How to Calculate Beta HCG

Beta human chorionic gonadotropin (HCG) is a hormone produced in the human body. Beta HCG levels are greatly elevated during pregnancy, and this change forms the premise of most pregnancy tests. In most pregnancies, the HCG level will double every 48 to 72 hours for the first few weeks before slowing down. Multiple HCG tests should be performed over several days to verify a positive result. HCG tests are available earlier than ultrasound, however HCG tests are less accurate because some women may not display high levels of HCG. The quantitative HCG test is a blood test that determines how much HCG is in the patient's blood and serum.

Things You'll Need

• Needle
• Gloves
• Antiseptic fluid
• Elastic band
• Bandage
• Plasma separator tube
• Chorionic gonadotropin assay

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Instructions

Collecting the sample

• 1

  Lower-than-normal levels of HCG may indicate an ectopic pregnancy, incomplete miscarriage or fetal death.

  Select a site to draw blood, usually from the inside of the elbow or on the back of the hand. Clean the site with antiseptic fluid.

• 2

  Higher-than-normal levels of HCG may indicate pregnancy, ovarian cancer, testicular cancer or choriocarcinoma of the uterus.

  Wrap an elastic band around the upper arm to apply pressure to the vein. The vein should swell slightly.

• 3

  The blood is gathered into an air-tight tube that separates the plasma from the red blood cells.

  Insert the needle into the vein and collect a sample of blood. Remove the needle and the elastic band.

• 4

  Bandages help prevent infection and stop excessive bleeding.

  Cover the puncture site with a bandage to stop any bleeding.

Test the sample

• 5

  The correct immunoassay should be selected based on what pathology is suspected.

  Follow the instructions of the HCG assay. Different HCG immunoassay products follow different directions, so be sure to consult the manual of the correct assay.

• 6

  Obtaining a blood sample from one patient may be more difficult than from others.

  Compare the results to a reference table to determine if HCG levels are higher or lower than normal. For males, less than 2.0 mIU/mL is normal. For non-pregnant females, less than 3.0 mIU/mL is normal.

• 7

  Diuretics may lower HCG levels and interfere with results.

  Consider medications the patient may be taking when analyzing the test results. Diuretics and promethazine may lower HCG levels. Anticonvulsants, anti-parkinsonian drugs, phenothiazine and promethazine may increase HCG levels. These medications rarely cause false-negatives or false-positives, but it is possible.