What is the role of hypocalcemia in hyperphosphatemia?

Updated: Aug 08, 2019
  • Author: Manish Suneja, MD, FASN, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Hyperphosphatemia may be seen in critical illness and in patients who have ingested phosphate-containing enemas. Phosphate binds calcium avidly, causing acute hypocalcemia. Acute hypocalcemia secondary to hyperphosphatemia may also result from renal failure or excess tissue breakdown because of rhabdomyolysis or tumor lysis.

In acute hyperphosphatemia, calcium is deposited mostly in the bone but also in the extraskeletal tissue. In contrast, in chronic hyperphosphatemia, which is nearly always from chronic renal failure, calcium efflux from the bone is inhibited and the calcium absorption is low, because of reduced renal synthesis of 1,25-dihydroxyvitamin D. However, other consequences of renal failure, including a primary impairment in calcitriol synthesis, also contribute to hypocalcemia.


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