A salt of pyrophosphoric acid; accumulates in cases of hypophosphatasia; sometimes referred to as inorganic p. (PPi). SYN: diphosphate.
- 99mTc p. a radionuclide tracer used for imaging ischemic myocardium in nuclear medicine. See technetium-99m.
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py·ro·phos·phate -'fäs-.fāt n a salt or ester of pyrophosphoric acid
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py·ro·phos·phate (pi″ro-fosґfāt) any salt, anion, or ester of pyrophosphoric acid. Formed during many metabolic reactions, it is an important intermediate because its large free energy of hydrolysis makes the reactions essentially irreversible. The symbol PPi denotes the uncombined form.Medical dictionary. 2011.