If your patient's phosphorus-rich diet hasn't raised serum phosphorus levels as you had hoped, it's time to ask these questions:

• Is a GI problem making phosphorus digestion difficult?
• Is your patient using a phosphate-binding antacid?
• Is your patient ingesting alcohol regularly or excessively?
• Is your patient using a thiazide diuretic?
• Is your patient's diabetes being adequately managed?