Estriol - serum
Alternative names:
serum estriol
How the test is performed:
Estriol is a specific type of estrogen hormone. Estriol excretion studies can be done using 24-hour urine tests or blood studies. Serial studies are usually begun at about 28 to 30 weeks of gestation and are repeated weekly. The frequency of the tests may be increased in high-risk pregnancies.
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
How to prepare for the test:
Consult the health care provider about interfering factors such as an urinary tract infection.
Drugs that can increase test measurements include adrenocorticosteroids (corticosteroids), estrogen-containing drugs, phenothiazines, and tetracyclines.
Drugs that can decrease test measurements include clomiphene.
Children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed:
The most common use of estriol measurements is in the evaluation of fetal status during pregnancy. Serial urine and/or blood studies for estriol excretion provide an objective means of assessing placental function and fetal normality in high-risk pregnancies. Excretion of estriol increases around the eighth week of gestation and continues to rise until shortly before delivery. Rising values indicate an adequately functioning "fetoplacental unit". Decreasing values suggest fetoplacental deterioration.
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