To investigate effect of the soluble epidermal growth factor receptor （sEGFR/sErbB1） level in the periph-eral blood in development

invasiveness

apoplexy of each type of pituitary tumor. Methods The sEGFR level was determined in peripheral serum from 190 patients with pituitary diseases by enzyme linked immunosobent assay. The sEGFR levels were measured in 10 pituitary Rathke’s pouch

18 pituitary hyperplasia

161 pituitary adenomas including 30 microadenomas

83 large adenomas

48 giant adenomas

1 pituitary carcinoma

and 28 hea-lthy controls. Results In the patients with pituitary hyperplasia

microadenoma

large adenoma

giant adenoma

and pituitary carci-noma

the sEGFR level was 188.92 ± 32.62

209.83 ± 19.01

333.20 ± 69.33

405.85 ± 37.38

and 617.45 fmol/mL indepen-dently. They were all significantly higher than patients with pituitary Rathke’s pouch （156.78 ± 18.24 fmol/mL

P < 0.001） and healthy control group （159.11 ± 40.50 fmol/mL

P < 0.05）. The sEGFR level in pituitary carcinoma was higher than pi-tuitary adenoma. In patients with pituitary adenoma

the sEGFR level was positive correlated to the size of pituitary adeno-mas （r = 0.998）

the significant difference was observed for the sEGFR level in each group of the patients with pituitary adenomas （P < 0.001）. Furthermore

in patients with pituitary ACTH-secreting microadenomas

the serum sEGFR levels in invasiveness （295.00 ± 77.80 fmol/mL） was higher than that in non-invasiveness （210.60 ± 16.4 fmol/mL

P < 0.05）. In pati-ents with pituitary ACTH-secreting

PRL-secreting

GH-secreting

and non-functioning large adenomas

the serum sEGFR levels in invasiveness （407.86 ± 28.50

399.25 ± 30.10

386.00 ± 13.08

and 369.25 ± 36.70 fmol/mL） was higher than that in non-invasiveness （335.25 ± 63.49

300.64 ± 47.57

297.00 ± 61.93

and 269.30 ± 25.68 fmol/mL） respectively （P < 0.05）. In patients with invasive pituitary PRL-secreting

GH-secreting

and non-functioning giant adenomas

the serum sEGFR levels not significantly different in between invasiveness （417.50 ± 35.94

409.50 ± 69.14

and 417.50 ± 44.13 fmol/mL） and non-invasiveness （386.00 ± 49.64

417.50 ± 44.03

and 409.51 ± 35.17 fmol/mL） （P > 0.05）. In patients with pituitary large adeno-mas

the sEGFR levels in pituitary apoplexy （377.48 ± 39.18 fmol/mL） was higher than that in non-pituitary apoplexy （343.18 ± 68.17 fmol/mL

P > 0.05）. Conclusions The increased level of peripheral serum sEGFR is concomitant with development

proliferous size of the adenomas in patients with pituitary adenomas. In addition

the elevated levels of serum sEGFR occur in pituitary apoplexy as clinical active tumors

and the non-invasive ACTH secreting adenomas. The sEGFR levels could be differen-tiated helpfully between pituitary adenomas and non-pituitary adenomas. These data suggest that serum sEGFR could be as a referable marker of the size and activation of proliferation in pituitary adenoma.