Surfactant protein-D is more useful than Krebs von den Lungen 6 as a marker for the early diagnosis of interstitial pneumonitis during pegylated interferon treatment for chronic hepatitis C.

BACKGROUND/AIMS: To examine the usefulness of serum Krebs von den Lungen 6 (KL-6) and surfactant protein-D (SP-D) as markers of interstitial pneumonitis. Many antiviral therapies have become available for chronic hepatitis C, including pegylated interferon (PEGIFN) plus ribavirin. Since interstitial pneumonitis is a serious adverse drug reaction during interferon therapy, interferon treatment requires caution in respiratory disease patients. Hence, the predictors of interstitial pneumonitis have not been elucidated.

METHODOLOGY: Fifty-two chronic hepatitis C patients who received PEG-IFN plus ribavirin were studied; 14 patients received PEGIFN-α 2a, and 38 received PEG-IFN-α 2b. Serum KL-6 and SP-D levels were measured during treatment. Time changes in serum KL-6 and SP-D levels, as well as the presence of interstitial pneumonitis, were investigated.

RESULTS: No cases of pneumonitis in which both markers were below the standard values were seen. Interstitial pneumonitis developed in 1 of the 5 patients in whom both markers were above standard values. Patients whose KL-6 levels alone exceeded the standard value had bacterial pneumonia and emphysema, not interstitial pneumonitis. Though no correlation between SP-D and KL-6 levels was observed, KL-6 levels tended to increase after interstitial pneumonitis was detected on imaging, but SP-D levels increased before imaging detection.

CONCLUSIONS: It is important to monitor changes in levels of serum markers and other factors to avoid interstitial pneumonitis during PEG-IFN therapy. SP-D in particular may be important for early detection of interstitial pneumonitis.