What is the normal serum phosphorus value?

What is the normal serum phosphorus value?

• A. 1.0-2.0 mg/dL
• B. 3.0-4.0 mg/dL
• C. 2.4-4.4 mg/dL
• D. 4.5-5.5 mg/dL

Answer: (C)

Normal serum phosphorus in adults is about 2.5-4.5 mg/dL. The range 2.4-4.4 mg/dL matches the commonly cited reference interval used in NCLEX and clinical labs, so it’s the best choice. Values below this (e.g., 1.0-2.0 mg/dL) indicate hypophosphatemia, which can occur with malnutrition, alcoholism, or refeeding after starvation. Values above this (e.g., 4.5-5.5 mg/dL) indicate hyperphosphatemia, seen with renal failure or hypoparathyroidism. The 3.0-4.0 mg/dL range is within normal limits but doesn’t reflect the full reference span typically used, so it’s not the best match.

Normal serum phosphorus in adults is about 2.5-4.5 mg/dL. The range 2.4-4.4 mg/dL matches the commonly cited reference interval used in NCLEX and clinical labs, so it’s the best choice. Values below this (e.g., 1.0-2.0 mg/dL) indicate hypophosphatemia, which can occur with malnutrition, alcoholism, or refeeding after starvation. Values above this (e.g., 4.5-5.5 mg/dL) indicate hyperphosphatemia, seen with renal failure or hypoparathyroidism. The 3.0-4.0 mg/dL range is within normal limits but doesn’t reflect the full reference span typically used, so it’s not the best match.