context: If you want to donate part of your liver to someone who needs a new one, you'll need to check to see if you've got the right profile. The government and transplant centers have rules about who can and can't be a donor. You're the only one who can decide to donate part of your liver. It's illegal for anyone to force you to do it. It's also against the law to sell organs. Transplant centers always make sure that their donors are doing this of their own free will, and you'll need to sign a consent form. You have the right to back out at any time. If you're a blood relative, it's more likely that your blood type will be a good match for the person getting part of your liver. Some transplant centers, though, let you donate part of your liver to someone you don't know who's on the organ transplant waiting list. Most transplant centers want you to be between 18 and 60 years old, although the exact age range varies. The reason is that older donors tend to have more complications than younger ones. Transplant centers also consider children and teens to be too young to give the proper consent. You don't have to have the exact blood type as the person who needs a new liver, but you need to be what's called "compatible." Here's how it works: If you have Type O blood, you are a "universal donor" and can donate to anyone (although Type O liver recipients can only get organs from people who are also Type O). If you are Type A, you can donate to those who are also Type A as well as Type AB. Type B blood types can donate to other Type Bs and to Type ABs. Type AB people can donate to those with that same blood type. Your Rh factor (whether your blood type is "positive" or "negative") doesn't play a role. If you want to be a donor, your liver, kidneys, and thyroid need to be working right. Transplant centers also want to know that you don't have medical problems like these: Liver disease, including hepatitis Diabetes (or a strong family history of the disease) Heart, kidney, or lung disease Gastrointestinal disease, autoimmune disorders, neurologic disease, and certain blood disorders HIV/ AIDS Cancer (or once had some types of cancer) High blood pressure that's not under control Current or long-term infections, including hepatitis C Use of alcohol or recreational drugs, including marijuana You can't be a donor if you're obese or pregnant. You may also be disqualified if you take pain medications or drugs that are toxic to your liver. To make sure you're healthy enough to donate, you'll have to have a general physical exam. You also may need to take blood and urine tests, a mammogram (for women over 40), a colonoscopy (for men and women over 50), heart tests, and X-rays. You'll need to get checked by a psychiatrist, psychologist, or social worker to make sure you don't have mental health issues, such as anxiety, that might affect your own recovery. They will ask you about behavior that puts you at high risk for infectious diseases. And they'll want to know that you have a good social, emotional, and financial support system lined up for the period after surgery. Quitting tobacco 1-2 months before surgery can help lower the oddsof complications. Quitting smoking even right before surgery can increase the amount of oxygen in your body. After 24 hours without smoking, nicotine and carbon monoxide are already gradually broken down in the blood. Your lungs start to work better after about 2 smoke-free months. Many transplant centers prefer to do living-donor transplants between two people who are roughly the same size (by height and weight), although it's not a hard and fast rule.