Transient aplastic crisis
Transient aplastic crisis
Description, Causes and Risk Factors:
Transient aplastic crisis (TAC) usually lasts for 7-10 days in chronic hereditary or acquired hemolytic anemias of varied etiologies in children. Human parvovirus B-19 (HPV) infection, which is cytotoxic to erythropoietic progenitor cells, has been associated with development of transient aplastic crisis.
An aplastic crisis usually occurs in children under the age of 16 years. It occurs in the general population, but can only be noticed in those people with chronic anemias (such as sickle cell anemia).
Transient aplastic phase in hemolytic anemia has been described in congenital and acquired hemolytic conditions such as hereditary spherocytosis, sickle cell anemia, thalassemia, pyruvate kinase deficiency, autoimmune hemolytic anemia and congenital dyserythropoietic anemia type II. It may follow the development of nonspecific viral illnesses such as HPV B-19 infection which predominantly occurs in children between 4 to 10 years of age. However, aplastic phase in hemolytic anemia has been described in adults. The presence of anti-HPV of IgM class denotes a recent infection and these antibodies may be detected in some patients even up to 10-12 months after the infection. Virus primarily affects the erythroblasts but may involve other cell lines resulting in leukopenia and/or thrombocytopenia. Other viruses such as mumps, non A-non-B, HIV, EB virus and infections such as mycoplasma, Salmonella, streptococcus have been implicated in the causation of aplastic crisis. The impact of infection is more apparent in conditions of ineffective erythropoiesis. In healthy persons erythroblastopenic effect of infection passes off without its recognition whereas in hemolytic anemia the effect of any of these infections leading to erythroblastopenia of marrow becomes evident by development of severe anemia.
Supportive treatment with packed red cell is the mainstay of treatment. The possibility of the immunization against HPV in children with chronic hemolytic anemia will be of interest as children with hemolytic anemia will not develop this complication following an effective immunization.
Symptoms may include:
Anemia (low blood count).
Recent upper respiratory infection.
Passing out (fainting).
The diagnosis of transient aplastic crisis due to parvovirus B19 is often presumptive, based on a falling hemoglobin value and a low reticulocyte count in a patient with a hemolytic anemia. Specific DNA probes allow definitive diagnosis by PCR since the viremia is robust. A rising IgM antibody to the virus is another means of diagnosing parvovirus B19 infection.
Researchers tested B19 parvovirus DNA/viral particles and specific anti-B19 parvovirus IgM and IgG antibodies. B19 parvovirus DNA/viral particles were detected in 11 (21%) of 53 patients with TAC. Specific anti-B19 parvovirus IgM antibodies were detected in 34 (64%) of the 53 patients. Overall, 36 (68%) of 53 patients with TAC had evidence of acute B19 parvovirus infection as shown by the detection of B19 DNA parvovirus and/or specific anti-B19 parvovirus IgM antibodies in acute-phase serum. Follow-up serologic studies in eight patients with acute infection revealed disappearance of B19 parvovirus DNA/viral particles and anti-B19 parvovirus IgM antibodies and persistence of anti-B19 parvovirus IgG antibodies for up to 3 1/2 years after the diagnosis of acute B19 parvovirus infection. No patient had evidence of recurrent or chronic B19 parvovirus infection.
Transient aplastic crisis usually is self-limiting and requires only supportive measures. Rare patients require more than a single transfusion to bridge the gap between marrow suppression and recovery. The fact that the BFU-E's (Erythroid burst-forming units) are not suppressed by the virus means that the bone marrow is poised for a rapid response once the virus is tamed. Rare patients will need immunoglobulin treatment, which is dramatically effective in reversing the aplasia. Immunoglobulin concentrate is the treatment of choice and is delivered as 0.4 g/kg/day for 5 days.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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