Know Before You Go: Donating Blood

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While not the only body tissue that can be donated (think: bone marrow and reproductive cells like sperm and eggs), blood is needed on a day to day basis by large numbers of patients. Every two seconds, someone in the US is in need of blood, and nearly 25 percent of us will require a blood transfusion at some point in our lives. Sharing your bloodline is a considerable gift: Each donation can save up to three people (talk about lifeblood)! Not bad for one pint of vital fluid. Here’s how to starve a vampire (or a mosquito, if vampires aren’t your thing) in favor of saving a few lives.

Illustration by Elaine Liu

True Blood — The Need-to-Know

These days, donating blood is easy, and (mostly) painless and risk-free. Afraid of needles? No problem — many say blood donation hurts less than a shot (and the good vibes from donating will help make up for it).

So why else give up a pint of the good stuff? Blood is something we can easily spare because the body continuously replenishes it. The average adult has between 10 and 12 pints (or five liters) of blood continuously cycling through their body. Each blood cell is broken down and replaced every 120 days on average (you know, to keep things fresh). Donated blood, on the other hand, stays fresh for only 42 days. Huge amounts are needed in hospitals daily, so this short lifespan means blood is always needed and needs to be donated regularly.

The ABO’s of Blood

The same basic components make up all blood — red cells (erythrocytes), white cells (leukocytes), platelets, and plasma. Red cells shuttle oxygen to the body’s tissues with help from the iron-containing protein hemoglobin. White cells are the immune system’s first responders — they roam the body and attack intruders including bacteria and viruses. Platelets help clot blood (like making cuts stop bleeding). And plasma, the blood’s space filler, provides nourishment for the other cells and serves as a liquid medium through which they flow.

Blood comes in a few different types: A, B, AB, and O. Just like personalities, not all blood types get along. This is because each type of blood has it’s own antigens, which sit on the cell's surface and tell the body’s immune system whether the cell is foreign or familiar. The immune system creates antibodies to fight off the antigens that don't match up, which helps the body to protect itself from foreign invaders.

If antibodies come across a blood cell whose antigens are not compatible (for example, type B blood that was wrongly infused into a type A patient) it will tell the immune system to rev up either break down the blood or cause clotting — not a good look for the circulatory system.

The third major antigen that camps out on the surface of blood cells determines what’s called the Rh status of a person. Blood cells that have this antigen are deemed “positive” whereas cells without it are designated “negative.” Rh-negative blood types can only receive red blood cells from other Rh-negatives, but Rh-positive can receive either.

Who's Eligible to Give?

Even blood banks have to be picky. Beyond the standard eligibility requirements for blood donation — which require donors to be healthy, at least 17 years old (in most states), and weigh no less than 110 lbs — some other restrictions apply. Donors may be turned away for a number of reasons.

If you have a fever or active infection like the flu, low blood pressure (below 80/50), or if hemoglobin levels (the part of red blood cells that carry oxygen throughout the body) are too low, expect to be turned away. Jet-setters and tattoo-lovers be forewarned, too. Those who have recently visited or lived in counties at risk for malaria, HIV, hepatitis, or mad cow’s disease may be asked to return at a later date. And some of those recently inked may have to wait up to a year after getting a tattoo (if they’re in one of the 18 states without stringent tattoo regulations). Need more deets before heading to the donation center? Here are the eligibility requirements in extreme detail, so take a gander before heading out the door.

Take it to the (Blood) Bank — Your Action Plan

The blood donation process has a few steps: registration, assessment of eligibility, donation, and refreshments post-donation (free food!). While the process from beginning to end may take an hour, the donation (that’s the part when the needle is in your arm) is typically a quick 10 minutes.

  • Where to go. Find a donation location near you through the Red Cross, which collects about 45 percent of the blood in the country.
  • Dress to impress. Muscle tanks and sleeveless turtlenecks are welcome. Make sure there's easy access to the underside of your arm, particularly at the elbow.
  • Chow down and drink up. It’s a good idea to arrive well-fed and hydrated to help limit any lightheadedness. Avoid fatty foods before donating — the fat can affect the blood processing tests. Instead, consider iron-rich foods in the weeks before donation.
  • IDs, please. Bring a driver’s license or two other forms of identification to present at registration. For repeat donors, bring a donor card if you have one!
  • Prescription for success. Make note of any prescribed medications to inform the staff during registration or the physical exam.
  • Say ahhh. Assessment includes a private and confidential interview about your health history, as well as a mini physical. Expect evaluation of pulse, blood pressure, and hemoglobin level (which requires a quick, on-the-spot finger stick test).
  • Seeing red. Donation is done in a seated or lying position and performed by a trained healthcare professional. A sterile needle is inserted in the bend of your elbow for 8-10 minutes while one pint of blood and a few test tubes are collected.
  • Cover up. Post-donation, donors will brandish a new wardrobe accessory: an arm bandage. Keep this on for at least five hours. If you start to bleed, raise the arm above the head and apply pressure until it stops. The area my bruise, too. If it hurts, apply ice during the first 24 hours. After that, try warm, moist heat. If you’re really not doing well, contact the donation center or your doctor’s.
  • Snack time. Juice packs and kiddie snacks are back. Expect light refreshments after donation as a thank you. Continue drinking extra fluids (approximately four glasses) throughout the day to replenish the body’s fluids. And sorry all, it’s probably a good idea to avoid alcoholic drinks for the day!
  • So long, sangre. Donated blood is transported to a local blood-processing laboratory. The test tubes collected alongside the pint are brought to a blood testing center. This blood undergoes more than a dozen tests to determine blood type and the presence of infectious diseases (including, HIV, hepatitis, syphilis, and more). If anything worrisome is found, the donated blood is discarded and the donor is notified.
  • Rest up. Avoid intense exercise or heavy lifting for the day — turns out blood, sweat, and tears don’t always go hand-in-hand. Drink plenty of non-caffeinated and non-alcoholic fluids for the first 24 hours.
  • Round two. Loved donating? Donors are permitted to donate whole blood every 56 days. Using a separation technology, platelets can be donated every seven to 14 days.

Blood donation goes to show that you don’t have to be a doctor to save lives. Have a big heart and donate an hour of time and a pint of blood to help those in need!

Special thanks to Dr. Patricia Carey and Greatist Expert Dr. Marilee Benson for their help with this article.

About the Author
Emily Milam
My longstanding passion for health has ushered me down an exciting (albeit lengthy!) career path in medicine. As a medical student in New York City,...

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