Pronounced elevation in circulating calcitonin in critical care patients is related to the severity of illness and survival

Abstract

Objective

To study circulating levels of calcitonin in critically ill patients in relation to the severity of illness and survival.

Design

Cross-sectional and prospective.

Setting

The ICU in Gävle hospital, a secondary non-teaching hospital.

Patients

37 consecutive ICU patients.

Measurements and results

Serum calcium and immunoreactive calcitonin (iCT) were measured and the Apache II and the Multiple Organ Failure (MOF) scores were recorded during the first 24 h in the ICU. Patients were followed for hospital survival. Profound increase in circulating iCT was seen (mean 591, median 184, range 8–3445 pg/ml) in the studied sample and only 11% of the patients showed normal levels (<40 pg/ml). iCT was higher in septic than non-septic patients (p<0.004) and was correlated to two indices of severity of illness (r=0.50,p<0.006 versus the Apache II score andp=0.55,p<0.003 versus the MOF score). Furthermore, iCT was correlated to the length of stay in the intensive care unit (r=0.56,p<0.001) and was elevated in the patients who did not survive when compared to survivors (p<0.03). iCT was not significantly related to the degree of serum calcium (mean 2.22±0.15 SD mmol/l). Gel chromatography in a fast protein liquid chromatography (FPLC) system of serum from 4 patients with elevated iCT disclosed that a majority of the measured CT was not due to monomeric CT, but high molecular CT.

Conclusions

Pronounced elevations in circulating iCT were seen during the first 24 h critically ill patients. As the major part of the iCT consisted of high molecular weight CT this would not induce hypocalcemia. Rather, the elevated iCT would be regarded as a part of the metabolic responses to illness.