<unk>  cell anaemia<unk>  cells in human blood - both normal red blood cells and<unk> -shaped cells are present. Normal blood cells next to a<unk>  blood cell, coloured scanning electron microscope image Signs of<unk>  usually begin in early childhood. The severity of symptoms can vary from person to person.<unk>  may lead to various acute and chronic complications, several of which have a high mortality rate.<unk>  cell crisis The terms<unk>  cell crisis" or "sickling crisis" may be used to describe several independent acute conditions occurring in patients with<unk> , which results in anaemia and crises that could be of many types, including the vaso-occlusive crisis, aplastic crisis, splenic sequestration crisis, haemolytic crisis, and others. Most episodes of<unk>  cell crises last between five and seven days. "Although infection, dehydration, and acidosis (all of which favor<unk> ng) can act as triggers, in most instances, no predisposing cause is identified." Vaso-occlusive crisis The vaso-occlusive crisis is caused by<unk> -shaped red blood cells that obstruct capillaries and restrict blood flow to an organ, resulting in ischaemia, pain, necrosis, and often organ damage. The frequency, severity, and duration of these crises vary considerably. Painful crises are treated with hydration, analgesics, and blood transfusion; pain management requires opioid drug administration at regular intervals until the crisis has settled. For milder crises, a subgroup of patients manages on nonsteroidal anti-inflammatory drugs such as diclofenac or naproxen. For more severe crises, most patients require inpatient management for intravenous opioids; patient-controlled analgesia devices are commonly used in this setting. Vaso-occlusive crisis involving organs such as the penis or lungs are considered an emergency and treated with red blood cell transfusions. Incentive spirometry, a technique to encourage deep breathing to minimise the development of atelectasis, is recommended. Splenic sequestration crisis The spleen is frequently affected in<unk> , as the<unk> -shaped red blood cells cause narrowing of blood vessels and reduced function in clearing the defective cells. It is usually infarcted before the end of childhood in individuals suffering from<unk>  cell anaemia. This spleen damage increases the risk of infection from encapsulated organisms; preventive antibiotics and vaccinations are recommended for those lacking proper spleen function. Splenic sequestration crises are acute, painful enlargements of the spleen, caused by intrasplenic trapping of red cells and resulting in a precipitous fall in haemoglobin levels with the potential for hypovolemic shock. Sequestration crises are considered an emergency. If not treated, patients may die within 1–2 hours due to circulatory failure. Management is supportive, sometimes with blood transfusion. These crises are transient; they continue for 3–4 hours and may last for one day. Acute chest syndrome Acute chest syndrome is defined by at least two of these signs or symptoms: chest pain, fever, pulmonary infiltrate or focal abnormality, respiratory symptoms, or hypoxemia. It is the second-most common complication and it accounts for about 25% of deaths in patients with<unk> . Most cases present with vaso-occlusive crises, and then develop acute chest syndrome. Nevertheless, about 80% of people have vaso-occlusive crises during acute chest syndrome. Aplastic crisis Aplastic crises are instances of an acute worsening of the patient's baseline anaemia, producing pale appearance, fast heart rate, and fatigue. This crisis is normally triggered by parvovirus B19, which directly affects production of red blood cells by invading the red cell precursors and multiplying in and destroying them. Parvovirus infection almost completely prevents red blood cell production for two to three days. In normal individuals, this is of little consequence, but the shortened red cell life of<unk>  patients results in an abrupt, life-threatening situation. Reticulocyte counts drop dramatically during the<unk>  (causing reticulocytopenia), and the rapid turnover of red cells leads to the drop in haemoglobin. This crisis takes 4 to 7 days to disappear. Most patients can be managed supportively; some need a blood transfusion. Haemolytic crisis Haemolytic crises are acute accelerated drops in haemoglobin level. The red blood cells break down at a faster rate. This is particularly common in people with coexistent G6PD deficiency. Management is supportive, sometimes with blood transfusions. Other One of the earliest clinical manifestations is dactylitis, presenting as early as six months of age, and may occur in children with<unk>  cell trait. The crisis can last up to a month. Given that pneumonia and<unk> ng in the lung can both produce symptoms of acute chest syndrome, the patient is treated for both conditions. It can be triggered by painful crisis, respiratory infection, bone-marrow embolisation, or possibly by atelectasis, opiate administration, or surgery. Hematopoietic ulcers may also occur. Complications<unk>  cell anaemia can lead to various complications, including: * Increased risk of severe bacterial infections is due to loss of functioning spleen tissue (and comparable to the risk of infections after having the spleen removed surgically). These infections are typically caused by encapsulated organisms such as Streptococcus pneumoniae and Haemophilus influenzae. Daily penicillin prophylaxis is the most commonly used treatment during childhood, with some haematologists continuing treatment indefinitely. Patients benefit today from routine vaccination for S. pneumoniae. * Stroke, which can result from a progressive narrowing of blood vessels, prevents oxygen from reaching the brain. Cerebral infarction occurs in children and cerebral haemorrhage in adults. * Silent stroke causes no immediate symptoms, but is associated with damage to the brain. Silent stroke is probably five times as common as symptomatic stroke. About 10–15% of children with<unk>  suffer strokes, with silent strokes predominating in the younger patients. * Cholelithiasis (gallstones) and cholecystitis may result from excessive bilirubin production and precipitation due to prolonged haemolysis. * Avascular necrosis (aseptic bone necrosis) of the hip and other major joints may occur as a result of ischaemia. * Decreased immune reactions due to hyposplenism (malfunctioning of the spleen) * Priapism and infarction of the penis * Osteomyelitis (bacterial bone infection), the most common cause of osteomyelitis in<unk>  is Salmonella (especially the atypical serotypes Salmonella typhimurium, Salmonella enteritidis, Salmonella choleraesuis, and Salmonella paratyphi B), followed by Staphylococcus aureus and Gram-negative enteric bacilli perhaps because intravascular<unk> ng of the bowel leads to patchy ischaemic infarction. * Acute papillary necrosis in the kidneys * Leg ulcers * In eyes, background retinopathy, proliferative retinopathy, vitreous haemorrhages, and retinal detachments can result in blindness. Regular annual eye checks are recommended. * During pregnancy, intrauterine growth restriction, spontaneous abortion, and pre-eclampsia * Chronic pain: Even in the absence of acute vaso-occlusive pain, many patients have unreported chronic pain. * Pulmonary hypertension (increased pressure on the pulmonary artery) can lead to strain on the right ventricle and a risk of heart failure; typical symptoms are shortness of breath, decreased exercise tolerance, and episodes of syncope. 21% of children and 30% of adults have evidence of pulmonary hypertension when tested; this is associated with reduced walking distance and increased mortality. * Cardiomyopathy and left ventricular diastolic dysfunction caused by fibrosis or scarring of cardiac tissues. This also contributes to pulmonary hypertension, decreased exercise capacity, and arrhythmias. * Chronic kidney failure due to<unk> -cell nephropathy manifests itself with hypertension, protein loss in the urine, loss of red blood cells in urine and worsened anaemia. If it progresses to end-stage kidney failure, it carries a poor prognosis.
Sickle cell disease
Glucose-6-phosphate dehydrogenase deficiency
Sickle cell trait
Avascular necrosis
Primary hyperoxaluria
Sick cell syndrome
Thalassemia
Hawkinsinuria