Table 2.

The detailed data about levels of pre- and postoperative serum serotonin.

	Serum serotonin (ng/mL)
	Pre-operation	Post-operation	P value
Surgery
Laminectomy & discectomy	3.59 ± 1.11	3.62 ± 0.94	.84
Laminectomy & discectomy	3.19 ± 1.39	3.56 ± 1.58	.07
Gender
Male	3.36 ± 1.05	3.79 ± 1.24	.03
Female	3.37 ± 1.41	3.46 ± 1.37	.59
Age
< 50 yrs/old	3.77 ± 1.18	3.77 ± 1.33	.97
> 50 yrs/old	2.62 ± 1.11	3.23 ± 1.27	.005
Current cigarette smoker
Yes	3.66 ± 0.82	4.17 ± 1.09	.1
No	3.32 ± 1.34	3.48 ± 1.34	.25
Current opium addict
Yes	3.29 ± 1.17	3.34 ± 1.13	.63
No	3.38 ± 1.3	3.61 ± 1.35	.1

Data are shown as mean ± standard deviation.