Scire et al used the serum procalcitonin concentration in the evaluation of a patient with an autoimmune disease who is febrile. This can reduce the unnecessary use of antibiotics. The authors are from the University of Pavia.

Patient selection: autoimmune disease with fever (> 38°C)


A serum procalcitonin > 0.5 ng/mL was associated with systemic infection.

A serum procalcitonin <= 0.5 ng/mL is not associated with systemic infection.


This is helpful in distinguishing a disease flare from systemic infection.


Exception: A patient with adult-onset Still's disease (AOSD) can have an elevated procalcitonin concentration without systemic infection. The elevation in serum procalcitonin may be marked and may be linked to levels of TNF-alpha.


A patient with an infection who is successfully treated will show a decline in the serum procalcitonin concentration.



The sensitivity was 75% and specificity 75% for all patients. The specificity increased to 89% if patients with AOSD are excluded.

The area under the ROC curve is 0.80 for all patients and 0.90 if AOSD is excluded.

CRP and ESR were more sensitive (95%, 100%) for infection but were nonspecific.

To read more or access our algorithms and calculators, please log in or register.