Since her RBC count and platelets are low with the bone marrow suggestive of hypocellular marrow, it seems the cause is bone marrow supression or aplastic anemia. The cause of aplastic anemia are varied and could be due to drugs such as antibiotics, chemotherapy agents and even infections such as parvovirus infection, Hepatitis B and even HIV infection. In some children it could be due to congenital cause such as Fanconi's anemia which can be diagnosed by doing chromoomal analysis for frequent breaks. Regarding normal values for CBC, it depends on the normal range for that lab. You can also read the article on "Routine blood test " on www.pediatriconcall.com or from the link given below:

http://www.pediatriconcall.com/forpatients/Procedures/routine_blood_testpat.asp

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