Diagnosis

    Newborn screening

  • High performance liquid chromatography (HPLC) testing to determine the presence of abnormal hemoglobins (Hgb) in whole blood is the method usually used in newborn screening
  • HPLC is effective in detecting hemoglobinopathies characterized by synthesis of an abnormal hemoglobin molecule immediately after birth
  • Normal infants will have mostly fetal hemoglobin (Hgb F) and some adult hemoglobin (Hgb A)
  • A baby testing positive for a hemoglobinopathy will have Hgb F, with Hgb S, Hgb C or another form of abnormal hemoglobin
  • All abnormal newborn screening test results indicating more serious hemoglobinopathies (those requiring prophylactic antibiotics) require appropriate confirmatory blood tests
  • Additional tests including testing of parents and siblings may be necessary for actual diagnosis
  • Referral to a pediatric hematologist for evaluation and diagnostic testing is recommended in these cases, preferably within the first month of life
  • If newborn screening results indicate less serious hemoglobin disorders or traits, referral to a pediatric hematologist for parental education and counseling is recommended
  • Even small transfusions may cause false negative screening test results and any results indicating that the baby was transfused require repeat testing 90 days after the last transfusion
  • Other methods

    Several testing methods are available for diagnosis of sickle hemoglobinopathies. These tests are reliable and accurate methods for defining an infant's hemoglobin phenotype. These include

  • Hemoglobin electrophoresis including both cellulose acetate and citrate agars (one is not sufficient)
  • Isoelectric focusing
  • High performance liquid chromatography
  • The Sickledex test is a simple solubility test that becomes positive if there is > 10% Hb S It does not distinguish between sickle cell trait and sickle cell disorders, and gives no information about the other abnormal hemoglobins such as Hgb C, D or E. Therefore; it should not be used to diagnose sickle cell disease

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