title: False positive Kleihauer results: an unusual cause in a postnatal patient in remission from acute myeloid leukaemia.
abstract: A 34-year-old woman, in remission from acute myeloid leukaemia, had a positive postnatal Kleihauer result. Following our standard local protocol for positive Kleihauer tests in Rh-D negative patients, the specimen was referred for confirmatory testing, which proved the result to be false positive. Hereditary persistence of foetal haemoglobin was excluded as a Kleihauer test performed in a pregnancy prior to the development of leukaemia was negative. Further testing confirmed mild elevation of foetal haemoglobin (HbF) and increased F-cells. Elevated-HbF levels have been widely reported in patients with haematological malignancy. In this case, the patient was confirmed to be in a true molecular remission from leukaemia and yet appeared to have a residual clonal population of HbF erythrocytes; the significance of this finding remains unclear. This case also highlights the importance of confirmatory testing of suspected foeto-maternal haemorrhage, as not all positive Kleihauer tests are true positives.
authors.affiliation: Department of Haematology, Queen Elizabeth Hospital, Kings Lynn, Norfolk, United Kingdom. rowan.grant@qehkl.nhs.uk
authors.forename: R
authors.initials: R
authors.lastname: Grant
authors.forename: J
authors.initials: J
authors.lastname: Keidan
mesh_terms: D000328:Adult; D005189:False Positive Reactions; D005260:Female; D005319:Fetal Hemoglobin / Q000032:analysis*; D006443:Hemoglobin A2 / Q000032:analysis*; D006801:Humans; D006918:Hydroxyurea / Q000627:therapeutic use; D015470:Leukemia, Myeloid, Acute / Q000097:blood* / Q000188:drug therapy; D009365:Neoplasm Regression, Spontaneous
chemical_list: D006443:Hemoglobin A2; D005319:Fetal Hemoglobin; D006918:Hydroxyurea