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Test Code APT APT Test

Clinical System Name

APT Test


Alkali Denaturation
Fetal Hemoglobin

APT Test Hgb F Qualitative

Downey Test


The APT test uses alkali denaturation of hemoglobin to determine if the blood present in a stool or Emesis sample from a newborn is maternal in origin or if it is due to GI hemorrhage in the patient. 

Sample Requirements

Specimen: Stool,Gastric Aspirate, Emesis, Mucus

Container(s): Sterile Screw-Capped Container  *No absorbing materials (diapers, blankets, etc)

Preferred Vol: 1.0 mL

Minimum Vol: 1.0 mL


Note: Specimens must be grossly bloody. Stools that are tarry and black are not acceptable.

Urine is not acceptable.


Testing should ideally be performed within 30 minutes after it is collected.


Processing Instructions

Reject due to: Reject specimens that are not grossly bloody or stools that are tarry and black. No urines.

Spin: N

Aliquot: N


Storage location: Core 5 Chemistry Refrigerator


Off-site collection: Reject specimens that are not grossly bloody or stools that are tarry and black.

Urine is not acceptable. Test is ideally performed within 30 minutes of collection. Transport refrigerated.



Specimen Type Temperature Time
Stool, Gastric aspirate, Emesis, Mucus RT

48 H


 72 H

  -20oC or -70oC



* Stabilities taken from


STAT Performed TAT
Y 24/7 3 H


Performing Laboratory

Seattle Children's Laboratory    


Department:  Core Chemistry

Phone Number206-987-2561


Lab Client Services206-987-2617


Reference Range



Method: Alkali Denaturation

Analytical Volume: 0.5 mL

CPT Codes