Anemia
Revisado por pares por Dr Toni Hazell, MRCGPÚltima actualización por Dr Hayley Willacy, FRCGP Última actualización 13 Feb 2023
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En esta serie:Dietas adecuadas para personas con anemiaDeficiencia de ácido fólicoAnemia por deficiencia de hierroMacrocitosis y anemia macrocíticaDeficiencia de vitamina B12 y anemia perniciosa
La anemia significa que tienes menos glóbulos rojos de lo normal o que tienes menos hemoglobina de lo normal en cada glóbulo rojo. En cualquiera de los casos, una cantidad reducida de oxígeno se transporta por la sangre.
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Anaemia types and causes
Anemia por deficiencia de hierro
Lack of iron is the most common type of anaemia in the UK. This is called iron-deficiency anaemia. If you eat a normal balanced diet, it usually contains enough iron.
See the separate leaflet called Diets Suitable for People with Anaemia.
See also the separate leaflet called Iron-deficiency Anaemia.
Vitamin deficiency anaemia
Lack of certain vitamins such as folic acid and vitamin B12 can cause anaemia.
Vea los folletos separados llamados Folic Acid Deficiency Anaemia y Vitamin B12 Deficiency and Pernicious Anaemia.
Haemolytic anaemia
Normally, red blood cells live for about 120 days before they are broken down by the body. In haemolytic anaemia they live for a much shorter time. The anaemia occurs because your bone marrow cannot produce enough new red blood cells to replace the ones that are being broken down too quickly.
There are several reasons that this happens. Genetic conditions where there is an abnormality in the red cell membrane such as esferocitosis hereditaria, or elliptocytosis. Conditions where there are haemoglobin abnormalities such as sickle cell anaemia o thalassaemia - these are discussed below. And problems with the chemicals (or enzymes) that help the blood cell do its job, such as G6PD deficiency and pyruvate kinase deficiency.
Another set of conditions may arise from your immune system attacking your own red blood cells, such as autoimmune haemolytic anaemia, blood transfusion reactions and other autoimmune conditions such as lupus eritematoso sistémico.
Some medications may cause haemolysis, such as penicillin. You can also have haemolysis caused by mechanical heart valves, malaria and liver disease. There is a wide variety of reasons you might develop haemolytic anaemia.
Talasemia
Talasemia is an inherited condition affecting the blood. There are different types, which vary from a mild condition with no symptoms, to a serious or life-threatening condition. For the more severe forms of thalassaemia, modern treatment gives a good outlook, but lifelong monitoring and treatment are needed. Good treatment is important to prevent complications developing.
Sickle cell anaemia
Enfermedad de células falciformes (SCD) is a serious, inherited condition affecting the blood and various organs in the body. It affects the red blood cells, causing episodes of 'sickling', which produce episodes of pain and other symptoms. In between episodes of sickling, people with SCD are normally well. Long-term complications can occur. Good treatment, started early in life, can prevent complications. So, early diagnosis and specialist treatment are advised for SCD. Sickle cell trait is not the same as sickle cell enfermedad.
Aplastic anaemia
Aplastic anaemia is a group of disorders that cause bone marrow failure. Most often no cause is found but there are also some inherited bone marrow failure syndromes. Sometimes a trigger can cause aplastic anaemia, and examples of those include drugs, viruses and toxins.
Anaemia of chronic disease
Some long-term illnesses may lead to anaemia. These include enfermedad renal crónica, tuberculosis, insuficiencia cardíaca crónica and malnutrition. We don't fully understand why the anaemia happens but it may be partly due to reduced production of new red blood cells. Sometimes the anaemia is mild and doesn't need treatment but there are several treatment options available as well as treating the underlying disease.
Risk factors for anaemia
Volver al contenidoSome conditions that cause anaemia are inherited, so having a close family member who has that condition will increase your risk.
Some medications may have an effect on the bone marrow, or on red blood cells, and cause anaemia.
The following are some situations that may have a risk of developing a lack of iron and result in iron-deficiency anaemia:
Pregnancy or childhood growth spurts. These are times when you need more iron than usual. The amount of iron that you eat during these times may not be enough.
Heavy menstrual periods. The amount of iron that you eat may not be enough to replace the amount that you lose from heavy periods.
Poor absorption of iron. This may occur with some gut (intestinal) diseases that mean the gut is not as effective at absorbing iron - for example, coeliac disease y enfermedad de Crohn.
Bleeding from the gut (intestines). Some conditions of the gut can bleed enough to cause anaemia. You may not be aware of losing blood this way. The bleeding may be slow or intermittent and you can pass blood out with your stools (faeces) without noticing.
If you eat a poor or restricted diet. Your diet may not contain enough iron.
If you have a chronic condition, such as heart failure or kidney disease, you are also at risk.
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Anaemia symptoms
Volver al contenidoCommon symptoms of anaemia are due to the reduced amount of oxygen being carried in the body.
These include tiredness, having little energy (lethargy), feeling faint and developing shortness of breath.
Less common symptoms include headaches, a 'thumping heart' (palpitaciones), altered taste, and ringing in the ears (tinnitus).
You may look pale. You may develop sore areas at the corners of your mouth.
You may have spoon-shaped nails, a sore tongue or hair loss.
Some people may have difficulty swallowing, hair loss o restless legs syndrome.
Various other symptoms may develop, depending on the underlying cause of the anaemia.
Anaemia diagnosis
Volver al contenidoA simple blood test can measure the amount of haemoglobin in your blood and count the number of red blood cells per millilitre (ml). Although this test can confirm that you are anaemic, it does not identify the cause of your anaemia.
Sometimes the underlying cause is obvious. For example, pregnant women and women who have menstruaciones abundantes may commonly develop iron-deficient anaemia.. In these situations, no further tests may be needed and treatment with iron supplements may be advised. However, the cause of the anaemia may not be clear and so further tests may be advised.
Some causes of anaemia are more serious than others and it is important to find the reason for anaemia.
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Anaemia treatment
Volver al contenidoThe treatment of anaemia depends on the underlying cause. For people with iron-deficiency anaemia this may simply be iron tablets. People who do not respond well to medication may be offered a blood transfusion if they are having severe symptoms.
Those with B12 deficiency will need inyecciones de vitamina B12. The injections are usually given frequently at the start of treatment. This quickly builds up the body's store of vitamin B12. Vitamin B12 is stored in the liver. Once a store of vitamin B12 has built up, this can supply the body's needs for several months. An injection is then only usually needed every two to three months to top up the supply.
Folic acid deficiency is treated with tablets in addition to a folate-rich diet. The tablets can be stopped if your diet improves. You may need to continue with treatment if a poor diet was not the cause of folic acid deficiency.
Currently there is no cure for sickle cell disease (SCD) other than a trasplante de células madre, so lifelong treatment and monitoring are needed. There are a number of different treatments which help to prevent sickling episodes, or prevent related problems such as infection. Sometimes you might need a blood transfusion. For others it may be a course of vitamins or other more complex treatments.
Anaemia of chronic disease cannot be treated by supplements or tablets. Treatments that stimulate the bone marrow to produce more red blood cells are needed.
Anaemia outlook
Volver al contenidoFor the most common types of anaemia, (iron deficiency, B12 or folic acid deficiency) there are relatively simple treatments and these should keep you well. For the more complex types of anaemia (sickle cell, thalassaemia, aplastic anaemia) treatment is more complex. For example, sickle cell disease may shorten life. Without treatment, people with SCD may die in childhood, from problems such as infection. Good treatment makes a great difference. Improvements in treatment mean that life expectancy has increased. However, even with modern treatment, SCD can still cause serious or life-threatening problems.
The outlook associated with the anaemia of chronic disease, is more about the severity of the underlying condition.
Selecciones del paciente para Anemia

Alergias, sangre y sistema inmunológico
Macrocitosis y anemia macrocítica
La macrocytosis se refiere a glóbulos rojos que son más grandes de lo normal. No causa síntomas por sí misma.
por la Dra. Philippa Vincent, MRCGP

Alergias, sangre y sistema inmunológico
Anemia por deficiencia de hierro
Iron-deficiency anaemia is a common type of anaemia that is caused by a lack of iron. Symptoms include pale skin and lack of energy. A low level of iron, leading to anaemia, can result from various causes. Some are more serious than others.
por la Dra. Rachel Hudson, MRCGP
Lecturas adicionales y referencias
- UK Thalassaemia Society
- Sickle Cell Society
- Anaemia - iron deficiency; NICE CKS, agosto 2024 (acceso solo en el Reino Unido)
- Newhall DA, Oliver R, Lugthart S; Anaemia: A disease or symptom. Neth J Med. 2020 Apr;78(3):104-110.
- Palmer D, Seviar D; How to approach haemolysis: Haemolytic anaemia for the general physician. Clin Med (Lond). 2022 May;22(3):210-213. doi: 10.7861/clinmed.2022-0142.
- Madu AJ, Ughasoro MD; Anaemia of Chronic Disease: An In-Depth Review. Med Princ Pract. 2017;26(1):1-9. doi: 10.1159/000452104. Epub 2016 Sep 28.
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Historial del artículo
La información en esta página está escrita y revisada por pares por clínicos calificados.
Próxima revisión: 12 Feb 2028
13 Feb 2023 | Última versión

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