed. Assuming the larger donor pool, donation rates in 1999 were pegged at 80.8 units of blood per 1,000 eligible donors. Using the smaller donor pool found by the study, donation rates are almost 60 percent higher, at 128.8 units per 1,000 eligible donors.

And there’s evidence that hospitals and blood centers are doing a better job ensuring the blood that is collected isn’t wasted. A recent report on blood collection and utilization rates from the U.S. Department of Health and Human Resources found that the number of units never used because they became outdated in 2005 dropped by 43 percent from 2002 levels.

The report found that hospitals are reporting fewer shortages of blood, but when those shortages occur they last longer than before. The mean number of days of unmet nonsurgical blood need increased from 2.1 days in 2001 to 19.3 days in 2004.

But the report also concluded that blood centers were able to retain as regular donors many of those who volunteered after the Sept. 11 attacks in 2001. In 2004, blood centers collected 15.3 million units, virtually unchanged from the amount reported in 2001.

Donating blood has become a much more arduous a process given all the new restrictions. Donors must respond to an ever-increasing list of questions to parse out their eligibility, including sometimes embarrassing queries about their previous sexual contact.

From time to time, some of those restrictions are relaxed. For example, regulations once prevented cancer survivors from ever donating. Now survivors can donate after being cancer-free for five years.

Blood centers have urged the Food and Drug Administration to lift the lifetime donation ban for men who have had sex with other men. Last year, the American Association of Blood Banks, America’s Blood Centers and the American Red Cross issued a joint statement supporting a 12-month deferral instead, arguing that screening blood with two different types of tests should detect cases of HIV. Currently, blood donors judged to be at risk of exposure through heterosexual routes are deferred from donating for one year, while men who have had sex with another man even once since 1977 are permanently deferred.

But for the most part, the FDA has been adding restrictions faster than removing them.

In Central Oregon, that has reduced the blood donor pool, but Mike Mawdsley, donor services manager for the American Red Cross in Bend, says a higher percentage of eligible donors come in to donate blood.

“The blood supply needs to continue increasing because usage is increasing,” he says. “There are more and more patients. Obviously, Central Oregon growing is growing by leaps and bounds. St. Charles reports that their usage of blood products is increasing, and so we need to keep sending them more.”

St. Charles Medical Center-Bend has been particularly effective at limiting their use of type O blood, which is often in short supply. Because type O can be given to all patients regardless of blood type, it is used in emergency situations when there isn’t time to type and cross-match blood. The sooner that test can be performed, the sooner a hospital can switch to the patient’s natural blood type, saving units of type O blood.

The blood supply chain runs on a razor-thin margin, often providing only a one-day supply of type O blood.

“A three-day supply is what we could consider adequate, certainly not overkill but adequate,” Mawdsley says. “And type O supplies have been around a one-day supply, as low as a couple of units at a time, over the last year. A three-day supply would be much better, and we would be better prepared in the event of some unplanned emergency.”

A new push for donors launched in February has helped local donation rates rebound from an unexplained off-year. In the 12 months ending on June 30, local blood centers collected 1,840 more units than in the previous 12 months.

Still, local clinics must turn away willing donors every day. About 15 percent of volunteers will bump up against one of the restrictions. One of the most common is for low iron levels, a restriction designed to protect both the recipient and the donor.

“We definitely err on the side of caution,” Mawdsley says. “It’s very important that folks answer the questions truthfully, so we can go through the criteria, and make sure that it’s both healthy for them and healthy for the recipient.”

In October, local blood clinics plan to introduce new technology that could further increase the number of units collected. The process, known as double red cells, filters out red cells while leaving blood plasma.

As a result, donors can donate twice as many blood cells in a single visit while actually losing less blood volume.

“We’re very excited to be able to introduce it,” Mawdsley says. “It’s a proven technology that is just reaching us now in the Northwest.”

He also urges individuals not to assume they’re ineligible to donate even if they’ve been told so before.

“The FDA is constantly updating criteria,” he says. “Nothing is forever, it seems, and they should check back and see if their eligibility status has changed.”

Inside

• Can you donate blood? See chart on Page E8.

Who’s eligible to donate blood

Researchers calculated that 31 factors would prevent 85 million individuals from donating blood. Accounting for overlaps between categories, that could rule out more than 66 million potential donors.

Excluded for more than 365 days

Heart disease – 12,807,000

Cancer – 6,349,000

Travel to malarial region – 4,921,000

Institutionalized – 3,977,858

Developmentally disabled – 3,600,000

Expatriation – 3,496,000

Male sexual content – 3,825,000

Hepatitis C – 2,430,000

Liver disease – 2,063,000

Stroke – 2,018,000

Kidney disease – 1,779,000

U.K. travel (Mad Cow) – 1,406,000

Active military – 1,386,000

Hepatitis B – 1,125,000

HIV/AIDS – 1,045,000

Immigrant from malarial region – 832,500

Inflammatory bowel disease(Crohn’s/ulcerative colitis) – 750,000

Sickle cell anemia – 56,000

Excluded from 61 to 365 days

Underweight – 4,625,000

Tattoo – 3,698,520

Pregnancy – 2,981,574

Needle stick – 800,000

Abortion – 357,871

Gonorrhea – 108,909

Syphilis – 29,130

Lyme disease – 14,891

Tuberculosis – 11,899

Excluded for up to 60 days

Anemia – 13,260,982

Diabetes – 450,000

Illness, cold/flu – 2,160,000

Allergies, symptomatic – 1,565,100

Hypertension/pulse – 603,100

Source: Pediatrics

Wondering if you qualify to donate?

E-mail canidonate@redcross.org and get your questions about eligibility answered anonymously. Or call 800-GIVE-LIFE.