Sickle cell anemia (technical term: drepanocytosis) is a hereditary disease of red blood cells. A distinction is made between a severe homozygous and a mild heterozygous form. Because heterozygous sickle cell anemia confers a degree of resistance to malaria, it is prevalent primarily in malaria risk areas (Africa, Asia, and the Mediterranean region).
What is sickle cell anemia?
Sickle cell anemia is one of the hemoglobinopathies (disorders of the red blood pigment hemoglobin). Hemoglobin is a complicated protein composed of 4 subunits that gives red blood cells (erythrocytes) their color and binds oxygen for transport throughout the body. Hemoglobin (HbS), which is altered in sickle cell anemia, tends to crystallize in the absence of oxygen. As a result, the erythrocytes become sickle-cell shaped and clog vessels, perish or are broken down prematurely. Sickle cell anemia is therefore characterized by hemolytic anemia and circulatory disorders.
Causes
Sickle cell anemia is caused by a gene mutation that results in the replacement of a single amino acid in the amino acid sequence of the hemoglobin-β subunits. The disease is inherited in an autosomal-codominant manner. Heterozygous sufferers have one healthy and one diseased allele; in them, only about 1 percent of the hemoglobin is altered. Homozygous patients with two mutated alleles have only abnormal hemoglobin, which leads to a much more severe course of the disease. Even in the healthy organism, there is a physiological lack of oxygen in small vessels, which causes the healthy hemoglobin to release its oxygen here. In homozygous sickle cell anemia, even this physiologically low partial pressure of oxygen leads to deformation of the erythrocytes. They clog the vessels and tend to disintegrate. The hemoglobin released in this process binds nitric oxide – an important vasodilator. The vessels therefore not only become clogged, but also constrict. Due to the occlusion of many small end arteries, sickle cell anemia results in circulatory disorders and damage to various organ systems.
Symptoms, complaints, and signs
The symptoms of sickle cell anemia can vary in severity depending on whether the affected person is a homozygous or heterozygous carrier of the responsible gene mutation. In heterozygous carriers, there are usually generally no symptoms. However, hemolysis may occasionally occur. In this case, many red blood cells are suddenly broken down, which can put a great strain on the kidneys in particular and leads to a temporary lack of oxygen. This form of hemolysis can be life-threatening. In heterozygous carriers, such a decay of red blood cells follows as a response to oxygen deficiency or certain drugs. Homozygous carriers, on the other hand, show the first symptoms only a few months after birth. Severe attacks of pain may occur as a result of a lack of oxygen supply. Blood vessels also become clogged more frequently, which can lead to small and large infarcts. Tissue death occasionally occurs in the parts of the body that are not supplied with oxygen. Bone pain is very common. Those suffering from sickle cell anemia also have an increased susceptibility to infections and often complain of fever. The tendency to jaundice is greatly increased, which is due to the increased breakdown of destroyed erythrocytes. In addition, all the symptoms of anemia appear. This results in pallor, pale mucous membranes, difficulty concentrating, a feeling of weakness and, in some cases, shortness of breath.
Diagnosis and course
In the first months of life, each person produces a special fetal hemoglobin that is not affected by the genetic defect of sickle cell anemia. Therefore, the disease does not become apparent until 6 months of age, when adult hemoglobin comes into play. In childhood, it is predominantly the homozygous patients who stand out: they suffer painful hemolytic crises early on. These include hemolytic anemia with pallor, jaundice, and weakness, as well as circulatory disturbances and multiple small organ infarcts, typically in the brain and eye, spleen, lung, kidney, and heart, and in muscle and bone. Skeletal maturity is delayed. Painful permanent erection (priapism) is also a typical symptom. The diagnosis of sickle cell anemia is confirmed by laboratory diagnostics, especially by hemoglobin gel electrophoresis.A genetic test differentiates between homozygous and heterozygous disease. Only half of homozygous patients reach the age of 30. Because of the pre-damaged lungs, lung infections are the most frequent cause of death. In contrast to the severe form of the disease, heterozygous sickle cell anemia can remain inconspicuous for a long time. In this case, the first hemolytic crisis may not occur until nonphysiologic oxygen deprivation occurs, such as during extreme exercise or altitude exposure.
Complications
Sickle cell anemia can result in complications, sometimes with a severe course. The effects are seen when vessels in different parts of the body become blocked at the sickle cells. Doctors then also speak of a sickle cell crisis. If small vessels in the legs are blocked by sickle cell anemia, there is a risk of skin ulcers developing on the legs. Seizures are considered a neurological complication. In severe cases, cerebral hemorrhages or a slipping of the patient into coma are also possible. This is due to blockages within the brain that require immediate treatment. Another consequence of sickle cell anemia is the formation of gallstones. They are not the result of vascular blockage, but are caused by the decay of red blood cells (erythrocytes). One of the by-products of this decay is bilirubin. If the bilirubin level in the blood is increased, there is an increased risk of gallstones forming, which are also known as pigment stones. In the male sex, priapism is sometimes seen in sickle cell anemia. This is a painful and permanent erection. It occurs due to the blockage of blood vessels inside the penis. Without treatment, priapism can result in erectile dysfunction. Blindness is a feared complication of sickle cell anemia. It is caused by blockages of the vessels responsible for supplying the eyes. This threatens damage to the retina.
When should you see a doctor?
Only medical treatment of this disease can prevent further complications and discomfort. Therefore, a doctor should be consulted at the first signs and symptoms of sickle cell anemia. A doctor should be consulted if the patient suffers from a permanent lack of oxygen. This often results in severe fatigue or confusion, and the affected person is also sluggish and no longer actively participates in everyday life. Furthermore, severe pain in the head or bones may indicate sickle cell anemia and must also be treated by a physician. Patients suffer from an increased susceptibility to infections and also from severe pallor or high fever. If sickle cell anemia is not treated, the patient’s life expectancy is significantly reduced. Sickle cell anemia can be recognized and treated by a general practitioner. A visit to a specialist may also be necessary for treatment. However, the further course of sickle cell anemia also depends greatly on the exact nature of the disease.
Treatment and therapy
A causal therapy for sickle cell anemia does not (yet) exist. The only hope for a cure is bone marrow transplantation – but these are used only in exceptional cases and are still associated with relatively high mortality. Routine treatment of sickle cell anemia focuses on delay and relief of symptoms. Especially in pain crises, patients need to be provided with analgesics. In cases of acute hemoglobin drop, partial blood exchange transfusions may be useful. Often in sickle cell anemia, the spleen has regressed and is not sufficiently functional; patients then require careful vaccination protection, e.g., against pneumococci. However, if the spleen does not regress, it may also enlarge pathologically (splenomegaly), contributing to worsening anemia and requiring splenectomy (removal of the spleen). In any case, patients with sickle cell anemia should attend regular routine outpatient checkups, even outside of crises.
Prevention
Because sickle cell anemia is a hereditary genetic defect, there is no prevention against the disease itself.However, heterozygous patients can contribute to a milder course by avoiding oxygen deprivation (such as altitude exposure or exercise), ensuring careful vaccination protection, and seeking regular medical checkups.
Follow-up care
Sickle cell anemia is not considered curable. The focus of follow-up care for patients with sickle cell anemia is patient education, patient counseling (lifestyle), infection prophylaxis and vaccinations, and routine diagnostic testing. The object of patient education is to inform the patient about the disease itself. He must learn that sickle cell anemia can lead to life-threatening symptoms. The warning signs of acutely threatening complications (e.g. sepsis) should be present to the patient and should lead to immediate presentation to a physician. It is known to physicians that in patients with sickle cell anemia, an episode can be triggered by dehydration, hypothermia, hypoxia, acidosis, and infection. Patient counseling is therefore aimed at making the patient aware of these five factors in his or her lifestyle so that he or she avoids them as much as possible. The period between relapses can thus be extended. In addition to general hygiene measures, patients with sickle cell anemia are prescribed daily penicillin as a prophylactic against infection. In addition, to protect against infection, every patient with sickle cell anemia should receive at least one vaccination with 13-valent pneumococcal conjugate vaccine during follow-up. For routine diagnostics, it is recommended that patients with sickle cell anemia present to a specialized center at least once a year. There, the blood count, blood pressure, pulse rate, liver and kidney values, urine status, and protein excretion should be examined clinically. Likewise, echocardiography should be performed.
This is what you can do yourself
The condition is usually noticed within the first few months or years of life. By nature, the patient cannot sufficiently help himself or obtain improvement of his situation at this age. Therefore, relatives and guardians have a responsibility to provide adequate care for the offspring and to work closely with the attending physician. To support blood circulation, food intake should be optimized. Specific foods can be used to achieve an intake of nutrients that stimulate blood formation. In addition, an oxygen-rich environment is particularly important for the infant. Rooms should be adequately ventilated and walks outdoors help to supply sufficient oxygen. Although these measures do not cure sickle cell anemia, they can positively support the child’s organism. The child should not be in an environment where nicotine or other toxins are present in the air. Situations of overexertion and heavy load should also be avoided. To protect against infections, care should be taken to minimize contagion. Leisure activities or sports activities should also be adapted to the needs of the organism. Sufficient rest and sparing are important to avoid putting the immune system under unnecessary strain.
