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Test ID: Hemoglobin F (Apt-Downey test)
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Hemoglobin F (Apt-Downey test)
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Hemoglobin F (Apt-Downey test)
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Useful For
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The qualitative determinination for the presence or absence of fetal blood (hemoglobin F) in a neonate's stool or vomitus.
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Method name and description
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A qualitatitve colourimetric test. Hemoglobin F is less susceptible to alkaline denaturation compared to adult hemoglobin.
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Clinical information
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Neonates can exhibit signs suggestive of bleeding. The origin of this blood, however, may not be immediately obvious and it can be helpful to differentiate whether the blood is of maternal or neonatal origin.
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Aliases
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Apt test
Apt-Downey test
Fetal Hemoglobin
Alkaline denaturation test
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Specimen type / Specimen volume / Specimen container
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Fresh neonatal vomitus or stool collected into a plain, clean container
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Collection instructions / Special Precautions / Timing of collection
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A freshly collected sample must be sent immediately to the laboratory.
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Storage and transport instructions
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Samples may be refrigerated at 2-8°C but should otherwise be sent to the lab immediately after collection.
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Specimen Rejection Criteria
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Insufficient sample volume received
Sample more than 24h old
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Biological reference intervals and clinical decision values
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Negative: no hemoglobin F detected.
Positive: hemoglobin F detected.
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Factors affecting test performance and result interpretation
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Samples collected more than 24h prior to receipt in the lab may give false negative results.
Samples collected from non-neonates
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Turnaround time / Days and times test performed / Specimen retention time
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Turnaround time: 2 working days
The test is performed upon receipt of samples
Specimen retention time: 48h
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