Human placental lactogen

Alternative names 

This is a blood test that measures the amount of the hormone human placental lactogen (HPL).

How the test is performed

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to 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 band 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
No special preparation is needed.

For children:
The preparation you can provide for this test depends on your child’s age, previous experiences, and level of trust. For specific information regarding how you can prepare a child 12 to 18 years, see adolescent test or procedure preparation.

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
HPL is a placental hormone that induces insulin resistance and carbohydrate intolerance. HPL also breaks down maternal fats to provide fuel for the fetus.

Normal Values
A rising HPL value during pregnancy is normal.

What abnormal results mean

HPL is a hormone produced by the placenta and this test is used to evaluate how well the placenta is functioning. Abnormal results may indicate abnormal (usually insufficient) placenta function.

HPL values are decreased with:

  • toxemia  
  • aborting molar pregnancy (see hydatidiform mole)  
  • choriocarcinoma  
  • placental insufficiency

HPL values are increased with:

  • multiple pregnancies  
  • placental site trophoblastic tumor  
  • intact molar pregnancy  
  • diabetes  
  • Rh incompatibility

What the risks are

  • excessive bleeding  
  • fainting or feeling lightheaded  
  • hematoma (blood accumulating under the skin)  
  • infection (a slight risk any time the skin is broken)  
  • multiple punctures to locate veins

Special considerations

The clinical value of this test is limited to certain rare conditions and research purposes.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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