Fluoride is used in: (A) Blood glucose estimation samples, (B) Urine glucose estimation samples, (C) Both 1 & 2, (D) None of the above
Answer is A. The high energy compound phosphoenol pyruvate is generated from 2-phosphoglycerate by the enzyme enolase. This enzyme requires Mg2+ or Mn2+ and is inhibited by fluoride. For blood  glucose estimation in the laboratory, fluoride is added to the blood to prevent glycolysis by the cells, so that blood glucose is correctly estimated.