Table 2. Correlation between clinical features and the expression of S100A9 in 80 pituitary adenomas.

Characteristics	Knosp grade		P
	0 and I	II, III, and IV
Age(years)	19(≥45)		0.103
	17(<45)
		27(≥45)	0.083
		17(<45)
Gender	20(Male)		0.319
	16(Female)
		23(Male)	0.452
		21(Female)
Hormone secretion subtype	15(Non-function)		0.176
	21(Function)
		26(Non-function)	0.194
		18(Function)
	9(PRL)		0.097
	7(GH)
	5(ACTH)
		7(PRL)
		8(GH)	0.115
		3(ACTH)

In order to avoid the different expression of S100A9 in IPA and non-invasive pituitary adenomas, clinical samples were divided into Knosp grade 0 and I, or Knosp grade II, III, IV. The expression of S100A9 in different ages, genders and hormone secretion subtypes were analyzed, respectively.