PhlebotomyQuestion 55 of 100
A lavender-top (purple) tube is required for a complete blood count (CBC). Which additive does it contain?
a.Sodium fluoride
b.Sodium citrate
c.EDTA
d.Sodium heparin
Explanation
The lavender-top tube contains EDTA, an anticoagulant that binds calcium and preserves the shape of blood cells, making it ideal for hematology tests such as the CBC. It must be gently inverted several times after collection to mix the additive. Clots form if it is not mixed, invalidating the sample.
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Related questions on this topic
- According to the standard order of draw, which specimen is collected first when a blood culture is ordered along with other tests?
- In the CLSI order of draw, which tube is collected immediately after blood culture bottles?
- A green-top tube is used for many chemistry (plasma) tests. Which additive does it contain?
- A gray-top tube containing sodium fluoride is most appropriate for which test?
- A plain red-top tube (no additive or with clot activator only) is typically used to collect which specimen type?
- At what angle should the needle be inserted during a routine venipuncture?
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