APT Test, Stool
HbF, Fetal Hemoglobin, Alkali Denaturation Test
EPIC: LAB5010, APT
The APT test is a qualitative procedure used to visually detect Fetal hemoglobin in a neonatal stool or gastric specimen. A specimen that does not show visual evidence of gross blood (pink red) upon receipt by the Laboratory is inappropriate for analysis.
Specimen Collection Criteria
Collect: Random stool specimen or gastric contents in a sterile collection container.
- It is required that the specimen be red (grossly bloody) and not tarry.
- Transport specimen to the Laboratory immediately after collection.
Specimens that are not red/grossly bloody.
Do not store the specimen. Analyze immediately upon receipt in the Laboratory.
Specimen Stability for Testing:
Room Temperature (20–26°C or 68–78.8°F): 1 hour
Refrigerated (2–8°C or 36–46°F): 1 hour
Frozen (-20°C/-4°F or below): Unacceptable
Specimen Storage in Department Prior to Disposal:
Specimens are disposed within 8 hours of testing.
Royal Oak Automated Chemistry Laboratory
Sunday – Saturday, 24 hours a day.
STAT results available within 2 hours of receipt in the Royal Oak Laboratory.
Routine results available within 24 hours.
Manual/Qualitative, Alkali Denaturation.
The test depends on the stability of fetal hemoglobin in the presence of alkali. Following addition of alkali and centrifugation, fetal hemoglobin will remain pink/red, whereas Hb A from maternal blood will be converted to alkaline hematin in 1-2 minutes and the solution will become yellow-brown.
The test is performed to determine whether fresh blood present in neonatal stool or gastric contents is of maternal or neonatal origin, however test sensitivity is poor (i.e., detection of small amounts of blood from a neonate is low). Red cells from a neonate will contain greater than or equal to 70% fetal hemoglobin, whereas maternal red cells normally contain less than 2% fetal hemoglobin.
Automated Chemistry Laboratory – RO
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