Serum procollagen type 1 N propeptide: A novel diagnostic test for diabetic foot osteomyelitis – A case–control study

Background: The objective of the study was to determine whether serum levels of procollagen type 1 N propeptide (P1NP), a bone formation turnover marker, differs between diabetic foot ulcer with osteomyelitis (DFO) and diabetic foot ulcers without osteomyelitis serving as controls. It was also aimed to assess the usefulness of P1NP in diagnosing DFO compared to other common inflammatory markers. Materials and Methods: A case–control study was designed comparing the aforementioned groups. Patients were classified as osteomyelitis and controls based on the International Working Group diagnostic criteria. Serum P1NP and three other inflammatory markers, namely, C‑reactive protein (CRP), white blood cells (WBC), and platelets were analyzed on patients with DFO and controls. Results: The mean serum P1NP levels were significantly higher in the DFO group (n: 16), 10.5 ± 5.2 (ng/ml), than the control group (n: 11) 3.1 ± 2.8 (ng/ml), P = 0.001. P1NP showed the highest sensitivity/specificity 86.7%/80% compared to 70.6%/80%, 56.2%/45.4%, and 50%/37% for CRP, WBC and platelets, respectively. Receiver operator characteristic curves showed the best value of area under the curve of 0.9 for P1NP compared to 0.85, 0.54, and 0.46 for CRP, WBC, and platelets. Conclusion: We found marked elevation of serum P1NP in diabetic foot ulcer with bone infection with potential value in using it to diagnose DFO.