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Elevated alpha-fetoprotein refers to a state where alpha-fetoprotein levels are outside of the reference range. There are two categories of AFP tests: tests performed on serum (blood plasma), and tests performed on amniotic fluid. Tests performed on serum are further categorized by the reason for performing the test: maternal serum, adult tumor ...
Since AFP is quickly cleared from the mother's serum via her kidneys, maternal urine AFP correlates with fetal serum levels, although the maternal urine level is much lower than the fetal serum level. AFP levels rise until about week 32. Maternal serum alpha-fetoprotein (MSAFP) screening is performed at 16 to 18 weeks of gestation. [20]
At birth, infants have relatively high levels of AFP, which fall to normal adult levels by the second year of life. The normal level for AFP in children has been reported as lower than 50 nanograms per milliliter (ng/ml) and 10 ng/ml in adults. An AFP level greater than 500 ng/ml is a significant indicator of hepatoblastoma.
AFP concentrations are abundant in the human fetus but decline after birth. [11] In adults a normal amount of AFP is 0-40nng/mL and high levels of this can indicate diseases, cancer, and fetal defects. In pregnant people AFP levels rise at 14 weeks until 32 weeks, and range between 10 and 150 ng/mL in the middle of gestation.
Second-trimester maternal serum screening (AFP screening, triple screen, quad screen, or penta screen) can check levels of alpha fetoprotein, β-hCG, inhibin-A, estriol, and h-hCG (hyperglycosolated hCG) in the woman's serum. The triple test measures serum levels of AFP, estriol, and beta-hCG, with a 70% sensitivity and 5% false-positive rate.
The most common abnormality the test can screen is trisomy 21 (Down syndrome).In addition to Down syndrome, the triple and quadruple screens assess risk for fetal trisomy 18 also known as Edwards syndrome, open neural tube defects, and may also detect an increased risk of Turner syndrome, triploidy, trisomy 16 mosaicism, fetal death, Smith–Lemli–Opitz syndrome, and steroid sulfatase ...
Triploidy may be suggested by dramatically elevated levels of serum alpha-fetoprotein. On obstetric ultrasonography, abnormalities of the skeleton, central nervous system, heart, abdomen, and kidneys are visible in the most severe cases beginning at 12-14 weeks of pregnancy. Placental abnormalities associated with a triploid pregnancy become ...
Spina bifida can usually be detected during the second trimester of pregnancy by fetal ultrasound. [59] Increased levels of maternal serum alpha-fetoprotein (MSAFP) should be followed up by two tests – an ultrasound of the fetal spine and amniocentesis of the mother's amniotic fluid (to test for alpha-fetoprotein and acetylcholinesterase).