عدد الرسائل : 4042
العمل/الترفيه : طبيب أختصاصي طب الأطفال وحديثي الولادة
المزاج : الحمد لله جيد
تاريخ التسجيل : 15/09/2008
|موضوع: Approach to the Child with Anemia الإثنين أكتوبر 20, 2008 3:14 am|| |
Approach to the Child with Anemia
Anemia is a relatively common finding, and identifying the cause is important. Even though anemia in childhood has many causes, the correct diagnosis can usually be established with relatively little laboratory cost.
Frequently the cause is identified with a careful history. The possibility of nutritional causes should be addressed by inquiry about dietary intake; growth and development; and symptoms of chronic disease, malabsorption, or blood loss. Hemolytic disease may be associated with a history of jaundice (including neonatal jaundice) or by a family history of anemia, jaundice, gallbladder disease, splenomegaly, or splenectomy. The child's ethnic background may suggest the possibility of certain hemoglobinopathies or of deficiencies of red cell enzymes such as glucose-6-phosphate dehydrogenase (G6PD). The review of systems may reveal clues to a previously unsuspected systemic disease associated with anemia. The patient's age is important because some causes of anemia are age-related. For example, patients with iron-deficiency anemia and globin disorders present more commonly at ages 6–36 months than at other times in life.
The physical examination may also reveal clues to the cause of anemia. Poor growth may suggest chronic disease or hypothyroidism. Congenital anomalies may be associated with constitutional aplastic anemia (Fanconi anemia) or with congenital hypoplastic anemia (Diamond–Blackfan anemia). Other disorders may be suggested by the findings of petechiae or purpura (leukemia, aplastic anemia, hemolytic–uremic syndrome), jaundice (hemolysis or liver disease), generalized lymphadenopathy (leukemia, juvenile rheumatoid arthritis, HIV infection), splenomegaly (leukemia, sickle hemoglobinopathy syndromes, hereditary spherocytosis, liver disease, hypersplenism), or evidence of chronic or recurrent infections.
The initial laboratory evaluation of the anemic child consists of a complete blood count (CBC) with differential and platelet count, review of the peripheral blood smear, and a reticulocyte count. The algorithm in Figure 27–1 uses limited laboratory information, together with the history and physical examination, to reach a specific diagnosis or to focus additional laboratory investigations on a limited diagnostic category (eg, microcytic anemia, bone marrow failure, pure red cell aplasia, or hemolytic disease). This diagnostic scheme depends principally on the MCV to determine whether the anemia is microcytic, normocytic, or macrocytic, according to the percentile curves of Dallman and Siimes (Figure 27–2).
Although the incidence of iron deficiency in the United States has decreased significantly with improvements in infant nutrition, it remains an important cause of microcytic anemia, especially at ages 6–24 months. A trial of therapeutic iron is appropriate in such children, provided the dietary history is compatible with iron deficiency and the physical examination or CBC count does not suggest an alternative cause for the anemia. If this is not the case or if a trial of therapeutic iron fails to correct the anemia and microcytosis, further laboratory evaluation is warranted.
Another key element of Figure 27–1 is the use of both the reticulocyte count and the peripheral blood smear to determine whether a normocytic or macrocytic anemia is due to hemolysis. Typically hemolytic disease is associated with an elevated reticulocyte count, but some children with chronic hemolysis initially present during a period of virus-induced aplasia when the reticulocyte count is not elevated. Thus, review of the peripheral blood smear for evidence of hemolysis (eg, spherocytes, red cell fragmentation, sickle forms) is important in the evaluation of children with normocytic anemias and low reticulocyte counts. When hemolysis is suggested, the correct diagnosis may be suspected by specific abnormalities of red cell morphology or by clues from the history or physical examination. Autoimmune hemolysis is usually excluded by direct antiglobulin testing. Review of blood counts and the peripheral blood smears of the mother and father may suggest genetic disorders such as hereditary spherocytosis. Children with normocytic or macrocytic anemias, with relatively low reticulocyte counts and no evidence of hemolysis on the blood smear, usually have anemias caused by inadequate erythropoiesis in the bone marrow. The presence of neutropenia or thrombocytopenia in such children suggests the possibility of aplastic anemia, malignancy, or severe folate/vitamin B12 deficiency, and usually dictates examination of the bone marrow.
Pure red cell aplasia may be congenital (Diamond–Blackfan anemia), acquired and transient (transient erythroblastopenia of childhood), a manifestation of a systemic disease such as renal disease or hypothyroidism, or due to malnutrition or mild deficiencies of folate or vitamin B12.
[center]Hermiston ML: A practical approach to the evaluation of the anemic child. Pediatr Clin North Am 2002;49:877. [PMID: 12430617]
Pure Red Cell Aplasia
Infants and children with normocytic or macrocytic anemia, a low reticulocyte count, and normal or elevated numbers of neutrophils and platelets should be suspected of having pure red cell aplasia. Examination of the peripheral blood smear in such cases is important because signs of hemolytic disease suggest chronic hemolysis complicated by an aplastic crisis due to parvovirus infection. Appreciation of this phenomenon is important because chronic hemolytic disease may not be diagnosed until the anemia is exacerbated by an episode of red cell aplasia and subsequent rapidly falling hemoglobin level. In such cases, cardiovascular compromise and congestive heart failure may develop quickly.
Congenital Hypoplastic Anemia (Diamond–Blackfan Anemia)
Essentials of Diagnosis & Typical Features
Bone marrow with erythroid hypoplasia.
Short stature or congenital
anomalies in one-third of patients.
Diamond–Blackfan anemia is a relatively rare cause of anemia that usually presents in infancy or early childhood. Early diagnosis is important because treatment with corticosteroids results in increased erythropoiesis in about two-thirds of patients, thus avoiding the difficulties and complications of long-term chronic transfusion therapy. The cause is unclear; both autosomal dominant and autosomal recessive modes of inheritance occur.
Symptoms and Signs
Signs and symptoms are generally those of chronic anemia, such as pallor; congestive heart failure sometimes follows. Jaundice, splenomegaly, or other evidence of hemolysis is usually absent. Short stature or other congenital anomalies are present in one-third of patients. A wide variety of anomalies have been described; those affecting the head, face, and thumbs are the most common.
Diamond–Blackfan anemia is characterized by severe macrocytic anemia and marked reticulocytopenia. The neutrophil count is usually normal or slightly decreased, and the platelet count is normal or elevated. The bone marrow usually shows a marked decrease in erythroid precursors but is otherwise normal. In older children, fetal hemoglobin levels are usually increased and there is evidence of persistent fetal erythropoiesis, such as the presence of the i antigen on erythrocytes. In addition, the level of adenosine deaminase in erythrocytes is elevated.
The principal differential diagnosis is transient erythroblastopenia of childhood. Children with Diamond–Blackfan anemia generally present at an earlier age, often have macrocytosis, and have evidence of fetal erythropoiesis and an elevated level of red cell adenosine deaminase. In addition, short stature and congenital anomalies, are not associated with transient erythroblastopenia. Lastly, transient erythroblastopenia of childhood usually resolves within 6–8 weeks of diagnosis, whereas Diamond–Blackfan anemia is a lifelong affliction. Other disorders associated with decreased red cell production such as renal failure, hypothyroidism, and the anemia of chronic disease need to be considered.
Oral corticosteroids should be initiated as soon as the diagnosis of Diamond–Blackfan anemia is made. Two-thirds of patients will respond to prednisone, 2 mg/kg/d, and many of those who respond subsequently tolerate significant tapering of the dose. Patients who are unresponsive to prednisone require chronic transfusion therapy, which inevitably causes transfusion-induced hemosiderosis and the need for chelation with parenteral deferoxamine. Bone marrow transplantation is an alternative therapy that should be considered for transfusion-dependent patients who have HLA-matched siblings. Hematopoietic growth factors have been used in some cases with limited success. Unpredictable, spontaneous remissions occur in up to 20% of patients.
The prognosis for patients responsive to corticosteroids is generally good, particularly if remission is maintained with low doses of alternate-day prednisone. Patients dependent on transfusion are at risk for the complications of hemosiderosis, including death from congestive heart failure, cardiac arrhythmias, or hepatic failure. This remains a significant threat, particularly during adolescence, when compliance with nightly subcutaneous infusions of deferoxamine is often difficult to ensure.
Berndt A: Successful transplantation of CD34+ selected peripheral blood stem cells from an unrelated donor in an adult patient with Diamond-Blackfan anemia and secondary hemochromatosis. Bone Marrow Transplant 2005;35:99. [PMID: 15516941]
Vlachos A: Hematopoietic stem cell transplantation for Diamond–Blackfan anemia: A report from the Diamond–Blackfan Anemia Registry. Bone Marrow Transplant 2001;27:381. [PMID: 11313667]
خالص شكري وتقديري د-عبد الهادي الجريصي </p>