Admission neopterin and interleukin 12 concentrations in identifying infections in adult cancer patients

Differential diagnosis between infections and neoplastic fever is a common diagnostic problem. The utility of admission serum concentrations of neopte rin 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<0.0 01) than the non-infection group (n = 36); the median IL-12 values were hig her in the latter group (10.6 pg/ml vs 71.6 pg/ml, P=0.007). According to t he area under the operating characteristics curves (AUC), especially neopte rin (0,90), but also the neopterin-to-ll-lt ratio (0,79), was good at ident ifying bacteremia, However, in differentiating infections in general from n eoplastic 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, whic h reflects simultaneously both the ongoing infection and the tumour load, m ay have promising clinical implications for differential diagnosis between infections and neoplastic fever. (C) 2001 Academic Press.