Exceeding 7 mmol/hour of phosphate infusion is associated with which risks?

• A. Thrombophlebitis and metastatic calcium-phosphate deposition
• B. Hypophosphatemia and liver failure
• C. Hyperkalemia and hyperglycemia
• D. Hyponatremia and dehydration

Answer: (A)

Infusing phosphate too quickly stresses both the vein and the balance of minerals in the body. Pushing phosphate at rates above 7 mmol/hour increases irritation of the venous lining, raising the risk of thrombophlebitis at the infusion site. More importantly, a high phosphate load can combine with calcium to form calcium-phosphate precipitates that deposit in soft tissues—metastatic calcium-phosphate deposition—potentially affecting organs such as the lungs and kidneys. That combination of local vein inflammation and systemic soft-tissue calcification is why exceeding this rate is associated with these specific risks. The other listed problems aren’t typical direct outcomes of a rapid phosphate infusion.