What is the normal serum phosphate range?

What is the normal serum phosphate range?

• A. 1.5–3.5 mg/dL
• B. 2.5–4.5 mg/dL
• C. 3.5–5.5 mg/dL
• D. 4.5–6.5 mg/dL

Answer: (B)

Normal serum phosphate in adults is typically 2.5 to 4.5 mg/dL. This range reflects how phosphate balance is maintained by the kidneys, bones, and gut, with regulatory input from parathyroid hormone and vitamin D. In practice, most adults fall within this window, and values outside it signal disturbances: higher levels point to issues like kidney dysfunction or hypoparathyroidism, while lower levels can occur with malnutrition, refeeding after starvation, or excessive phosphate loss. Lab reference ranges can vary slightly by method, but 2.5–4.5 mg/dL is the common standard, so it best matches the usual adult reference.

Normal serum phosphate in adults is typically 2.5 to 4.5 mg/dL. This range reflects how phosphate balance is maintained by the kidneys, bones, and gut, with regulatory input from parathyroid hormone and vitamin D. In practice, most adults fall within this window, and values outside it signal disturbances: higher levels point to issues like kidney dysfunction or hypoparathyroidism, while lower levels can occur with malnutrition, refeeding after starvation, or excessive phosphate loss. Lab reference ranges can vary slightly by method, but 2.5–4.5 mg/dL is the common standard, so it best matches the usual adult reference.