SERUM PROCALCITONIN AS AN INDEX OF INHALATION INJURY IN BURNS

The molecular heterogeneity of serum immunoreactive calcitonin (iCT) was analyzed from a prospective study of 41 burn patients. Using different region-specific anticalcitonin antisera, the ratio of mid-region-recognizing to carboxyl terminal-region-recognizing iCT was found to increase acutely in those who subsequently died. The highest ratios occurred in those who died early of respiratory complications. Sephadex chromatography and reversed-phase HPLC demonstrated that the serum iCT circulated predominantly in the large molecular mass prohormone form (16 kDa). In comparison, iCT of normal human lung and of normal thyroid was shown to consist primarily of smaller monomeric mass forms. Furthermore, in 12 normal volunteers who were evaluated with a calcium-pentagastrin infusion, the ratio of iCT levels did not differ from the baseline ratio despite a 50% increase in serum iCT. These results suggest that in burns, the inhalational injury-associated hypercalcitonemia is characterized by a preferential release of procalcitonin; a form of constitutive secretion. The measurement of serum procalcitonin levels would appear to be a useful prognostic indicator of the severity of inhalational injury occurring in burn patients.