Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1146 page)

   Anabolic steroids, corticosteroids, and androgens increase prealbumin levels.

   Estrogens and oral contraceptives decrease prealbumin levels.

   Zinc deficiency, acute alcohol intoxication, leakage of protein from damaged hepatic cells may cause a rise in the prealbumin levels.

   PRENATAL TESTING: SAMPLE COLLECTION PROCEDURES

AMNIOCENTESIS
*

   Definition

   Invasive procedure to obtain amniotic fluid that contains cells sloughed from the fetus. Some biochemical tests can be performed directly on the fluid; most tests first require cell culture. It is generally not performed until 15 weeks of gestation; recent estimates of procedural risk of fetal loss are as low as 0.06%. Cell culture for chromosome analysis takes 5–7 days; slightly longer culture times are required to obtain material for biochemical or molecular genetic tests.

   Use

   Provides fetal material for chromosome (cytogenetic) testing, biochemical testing (metabolic disorders/inborn errors of metabolism), and molecular DNA–based testing for inherited disease (e.g., CF, fragile X).

   Limitations

   Not performed until second trimester, which delays decisions regarding pregnancy termination.

CHORIONIC VILLUS SAMPLING
*

   Definition

   Invasive procedure to obtain chorionic villus tissue generally performed between 10 and 12 weeks of gestation. Procedural risk of fetal loss (higher than for amniocentesis): approximately 1%.

   Use