Which anticoagulant is preferred for accurate phosphate measurement?

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Multiple Choice

Which anticoagulant is preferred for accurate phosphate measurement?

When you measure phosphate in blood samples, you want an anticoagulant that doesn’t interfere with the phosphate chemistry or bind/alter other ions in the sample. Heparin fits that role because it prevents clotting without chelating calcium or magnesium or reacting with phosphate itself. This keeps the inorganic phosphate in its true form so the assay—often a molybdate-based colorimetric method—gives an accurate result. Other common anticoagulants can skew the reading: EDTA chelates divalent cations, which can disturb phosphate equilibria and interfere with the assay. Citrate also chelates calcium and can change the sample’s ionic environment or form complexes that affect measurement. Fluoride isn’t an anticoagulant and is mainly used to inhibit glycolysis in glucose testing; it can alter enzyme activities involved in some phosphate assays.

When you measure phosphate in blood samples, you want an anticoagulant that doesn’t interfere with the phosphate chemistry or bind/alter other ions in the sample. Heparin fits that role because it prevents clotting without chelating calcium or magnesium or reacting with phosphate itself. This keeps the inorganic phosphate in its true form so the assay—often a molybdate-based colorimetric method—gives an accurate result.

Other common anticoagulants can skew the reading: EDTA chelates divalent cations, which can disturb phosphate equilibria and interfere with the assay. Citrate also chelates calcium and can change the sample’s ionic environment or form complexes that affect measurement. Fluoride isn’t an anticoagulant and is mainly used to inhibit glycolysis in glucose testing; it can alter enzyme activities involved in some phosphate assays.

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