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Test Code AFPA Alpha-Fetoprotein, Amniotic Fluid

Reporting Name

Alpha Fetoprotein, AF

Useful For

Screening for open neural tube defects or other fetal abnormalities

 

Follow-up testing for patients with elevated serum alpha-fetoprotein results or in conjunction with cytogenetic testing

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
ACHE_ Acetylcholinesterase, AF Yes No

Testing Algorithm

If alpha-fetoprotein is positive, then acetylcholinesterase will be performed at an additional charge.

Method Name

AFPA: Immunoenzymatic Assay

ACHE_: Polyacrylamide Electrophoresis

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Amniotic Fld


Necessary Information


The following information is required:

1. Estimated due date by ultrasound

2. Collection date

3. Gestational age must be between 13 and 24 weeks; 16 to 18 weeks preferred.

 

If not ordering electronically, provide information on Second Trimester Maternal Screening Alpha-Fetoprotein / Quad Screen Patient Information (T595) and send with specimen.



Specimen Required


Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Container/Tube: Plain, plastic, screw-top tube

Specimen Volume: 0.75 mL

Collection Instructions: Do not centrifuge.


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Amniotic Fld Refrigerated (preferred) 7 days
  Ambient  7 days

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

< 2.0 multiples of median (MoM)

Day(s) Performed

Monday through Friday

CPT Code Information

82106

82013 (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
AFPA Alpha Fetoprotein, AF 58735-2

 

Result ID Test Result Name Result LOINC Value
6739 Collection Date 58734-5
DAT15 EDD by US Scan 11781-2
6740 Last Menstrual Period (LMP) 8665-2
24233 EDD by LMP 11779-6
24239 GA at Collection by Scan 11888-5
24240 GA at Collection by Dates 11885-1
24234 GA Used 21299-3
9950 Alpha Fetoprotein, AF 1832-5
24241 Results 29595-6
24235 Interpretation 59462-2
24236 Additional Comments 48767-8
24237 Follow up 80615-8
24238 General Test Info 48767-8

Clinical Information

Alpha-fetoprotein (AFP) is a single polypeptide chain glycoprotein with a molecular weight of approximately 70,000 Da. Synthesis of AFP occurs primarily in the liver and yolk sac of the fetus. It is secreted in fetal serum, reaching a peak at approximately 13 weeks gestation, after which it rapidly declines until about 22 weeks gestation and then gradually declines until term. Transfer of AFP into maternal circulation is accomplished primarily through diffusion across the placenta. Maternal serum AFP levels rise from the normal non-pregnancy level of 0.20 ng/mL to about 250 ng/mL at 32 weeks gestation.

 

If the fetus has an open neural tube defect, AFP is thought to leak directly into the amniotic fluid, causing unexpectedly high concentrations of AFP. Other fetal abnormalities such as omphalocele, gastroschisis, congenital kidney disease, and esophageal atresia; and other fetal distress situations such as threatened abortion, prematurity, and fetal demise, may also show AFP elevations. Decreased amniotic fluid AFP values may be seen when gestational age has been overestimated.

Specimen Retention Time

2 weeks

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

Report Available

2 to 19 days