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Chest. 2003 Dec;124(6):2119-25.

Study of Clara cell 16, KL-6, and surfactant protein-D in serum as disease markers in pulmonary sarcoidosis.

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Heart Lung Center Utrecht, Department of Pulmonology, St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, the Netherlands.



To determine the discriminative value of serum Clara cell 16 (CC16), KL-6, and surfactant protein (SP)-D as markers of interstitial lung diseases, and their ability to reflect pulmonary disease severity and prognosis in sarcoidosis.


Seventy-nine patients with sarcoidosis and 38 control subjects.


Serum CC16, KL-6, and SP-D concentrations at disease presentation were measured. Pulmonary function tests and chest radiographs were analyzed at presentation and 2-year follow-up.


All markers co-correlated, and a significant difference was found between CC16, KL-6 (Krebs von den Lungen-6), and SP-D levels in patients with sarcoidosis and control subjects (p < 0.0001). Receiver operating characteristic curve analysis revealed largest area under the curve for KL-6. Significantly higher levels of CC16 and KL-6 were found in patients with parenchymal infiltration (stage II, III) compared to patients without parenchymal infiltration (stage I). In concordance, CC16 and KL-6 levels inversely correlated with diffusion capacity and total lung capacity, and KL-6 also with inspiratory vital capacity. Moreover, higher KL-6 levels were weakly but significantly associated with persistence or progression of parenchymal infiltrates at 2-year follow-up.


In this study, KL-6 appears to be the best discriminative marker in differentiating patients with sarcoidosis from healthy control subjects; however, as it is not a specific marker for this condition, this quality is unlikely to be useful as a diagnostic tool. Both CC16 and KL-6 may be of value in reflecting disease severity, and KL-6 tends to associate with pulmonary disease outcome.

[Indexed for MEDLINE]

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