Septic focus localized by determination of arterio-venous difference in neopterin blood levels

We describe a case of a 38-year-old female accident victim who was admitted to the trauma hospital with an ISS of 66. Successful emergency treatment (including amputation of the left leg) and 4 weeks of intensive care led to an overall improvement so that the patient was extubated on day 29. Throughout this period neopterin was measured routinely 3 times a week and correlated well with the clinical course. At the end of the fifth week massive lung impairment and all clinical signs of sepsis appeared. Neopterin values increased dramatically up to 200 nmol/L. However, no abnormal findings were revealed by X-ray, contrast fluoroscopy, or sonographic imaging. To examine the amputation site more closely, simultaneous determination of neopterin in samples from the vena and arteria femoralis was performed. We found a 50% higher level in the venous blood (300 vs. 200 nmol/L). This was regarded as evidence for a hidden focus. Immediate surgical intervention revealed an abscess, which proved to be Pseudomonas aeruginosa positive. After adequate treatment the patient recovered quickly. In this case neopterin was not only helpful in monitoring the septic episodes of the patient, but proved essential for the detection of a septic focus and the risk of explorative relaparotomy could be omitted.