Lab Test

APT Test, Stool

HbF, Fetal Hemoglobin, Alkali Denaturation Test , EPIC: LAB5010, SOFT: APT


The APT test is a qualitative procedure used to visually detect the pink color of Fetal hemoglobin present in a 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.

Rejection Criteria

  • Specimens that are not red/grossly bloody.


Specimens should not be stored. This test should be run immediately.


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.

Reference Range


Test Methodology

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.

Clinical Utility

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.

CPT Code


Test Codes


Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.