Table 1. The correlation analysis of serum and pleural YKL-40 levels (ng/mL) according to blood and pleural parameters.

Characteristics	Serum YKL-40, ng/mL			Pleural YKL-40, ng/mL
	r value	P value		r value	P value
Age, year	0.477	<0.001*		–0.112	0.325
Blood
Leucocyte, ×103/mL	0.244	0.029		0.171	0.130
Neutrophils, %	0.205	0.068		0.048	0.673
Lymphocytes, %	–0.023	0.843		0.254	0.023*
Glucose, mg/dL	0.138	0.233		0.022	0.848
Protein, g/dL	–0.226	0.044*		0.144	0.202
Albumin, g/dL	–0.555	<0.001*		–0.013	0.911
LDH, U/L	0.182	0.105		0.540	0.634
Triglyceride, mg/dL	–0.026	0.820		0.213	0.057
Cholesterol, mg/dL	–0.057	0.616		0.189	0.093
Creatinine, mg/dL	0.199	0.077		–0.021	0.853
CRP, mg/L	0.320	0.004*		0.272	0.015*
YKL-40, ng/mL				0.319	0.004*
Pleural effusion
Glucose, mg/dL	0.039	0.732		–0.232	0.038*
Protein, g/dL	–0.152	0.177		0.529	<.001*
Albumin, g/dL	–0.379	0.001*		0.433	0.001*
LDH, U/L	0.000	1		0.375	0.001*
Triglyseride, mg/dL	–0.001	0.992		0.388	<0.001*
Cholesterol, mg/dL	–0.195	0.084		0.525	<0.001*
ADA, UI/mL	0.074	0.512		–0.027	0.814
Leucocyte, ×103/mL	–0.313	0.005*		0.028	0.805
Neutrophils, %	–0.156	0.250		0.048	0.725
Lymphocytes, %	0.098	0.478		0.382	0.006*

*, P values <0.05 were accepted as significant, Spearman’s correlation test was used for analysis; ADA, adenosine deaminase.