Frequently asked questions

In general terms, a bone marrow donor can be a healthy person from the age of 18 up to the age of 60, provided that he or she does not suffer from any disease that can be transmitted to the recipient and that does not suffer from any disease that could endanger his or her life. made of the donation.

From January 2018, only NEW DONORS with ages between 18 and 40 will be included in the registry. This is due to the objective of rejuvenating and optimizing the composition of our donor registry, since younger donors (under 40 years old) are the most requested and with which better clinical results are obtained in patients who are transplanted. 

Broadly speaking, donors must not have a personal history of heart, liver, autoimmune, infectious or neoplastic diseases. However, at REDMO, we have prepared an overview of the most common questions that we are asked in relation to bone marrow donation. Moreover, if you would like to find out more about this issue, you can also read the donor guide and watch an informative video available HERE (in Spanish).

General questions and answers about bone marrow donation

  • Why are unrelated donors needed?

Within a family group, siblings are the best donors for a patient who needs a transplant of blood progenitor cells (commonly known as a bone marrow transplant), due to the hereditary characteristics of the human leukocyte antigen system (HLA).

However, only between 25% and 30% of patients have the possibility of finding a compatible living-related donor. As such, all other patients do not have access to this therapeutic practice.

In response to a lack of a suitable living-related donor, the alternative is to turn to volunteer donors registered on international donor registries. Together, these international registries make up the Bone Marrow Donors Worldwide Network (BMDW), which is comprised by 83 registries in 60 countries, with more than 33 million effective donors.

  • Is bone marrow the same as the spinal cord?

No, it is not the same. The spinal cord runs down the backbone and transmits nerve impulses throughout the body. In contrast, bone marrow is the spongy tissue found inside bones where blood is produced, as it contains stem cells. These cells are also found in the blood of the umbilical cord and placenta of newborn babies. Donating bone marrow does not involve the spine in any way or the nervous system of the human body.

  • Will I get some type of payment for donating bone marrow? 

No, under Spanish law and the international regulations, donations must always be altruistic in nature. However, any expenses that may arise as a result of the donation will be covered, such as travel, accommodation for the donor and a companion if the extraction is performed far from their home, and reimbursement for any money lost through taking time off work.

  • Why is it important to have a registry with a large number of donors?

Populations contain significant genetic variations, including the human leukocyte antigen system (HLA), which plays an extremely important role in the transplant of haematopoietic progenitor cells. This characteristic makes it hard to find an unrelated donor who is a match for a certain patient. Therefore, registries are required that bring together thousands of donors to increase the chances of a successful search.

  • How is bone marrow transplanted? 

Before transplanting bone marrow, it is necessary to verify that the donor and recipient are compatible. This means that the cells of the two people are a close enough match that they can coexist indefinitely in the recipient. Normally (in 70% of cases), the transplant process is conducted through cytapheresis or peripheral blood donation. Once the donation has taken place, the product obtained is administered to the patient as if it were a transfusion. The stem cells are introduced to the recipient’s bone marrow in order to produce healthy blood cells. Sometimes (30% of cases) the donor’s bone marrow can be harvested by puncturing the iliac crests (pelvis). The most suitable method for extracting the cells will be decided based on the patient’s needs and the donor’s opinion (watch an information video in Spanish).

  • What is cytapheresis?

It is one of the two methods of extracting the donor’s haematopoietic stem cells (commonly known as bone marrow) so that they can subsequently be implanted in the recipient. Aphersis is a type of donation in which only the stem cells circulating in the blood are extracted selectively, with the rest of the blood being returned to the donor. The stem cells are separated from the blood by centrifugation in a machine to which the donor is connected with completely sterile and single-use equipment.

Stem cells are found inside bones but, if the donor is given medication known as a haematopoietic growth factor, the cells can be mobilized to the circulating blood and extracted. This haematopoietic growth factor is administered over the course of 4-5 days, after which the blood cells can be extracted by cytapheresis. On an outpatient basis, the blood taken from a vein in the arm is circulated through machines known as cell separators, which harvest the stem cells. The rest of the blood is returned to the donor through a vein in the other arm (watch an information video in Spanish).

  • What are the possible side effects of donating bone marrow? 

The only side effect of bone marrow donation by syringe aspiration is the potential pain caused at the puncture site. This pain normally fades within 48 hours and is controlled using standard painkillers. As the bone marrow is syringed under general anaesthetic, it involves the same risk as any operation performed under short-term general anaesthetic.

When the donation is made by aphersis, during the period in which haematopoietic growth factors are administered, donors may experience flu-like symptoms, such as aching bones and muscles.

  • Who decides whether my donation will be made by syringing from the iliac crests (bone marrow) or by cytapheresis?

The donor decides in view of the proposal made by the patient’s doctor. The haematology team treating the patient who needs a bone marrow transplant always notifies the donor registry conducting the search for the voluntary donor which harvesting technique they prefer. Why? Because in the case of certain diseases it is preferable for the donation to be performed one way or the other, with a view to the future medical response of the patient. In any case, with all this information at hand, the donor always has the final say.

  • Am I allowed to know whom I am giving my bone marrow to?  If not, why?

No, under Spanish law, donations are anonymous. Public knowledge of the donor’s identity and their relationship to the recipient could have negative repercussions that may cause a range of problems for the people involved.

  • Does registering on the Bone Marrow Donor Registry (REDMO), mean that I will be a donor for sure? 

No, not at all. When you register as a donor on REDMO, a blood sample is taken that is used to verify the HLA compatibility of your blood with that of the patients looking for a donor. Once you are included on REDMO and, as a consequence, on the international registry, the likelihood of compatibility and donation being performed is extremely low (approximately 1 in 4,000). If you are identified as the best donor for a recipient, the centre you have dealt with will get in contact with you.

  • Why is it so difficult for two people to be compatible? 

Our body’s immune system is a recognition and attack system that fulfils the role of distinguishing between our own tissue and foreign matter, and ensuring that our body is defended from foreign agents, infectious microorganisms, neoplastic cells and normal cells transplanted from another person. A key part of the immune system is the genetic information contained by all of our body’s cells, known as the HLA (human leukocyte antigen) system. The HLA system is primarily responsible for rejecting grafts when there is insufficient compatibility between a patient and a donor. If the HLA of the two individuals is the same, the patient’s body does not recognize the donor’s cells as foreign and so does not reject them. However, in the case of transplanting stem cells, the transplanted cells form part of the donor’s immune system and, as such, they have the capacity to reject the recipient’s body. Therefore, a high degree of HLA compatibility is required between the donor and the recipient for the donor’s healthy cells to be able to repopulate the patient’s body without being rejected or triggering rejection to eliminate the patient’s unhealthy cells. The genes of the HLA system are almost always transmitted in blocks known as haplotypes. The father and the mother contribute one haplotype each, from which the HLA genotype originates, the genetic profile of the new human being. This is why the best chance of finding a compatible donor is through brothers and sisters, as they are very likely to have inherited the same genetic material from the parents. This situation occurs in the case of one in every four patients, while the rest require an unrelated donor.

So, how do we recognize each individual’s HLA? This is achieved by studying the chains of amino acids in the genes of the HLA system present in all cells, which are known as alleles. In the case of a bone marrow transplant, we focus on the alleles referred to as A, B, C and DR, with each individual having two expressions of each of these (one from the father and one from the mother). Therefore, between the patient and the donor, we compare eight alleles. The difficulty in finding donors that share the same HLA is a result of the polymorphism of alleles. There are 5,907 different A alleles, 7,126 B alleles, 5,709 C alleles, 29 DRA alleles and 3,331 DRB alleles. So it is basically like looking for a needle in a haystack! The greater number of volunteer donors there are on the international donor registry, the greater likelihood patients have of finding an HLA that matches theirs. 

  • If I am a match with a patient in another country, will I travel to where they live? 

No, the cells required will be harvested in the nearest extraction centre to your home (equipped for such a process) and they will be sent from there to the centre where the patient is being treated.

  • Can I choose the hospital in which the donation is performed? 

No, you have to go to a specialist hospital, as not all centres conduct this procedure (or have enough experience of it). From the list of suitably equipped hospitals, you will be assigned the nearest to your home.

  • Can I be a donor for a relative, friend or specific person?

No, you cannot register as a bone marrow donor to donate to a specific person. Why not? If you are not a first-degree relative of the patient, the likelihood of compatibility is almost zero (except in cases of consanguinity). It is much more simple to find a compatible unrelated donor through REDMO from among the more than 33 million donors around the world. Besides, donation to somebody you know would breach the basic concept of anonymity.

Donation is always an anonymous act and whoever registers as a donor is willing to donate to anybody around the world who may need it, without ever knowing who it may be.

  • In the event that the donation is carried out, how long will it be before I can get back to normal?

In the case of bone marrow donations, donors are advised to take a few days (2-3) partial rest, but undertaking all types of activities. With respect to physical activities, at the beginning, they should be moderate and donors should avoid highly demanding activities. This precaution is taken to give the bone marrow time to regenerate and to allow for the low degree of anaemia that may occur after donation. In the case of peripheral blood donation, donors can get back to their normal lives practically straightway.

  • I did the HLA tests to determine whether I was compatible with a relative and now I want to register as a bone marrow donor. Can I send my HLA type?

If these tests were performed recently, you can ask for the result from the medical centre that conducted them and take these results to the corresponding donor centre as indicated by your autonomous community (link to the website) to register as a donor. If you did the tests years ago and did not keep the results, you should start the process again to register as a bone marrow donor. Find out more here:

  • If somebody decides to become a bone marrow donor, can they change their mind later?

Yes, all voluntary donors of haematopoietic progenitor cells can change their mind whenever they want. They simply have to notify the registry to this effect so that their name can be removed. Nevertheless, to avoid this situation, we really insist that anybody who registers as a bone marrow donor is extremely well informed.

  • Is there a waiting list for bone marrow transplants?

There is not a waiting list for undergoing a transplant of blood progenitor cells. When a patient requires an allogeneic transplant (from a donor) and needs an unrelated donor, an international search is carried out. If the search for a donor or for umbilical cord blood is unsuccessful and there is no possibility of a transplant, the patient must undergo a different type of medical treatment.

In the case of all patients, there is an ideal time and clinical status for undergoing the transplant. Once this period has passed, the likelihood of the treatment being successful decreases. The more donors there are, the greater the possibility of finding the ‘ideal’ donor for particular patients.

  • Do I need to have an empty stomach when registering as a bone marrow donor?

No, it is not necessary.

Questions and answers about bone marrow donation and specific illnessess

  • Can I donate bone marrow if I have had cancer?

Unfortunately not. The fact that you have had a malignant tumour, haematological or autoimmune disease means that you are not eligible to donate. The only exceptions to this rule are basal cell skin carcinoma and in-situ cervical cancer.

  • Can I donate bone marrow if I am celiac?

If celiac disease is the donor’s ONLY pathology and they are asymptomatic without treatment, they can register as a bone marrow donor. In the event of donation, it will have to be performed by syringing the iliac crests and not by cytapheresis. In all cases, it is important that the donor notifies the donor registry of their condition as a celiac so that the patient’s haematological team can assess the condition. The donor must also inform their GP and get their approval for the donation.

  • Can I donate bone marrow if I have had a stroke?

Unfortunately, you cannot register as a bone marrow donor. If you have had a stroke while registered as a donor, you must notify the bone marrow donor registry so that you can be taken off.

  • Can I donate bone marrow if I suffer from diabetes?

Yes. However, you cannot be a bone marrow donor if you have insulin-dependent diabetes, as donating may affect the donor and the patient. Diabetics who only require dietary control or oral anti-diabetic medication (tablets) can register as bone marrow donors.

  • Can I donate bone marrow if I suffer from psoriasis?

If you suffer from mild psoriasis that only requires topical treatment, you can donate bone marrow, on the condition that you duly notify the donor registry. In the event of carrying out the donation, the cells will probably be extracted by puncturing the iliac crests. People suffering from moderate or serious psoriasis that requires systematic treatment are not eligible to register as bone marrow donors.

  • Can I donate bone marrow if I have asthma?

As long as the asthma is controlled only by the use of aerosols, you can register as a donor. Otherwise, if you required systematic treatment, it is not possible.

  • Can I donate if I have had hepatitis?

It depends on the type of hepatitis. If you have had hepatitis A, you can register as a bone marrow donor. If you have had hepatitis B or C, or you have lived with people that have had it, you cannot. People who live with sufferers of hepatitis B or C cannot donate until four months have passed since the end of the cohabitation.

  • Can I donate if I have recently undergone an operation?

At least four weeks must have passed since the procedure in the case of minor surgery (not requiring general anaesthetic nor mechanical ventilation) and four months in the case of major surgery (requiring general anaesthetic and mechanical ventilation).

Questions and answers about bone marrow donations and specific situation

  • Can I donate bone marrow if I have had a tattoo or piercing?

As long as it is over 4 months since the procedure, you can register as a bone marrow donor or, in the case of people already registered, the donation can be carried out if the occasion arises.

  • Can I donate bone marrow if I am breastfeeding?

Yes, you can register without any problem during breastfeeding. If the donor is registered and the donation is to be carried out, they will have to suspend breastfeeding for at least the days on which the donor is given growth factors (4-5 days) or anaesthetic (1-2 days).

  • Can I donate bone marrow if I am pregnant?

Yes, you can register without any problems and at no risk to the pregnancy. If you are already registered and the time comes to conduct the donation, you cannot do so during your pregnancy and for six months after giving birth. It is important to notify the registry of bone marrow donors to this effect so that you can be taken off the register temporarily.

  • Can I register as a bone marrow donor if I lived in the United Kingdom between 1980 and 1996?

If you lived in the United Kingdom (England, Scotland, Wales, Northern Ireland, Isle of Man) during this period for more than a year, you cannot donate. Since 2001, the Spanish Ministry of Health has implemented this exclusion criterion for blood and bone marrow donation as an extreme precautionary measure, basically for the preparation of blood products. The aim of the measure is to prevent the very slight risk of transmitting the variant of Creutzfeldt–Jakob disease or 'mad cow disease' to Spanish recipients of blood transplants. You may also not register as a bone marrow donor if you have received a blood transfusion in this country.

  • I am a Spanish resident and I am registered as a bone marrow donor here through REDMO but I am going to live abroad permanently. What do I have to do?

First of all, you have to notify us by email ( or telephone (93 414 55 66) so that we can take you off the register. If you will be living abroad on a short-term basis (under two years), we can take you off the register temporarily and, when you return to Spain, we can put you back on. If you are planning to live abroad on a permanent basis and you are moving to a country with a similar registry, you can ask us to send your HLA type and transfer request to the country. In the event that the country you are moving to does not have a similar type of registry, your only option is to unregister from REDMO.

  • Can I donate bone marrow if I am a smoker?

Yes, but we recommend that you give up as it is harmful to your health.

  • Can I register as a bone marrow donor if I am 16 years old and have my parents’ authorization?

We are afraid not. Under international regulations, only people aged 18 and above can register as bone marrow donors.

Webpage updated 02/09/2023 17:39:10