gray-top tube

gray-top tube

(grā-top tūb)
A container with potassium oxalate used as an anticoagulant and sodium fluoride as a preservative; used to maintain glucose in whole blood and for some special chemistry tests.
References in periodicals archive ?
Also, with the gray top drawn after the green top, neither potassium oxalate nor sodium fluoride in the gray-top tubes would contaminate sodium or potassium testing.