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Disease Markers
Volume 32, Issue 5, Pages 281-287

Serum Surfactant Protein D: Biomarker of Chronic Obstructive Pulmonary Disease

Chun-Rong Ju, Wei Liu, and Rong-Chang Chen

State Key Lab of the Respiratory Disease, Guangzhou Institute of Respiratory Disease, First Affiliated Hospital of Guangzhou Medical College, Guangdong, China

Received 7 March 2012; Accepted 7 March 2012

Copyright © 2012 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background: Surfactant protein D (SP-D) is a lung-specific protein proposed to predict clinical outcomes in patients with chronic obstructive pulmonary disease (COPD). However, the changes in serum SP-D during acute exacerbation (AECOPD) episodes and the relationship of serum SP-D with the overall severity of the disease in stable COPD (SCOPD) remain unclear.

Methods: Serum SP-D levels were analyzed in three groups, including AECOPD (n=40), SCOPD (n=71), and controls (n=60). In AECOPD group, serum SP-D levels were determined at 1, 5, 14, and 30 days post-exacerbation. In SCOPD group, BODE (body mass index, airflow obstruction, dyspnea, exercise capacity) index was evaluated for severity assessment.

Results: Serum SP-D levels were sequentially elevated from the controls to the SCOPD, and then to the AECOPD (p < 0.001). During an AECOPD episode, the raised serum SP-D levels subsided at day 5 (p > 0.05), fell markedly at day 14 (p < 0.001), and continued to decline at day 30 (p < 0.001). Among patients with SCOPD, serum SP-D levels correlated positively with the BODE index (p < 0.01).

Conclusions: The longitudinal changes in serum SP-D levels during an AECOPD episode suggest that SP-D may be a potential systemic biomarker for COPD exacerbation. The correlation of serum SP-D levels with the BODE index suggests that circulating SP-Ds can reflect the overall severity of SCOPD.