Donated blood is rarely given whole any more. It is split into parts, and the smallest of these, purified proteins from the liquid part of blood, are called blood fractions. One donation can become several different medicines, each matched to a specific problem such as bleeding, a weak immune system, or dangerous fluid loss. The word also matters outside the lab, because some people who refuse transfusions on religious grounds draw the line between whole blood and these minor fractions.1Cleveland Clinic Journal of Medicine. Ethical perspectives on Jehovah’s Witnesses’ refusal of blood
How Blood Is Split Into Components and Fractions
Spin blood very fast in a machine and the heavier parts move outward faster than the lighter ones. The blood settles into layers: red cells at the bottom, a thin pale layer of white cells and platelets, and yellowish plasma on top. More refined spinning methods can sort fresh blood into six purified groups, from plasma proteins and platelets to red cells and three kinds of white cells.2PubMed. Isolation of human blood cells, platelets, and plasma proteins by centrifugal SPLITT fractionation Red cells, platelets, and plasma, the main transfusion products, are known as blood components.
Plasma, the liquid layer, makes up about 55% of blood. It is mostly water carrying hundreds of proteins. To pull out single proteins, makers change the plasma’s acidity, alcohol content, temperature, and salt level step by step, so each protein falls out of solution at a different stage.3Wikipedia. Cohn process That lets albumin, antibodies, and clotting factors each be collected and purified separately. Because these processes work on large batches, fractions are usually made from the pooled plasma of many donors, while components come from one donor or a few.
Giving only the part a patient needs beats giving whole blood for several reasons. Someone short on red cells gets red cells, not extra plasma they don’t need. Concentrated products take less volume, which lowers the risk of overloading the heart and circulation. Less exposure to unneeded cells also means fewer transfusion reactions.
Each part is stored under its own conditions, since they keep for very different lengths of time and need different temperatures. Plasma left over after the cells are removed can go on to be refined into fractions, so little of a donation is wasted.
On a consent form, the difference usually shows in how the product arrives. Components such as red cells and platelets come as bags in a transfusion. Fractions usually come as vials or infusions labelled as medicines, often with brand names. A form may ask about each fraction separately, so knowing which is which helps you answer.
Albumin for Fluid Loss and Liver Disease
Albumin is the most plentiful protein in blood and provides about 70% of the pull that keeps fluid inside blood vessels.4PubMed. Clinical indications for the albumin use: still a controversial issue When albumin is low, as in cirrhosis where the liver makes less of it, water seeps out into the surrounding tissue and causes swelling. That often shows first in the legs and ankles, and in liver disease fluid can also collect in the abdomen.
Its strongest uses are in people with cirrhosis, to treat or prevent kidney failure and circulation problems after large amounts of abdominal fluid are drained.5PubMed. Clinical indications for the albumin use: still a controversial issue It is also used to restore fluid in critically ill patients when ordinary salt-water drips don’t work or can’t be used.6PubMed. Clinical indications for the albumin use: still a controversial issue
In trauma and surgery patients, though, albumin held fluid in the bloodstream better than salt-water fluids yet did not lower the death rate.7PubMed Central. Use of Human Serum Albumin in Critically Ill Patients: A Narrative Review So doctors usually save it for people with very low albumin or unstable blood pressure.8PubMed Central. Use of Human Serum Albumin in Critically Ill Patients: A Narrative Review
Receiving it is straightforward. It is a clear yellowish liquid given through an IV over a period of time, often with or after draining abdominal fluid in cirrhosis. It is costly, which is one reason doctors try cheaper fluids first. Albumin is heat-treated during manufacturing, which is part of why it has a long safety record.
Immunoglobulin for Weak Immune Systems and Autoimmune Disease
IVIG (intravenous immunoglobulin) is a purified pool of antibodies taken from the plasma of many donors.9PubMed. Intravenous immunoglobulins as therapeutic agents It gives people who can’t make enough antibodies of their own ready-made protection.10PubMed. Intravenous immunoglobulins as therapeutic agents The IV form is often chosen because large amounts can be given quickly, and some patients learn to give immunoglobulin themselves.11PubMed. Intravenous immunoglobulins as therapeutic agents
The people who need replacement antibodies include those born with immune systems that cannot make enough, and those who lose that ability through diseases of the blood or immune system. Without replacement they tend to get repeated or serious infections, such as in the lungs and sinuses. IVIG does not cure the underlying problem. It borrows protection from donors, which is why it has to be repeated.
Over time doctors found IVIG also dampens harmful inflammation.12PubMed. Intravenous immunoglobulin as a therapy for autoimmune conditions It is approved for Kawasaki disease, immune thrombocytopenia (very low platelets caused by the immune system), and Guillain-Barré syndrome.13PubMed. Intravenous immunoglobulin as a therapy for autoimmune conditions Doctors sometimes use it outside its approved uses for muscle inflammation, blood-vessel inflammation, and other blood disorders.14PubMed. Intravenous immunoglobulin as a therapy for autoimmune conditions
Treatment often means infusions that take several hours in a clinic. People with antibody deficiency may need them every few weeks for life. Some versions go under the skin and can be given at home. Headache and tiredness after an infusion are common but short-lived.
Clotting Factors and Cryoprecipitate for Bleeding
Factor concentrates made from plasma treat hemophilia A, hemophilia B, and von Willebrand disease, inherited conditions where blood doesn’t clot properly.15PubMed. Clinical uses of plasma and plasma fractions: plasma-derived products for hemophilias A and B, and for von Willebrand disease In wealthy countries these have largely been replaced by lab-made (recombinant) versions.16PubMed. Clinical uses of plasma and plasma fractions: plasma-derived products for hemophilias A and B, and for von Willebrand disease Lab-made factor carries no risk from human donors and less risk of the body forming antibodies against it.17PubMed Central. Plasma-derived versus recombinant Factor VIII concentrates for the treatment of haemophilia A: recombinant is better. In poorer countries, home to most people with hemophilia, plasma-made factor remains the main treatment because it costs less.18PubMed. Clinical uses of plasma and plasma fractions: plasma-derived products for hemophilias A and B, and for von Willebrand disease
Day to day, hemophilia means a missing clotting factor and bleeding that lasts longer than expected, especially into joints and muscles. Treatment replaces the missing factor, either after a bleed or on a regular schedule to prevent bleeds. Hemophilia A and B lack different factors, so each needs its own matching concentrate; one cannot substitute for the other.
Older fears date from the 1980s, when HIV spread through untreated products. Modern plasma-made factor goes through virus-killing steps, covered in the safety section.
Cryoprecipitate (cryo) is a clotting-protein-rich layer that forms when frozen plasma is thawed slowly. It is rich in fibrinogen, the protein that forms the mesh of a blood clot. A standard dose holds about half the fibrinogen of a purified fibrinogen concentrate, and its other clotting proteins vary from bag to bag.19PubMed Central. Differences in coagulation-relevant parameters: Comparing cryoprecipitate and a human fibrinogen concentrate Still, in heart surgery patients it raised fibrinogen at least as well, with no difference in levels after 48 hours.20PubMed. Prospective, Randomized Study of Fibrinogen Concentrate Versus Cryoprecipitate for Correcting Hypofibrinogenemia in Cardiac Surgery Patients
Cryo comes up in heavy bleeding from surgery, childbirth, or injury. It is thawed and given like a small transfusion. Hospitals choose it or a purified concentrate depending on what’s stocked.
Alpha-1 Antitrypsin for an Inherited Lung Condition
Alpha-1 antitrypsin deficiency is an inherited condition that most often causes emphysema, a lung disease that damages air sacs.21PubMed Central. Alpha-1 Antitrypsin Substitution for Extrapulmonary Conditions in Alpha-1 Antitrypsin Deficient Patients The missing protein normally protects lung tissue from enzymes released by white cells during inflammation. When it is low, those enzymes slowly damage the air sacs, so lung disease can develop earlier than usual. The condition can also affect the liver, though the infusion treatment is aimed at the lungs.
Infusions of the protein, purified from donor plasma, bring its levels in the blood and lungs back up.22European Respiratory Review. Long-term experience in the treatment of α1-antitrypsin deficiency: 25 years of augmentation therapy Treatment means slow weekly infusions for life, aimed at slowing lung damage.23PubMed Central. Alpha-1 Antitrypsin Substitution for Extrapulmonary Conditions in Alpha-1 Antitrypsin Deficient Patients A nurse can sometimes do them at home.
People who develop emphysema young, or without heavy smoking, may have this deficiency and can ask about it. A simple blood test checks the level.
Red Cell and Platelet Transfusions
Red cells are given to prevent organs from running short of oxygen.24PubMed Central. Transfusion of Packed Red Cells For otherwise healthy people a transfusion is usually needed when hemoglobin falls to 6 g/dL or below.25PubMed Central. Transfusion of Packed Red Cells For many patients, waiting until hemoglobin reaches 7 to 8 g/dL works as well as transfusing at about 10.26PubMed Central. Transfusion of Packed Red Cells
One unit raises hemoglobin by about 1 g/dL in an average adult who isn’t bleeding.27Australian Red Cross Lifeblood. Use of red cells So best practice is one unit, then a recheck before giving more.28Australian Red Cross Lifeblood. Use of red cells
The number is not the whole decision. Doctors weigh it alongside symptoms such as breathlessness, chest pain, or dizziness. Someone with heart disease may be treated at a higher number than a healthy person. Ongoing bleeding changes the picture too, since the number can drop further, so the call is made on the situation as a whole.
Platelets come either pooled from several whole-blood donations or from one donor through a machine that collects only platelets.29PubMed. Evidence-based platelet transfusion guidelines A usual dose is one single-donor unit or a pool of four to six whole-blood units.30PubMed. Overview of platelet transfusion Both kinds work equally well.31PubMed. Evidence-based platelet transfusion guidelines
People having chemotherapy or with leukemia often need platelets. They keep only about five days, so donations are always needed.
How Safe Are Products Made From Pooled Plasma
A solvent-detergent treatment dissolves the fatty outer coat of viruses such as HIV and hepatitis B and C, destroying them.32PubMed Central. The Use of Solvent/Detergent Treatment in Pathogen Reduction of Plasma Even Zika virus added on purpose dropped below detectable levels in treated plasma, IVIG, and clotting factor.33PubMed. Inactivation of Zika virus by solvent/detergent treatment of human plasma and other plasma-derived products and pasteurization of human serum albumin Viruses without a fatty coat, like hepatitis A and parvovirus, survive this step.34PubMed Central. The Use of Solvent/Detergent Treatment in Pathogen Reduction of Plasma So makers limit them by screening donations, diluting through pooling, and relying on antibodies already in the pool.35PubMed Central. The Use of Solvent/Detergent Treatment in Pathogen Reduction of Plasma An added filter step can also strip out most abnormal prion protein, the cause of mad-cow-type disease.36PubMed Central. The Use of Solvent/Detergent Treatment in Pathogen Reduction of Plasma No single step removes every germ, so makers combine donor screening, testing, pooling, and treatment.
Pooling cuts both ways. Mixing many donors means one infected donation could in theory contaminate a large batch, which is why donations are tested and the pool is treated before use. Pooling also brings in antibodies from many donors, which can neutralize some viruses present in small amounts. You can ask your doctor which product you’re getting and how it was treated.
Fractions and Jehovah’s Witnesses
Jehovah’s Witness teaching forbids whole blood and its main components but doesn’t absolutely forbid minor fractions such as albumin, immunoglobulin, and hemophilia clotting factors.37Cleveland Clinic Journal of Medicine. Ethical perspectives on Jehovah’s Witnesses’ refusal of blood So each Witness, with good information and counsel, decides for themselves.38Cleveland Clinic Journal of Medicine. Ethical perspectives on Jehovah’s Witnesses’ refusal of blood A patient may accept some fractions and refuse others.
Before a hospital stay, you can list which fractions you’d accept in an advance directive and ask which ones a planned treatment might involve. Hospital liaison committees can help explain the options.
Where Plasma Comes From and Why Donors Are Paid
Most countries don’t allow plasma donors to be paid.39Niskanen Center. The case for commercial compensated plasma collections Yet every country that allows paid collection collects more than it needs and exports the rest, while countries without it face growing shortfalls.40Niskanen Center. The case for commercial compensated plasma collections A fraction used in your hospital may therefore come from plasma donated abroad.
If you’re thinking of donating, only the plasma is collected and the red cells go back to you. You can donate more often than whole blood. Your plasma may become albumin, IVIG, or clotting factor.
Platelet-Rich Plasma and Newer Uses
PRP (platelet-rich plasma) is made by spinning a small amount of a person’s own blood and injecting the platelet-rich part into a joint, usually within the same visit. The idea is that platelets release growth signals that may reduce inflammation or help tissue repair. Because it comes from your own blood, there’s no donor and no matching, which is a main reason it is considered low risk.
In knee arthritis it can cut pain from about 7 to 4.5 on a 10-point scale over six months.41PubMed Central. Platelet rich plasma applications in orthopedics: A review of recent advances Results vary, though, and preparations differ in content.42PubMed Central. Pure Platelet and Leukocyte–Platelet-Rich Plasma for Regenerative Medicine in Orthopedics—Time- and Preparation-Dependent Release of Growth Factors and Effects on Synovial Fibroblasts: A Comparative Analysis Before paying, it helps to know that PRP often isn’t covered by insurance, and to ask how the clinic prepares it and what results to expect and when.
Researchers are also studying tiny particles released by blood cells as carriers for drugs.43PubMed Central. Blood cell-derived extracellular vesicles: diagnostic biomarkers and smart delivery systems This remains early research.