This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
If you are in PHC, which anticoagulant is used to sent the blood sample for blood glucose estimation? 
Select and explain. 
A. EDTA, B. Heparin, C. Potassium oxalate, D. Potassium oxalate + sodium fluoride
D: Potassium oxalate + sodium fluoride
Answer: D: Potassium oxalate + sodium fluoride 
Explanation: Sodium fluoride- potassium oxalate mixture is used for glucose determination.
NaF inhibits the glycolytic enzymes responsible for the breakdown of glucose in the blood ( At room temperature, about 10% of the glucose is lost per hour from an untreated sample).
The potassium oxalate is the primary anticoagulant, as NaF has a poor anticoagulant effect.