Platelet count
Key points
- Platelets are necessary for normal blood clotting (hemostasis).
- Blood is drawn from a vein, usually on inside of the elbow or the back of the hand.
- The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust.
- When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation.
Alternative names
Thrombocyte count
Definition
This is a test to measure the number of platelets in blood.
Platelets are necessary for normal blood clotting (hemostasis). Most important, they aggregate (clump together) to plug small holes in damaged blood vessels. They also activate factor VIII (a component of the coagulation cascade) and release phospholipids necessary for coagulation.
How the test is performed
Blood is drawn from a vein, usually on 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.
For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test
No special preparation is necessary.
Infants and 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 your child, see the following:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- School age test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
How the test will feel
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.