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Ellis Neufeld, MD, PhD, associate chief, Division of Hematology/Oncology |
Anemia is one of the most common pediatric disorders. Here, Children's Hospital Boston
hematologist Ellis Neufeld, MD, PhD, talks about screening for anemia and clues that pediatricians can look for when trying to determine the type and cause.
What are the most common types of anemia?
In otherwise healthy children, iron deficiency is still by far the most common. Mild anemia can accompany any systemic illness, including trivial intercurrent viruses. Patients with any
inflammatory state can have anemia of inflammation, previously known as "anemia of chronic disease." Anemias are most easily classified by cell size (low, normal or large) as microcytic,
normocytic and macrocytic. Iron deficiency, lead poisoning and thalassemia states are the most common microcytic anemias. Normocytic anemia can be a sign of systemic illness (liver, thyroid or kidney, for example), bleeding, hemolysis or inflammation. Macrocytic anemia is often caused by a deficiency of folic acid or vitamin B12; medications, especially chemotherapy agents and some seizure drugs; ethanol; or congenital or acquired marrow failure syndromes.
Who is at risk?
This can include children with dietary predisposition to iron
deficiency (vegetarians, those with excessive milk intake), as well as children with systemic illness, seizure disorders and suggestive family histories.
How and when should children be screened for anemia?
Anemia can usually be identified through routine screening. The American Academy of Pediatrics recommends screening children by their 12 month visit, with additional screenings between the ages of 1 and 5 for patients who are at risk. This screening
paradigm is meant mainly to catch iron deficiency and lead
ingestion, so that treatment can be initiated, but many other types of anemia are found with screening studies.
What tests do you recommend?
The most common approach is a complete blood count (CBC) to measure red blood cell count, hemoglobin level/hematocrit and mean corpuscular volume (MCV). Reticulocyte count is helpful to distinguish production problems (low retics) from red cell loss (bleeding or hemolysis, high retics). The MCV allows classification of anemia (hemoglobin below lower normal for age) as described above. It should be noted that MCV is age-dependent. In young children, low-normal is approximately 70 fl plus the age in years, so that MCV 73 fl is normal in a 2-year-old, but abnormal in an
8-year-old.
A CHr (reticulocyte hemoglobin content) test may also be used to test for iron deficiency. Some studies suggest that this may be better than a standard hemoglobin test. Because
reticulocytes circulate for only one to two days, compared with 100 days for mature red cells, their hemoglobin content is a
timelier indicator of iron status. Thus, a trial of iron can improve the CHR in iron deficiency in five to seven days, whereas the hemoglobin level will take a month or more to improve. A
peripheral blood smear is very helpful in distinguishing types
of anemia.
How do you distinguish between types of anemia?
Additional testing is often needed once you've classified the anemia type by cell size. Thalassemia trait is a very common cause of
microcytosis and must be
distinguished from iron deficiency. A simple and inexpensive
discriminating test is to challenge the patient with iron therapy. If their red blood cells don't respond, then thalassemia should be considered. Hemoglobin
electrophoresis is used to test for beta thalassemia trait. Newborn screening results often have evidence of Hb Barts (FAB
pattern) in alpha thalassemia trait. In normocytic anemia, because systemic illness is a common cause, additional testing may include a TSH test for thyroid function, ALT for liver function,
createnine test to check the kidneys and a CRP test to look for signs of inflammation. An increased count may indicate hemolytic anemia. If the CBC suggests a macrocytic anemia, additional screening may include tests measuring levels of B12 and folic acid. Macrocytic anemia in the absence of vitamin deficiency, drugs or ethanol should always prompt expert consultation.
What treatments do you recommend?
Treatment depends on the type of anemia and the cause.
Iron deficiency anemia is treated by iron supplementation,
while other nutritional deficiencies are treated with the
appropriate vitamin. Hemolytic anemias should be evaluated by a hematologist. Children with thalassemia trait are carriers for a more severe genetic blood disorder called thalassemia major but are not ill themselves. They are usually healthy and normal and don't require treatment.
When should a child be referred to a hematologist?
A referral may be necessary if anemia is suspected and the child has not responded to treatment. A hematologist may be able to definitively diagnose the specific cause of the anemia through further testing.
What are the new findings on iron deficiency?
Children's researchers, including Nancy Andrews, MD, PhD, in the Division of Hematology and Mark Fleming, MD, acting chief of Pathology, have led many recent studies to understand the genetics and physiology of iron metabolism in the body. The
regulation of iron is complex, and, recently, rare familial disorders of iron overload like hemochromatosis and iron deficiency have been the subjects of active research efforts.
More information on anemia and RBC disorders: childrenshospital.org/rbcdisorders.
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