Diagnostic Use
Serum alpha-fetoprotein is used for the detection and monitoring of hepatocellular carcinoma and some germ cell tumours . (For detecting neural tube defects or Down syndrome, see Maternal Serum Screen )
About 85% of hepatocellular carcinomas are associated with very high levels of serum alpha-fetoprotein (> 100 ug/L), but a normal level does not exclude the diagnosis.
Moderate increases (up to 100 ug/L ) are seen in association with liver cell regeneration e.g. in cirrhosis, chronic active hepatitis.
Increased levels also occur with germ cell tumours of the ovary or testis, or teratomas. These tumours also frequently produce hCG.
A rare cause for raised AFP is Familial Persistence of AFP . This is an asymptomatic condition with no adverse clinical consequences. The raised AFP level is found in other family members.
The half-life of AFP in vivo is about 5 days in adults . In neonates, AFP declines with a half-life of 6 days until 28 days of age; after this the rate of decline is slower – see table above.
References :
1. Blohm ME, Vesterling-Horner D, Calaminus G, Gobel U. Alpha 1-fetoprotein (AFP) reference values in infants up to 2 years of age. Pediatric hematology and oncology 1998;15(2):135-42.
2. Soldin et al. Pediatric Reference Intervals. 6th ed. AACC Press, 2007.
3. CSF reference interval: Mayo Medical Laboratories 2003 Test Catalog.
Reference Intervals
Units: ug/L
|
Age
|
Term Baby (37 week +)
|
Prem Baby (<37 week)
|
|
0 days
|
9,100-190,000
|
31,000-80,0000
|
|
1 day
|
8,000-166,000
|
280,000-710,000
|
|
2 days
|
7,000-145,000
|
25,000-630,000
|
|
3 days
|
6,000-126,000
|
22,000-560,000
|
|
4 days
|
5,300-110,000
|
19,500-500,000
|
|
5 days
|
4,600-96,500
|
17,400-445,000
|
|
6 days
|
4,000-84,500
|
15,300-393,000
|
|
7 days
|
3,500-73,500
|
12,600-350,000
|
|
8-14 days
|
1,500-59,000
|
6,000-312,000
|
|
15-21 days
|
575-23,000
|
2,700-151,000
|
|
22-28 days
|
300-6,300
|
1,200-120,000
|
|
29-45 days
|
30-5,700
|
400-80,000
|
|
46-60 days
|
16-2,000
|
90-39,000
|
|
61-90 days
|
6-1,000
|
20-22,000
|
|
91-120 days
|
3-420
|
10-18,500
|
|
121-150 days
|
2-220
|
4-8,300
|
|
151-180 days
|
1-130
|
3-4,350
|
|
181-270 days
|
0-87
|
3-2,600
|
|
271-365 days
|
0-87
|
3-830
|
|
1 to 2 years
|
0-87
|
0-370
|
|
2y – Adult (non-pregnant):
|
< 10
|
|
Pregnancy
|
|
14 weeks (median)
|
23
|
|
22 weeks (median)
|
60
|
|
30 weeks (median)
|
180
|
CSF : < 1.5 ug/L
Note : The median values for pregnancy are only approximate and should not be used for screening for neural tube defects or other foetal abnormalities.
See Maternal serum screen.
Test Method
Principle : Sandwich type immunoassay with chemiluminescence detection
Reagents : Roche AFP kit
Analyser : Cobas e801
Uncertainty of Measurement
Uncertainty of Measurement: 6%