Final answer:
A patient with Goodpasture syndrome and acute tubular necrosis has hyperphosphatemia, which requires controlling phosphorus levels to prevent hypocalcemia.
Step-by-step explanation:
A patient with Goodpasture syndrome who has developed acute tubular necrosis and has a phosphorus level of 6.5 mg/dl is experiencing hyperphosphatemia. This is a condition characterized by abnormally increased levels of phosphates in the blood, often due to decreased renal function.
Control of the phosphorus level is important to avoid complications from hypocalcemia, which is abnormally low blood levels of calcium. When phosphate levels in the blood are high, it can bind with free calcium, thus lowering the amount of available calcium, possibly leading to hypocalcemia.