Which preanalytic factor can cause an erroneous elevation of serum inorganic phosphate results?

Which preanalytic factor can cause an erroneous elevation of serum inorganic phosphate results?

• A. Patient not fasting when blood drawn
• B. Specimen was hemolyzed
• C. Effect of diurnal variation
• D. Patient receiving intravenous glucose therapy

Answer: (B)

Hemolysis as a preanalytic artifact can cause an artificial rise in serum inorganic phosphate. Red blood cells contain phosphate inside their cells, so when a blood sample is hemolyzed, the phosphate leaks into the serum. This release raises the measured inorganic phosphate level in the test result, even if the patient’s true serum phosphate isn’t elevated. That’s why a hemolyzed specimen often leads to falsely high phosphate results and why samples showing hemolysis are typically re-collected if possible. Not fasting can influence some analytes, but it doesn’t reliably produce a spurious elevation in phosphate. Diurnal variation is a normal physiological fluctuation and isn’t an error introduced by the preanalytic process. Intravenous glucose therapy tends to drive phosphate into cells (via insulin), which can lower serum phosphate rather than raise it, so it wouldn’t explain an artificial elevation.

Hemolysis as a preanalytic artifact can cause an artificial rise in serum inorganic phosphate. Red blood cells contain phosphate inside their cells, so when a blood sample is hemolyzed, the phosphate leaks into the serum. This release raises the measured inorganic phosphate level in the test result, even if the patient’s true serum phosphate isn’t elevated. That’s why a hemolyzed specimen often leads to falsely high phosphate results and why samples showing hemolysis are typically re-collected if possible.

Not fasting can influence some analytes, but it doesn’t reliably produce a spurious elevation in phosphate. Diurnal variation is a normal physiological fluctuation and isn’t an error introduced by the preanalytic process. Intravenous glucose therapy tends to drive phosphate into cells (via insulin), which can lower serum phosphate rather than raise it, so it wouldn’t explain an artificial elevation.