Differential diagnosis between infections and neoplastic fever is a common diagnostic problem. The utility of admission serum concentrations of neopterin and interleukin 12 (IL-12) was prospectively evaluated in this respect. The infection group (n=56) had a higher median neopterin value (12.8 nmol/l vs 4.0 nmol/l, P<0.001) and neopterin-to-IL-12 ratio (1.74 vs 0.11, P<0.001) than the non-infection group (n=36); the median IL-12 values were higher in the latter group (10.6 pg/ml vs 71.6 pg/ml, P=0.007). According to the area under the operating characteristics curves (AUC), especially neopterin (0.90), but also the neopterin-to-IL-12 ratio (0.79), was good at identifying bacteremia. However, in differentiating infections in general from neoplastic fever (n=10), the neopterin-to-IL-12 ratio was less powerful (0.64), though still better than neopterin (0.58) and clearly better than IL-12 (0.42). The present results show that the neopterin-to-IL-12 ratio, which reflects simultaneously both the ongoing infection and the tumour load, may have promising clinical implications for differential diagnosis between infections and neoplastic fever.
Copyright 2001 Academic Press.