[The usefulness of serum KL-6 levels for the diagnosis of disease activity in idiopathic interstitial pneumonia].

Serum KL-6 levels were measured in 29 patients with idiopathic interstitial pneumonia (IIP) as a means of evaluating disease activity. Levels of serum KL-6 were significantly higher in patients with active IIP (n = 11) than in those with inactive IIP (n = 18). The levels of serum KL-6 were 2,546 +/- 1,703 U/ml in patients with active IIP and 795 +/- 385 U/ml in patients with inactive IIP, respectively. The levels of serum LDH, CEA, P-III-P, and 7 S collagen in patients with active IIP did not differ significantly from those in patients with inactive IIP. For the diagnosis of active IIP, the sensitivity of serum KL-6 (cut off value of 1,500 U/ml) was 81.8% and the specificity, 94.4%. These results were almost identical to findings obtained with chest Ga-67 scintigraphy. Furthermore, they suggested that serum KL-6 levels may be a useful marker for the diagnosis of disease activity in IIP, as well as a useful indicator for the administration of steroid therapy to patients with IIP.