The purpose of this study to assess the proliferative effects of erythropoetin on human endometrium tissue by measuring the endometrial thickness, uterine artery and subendometrial blood flow in postmenopausal women.

20 postmenopausal women who are planned to treat with erythropoietin alpha for their renal conditions will be included to the study. Sample size was calculated with proper power analysis with accepting the difference of 1 mm in endometrial thickness as a significant change. After the informed consent, endometrial thickness (mm), uterine artery and subendometrial blood flow by doppler ultrasonography (RI, S/D) will be measured. Same measurements will be repeated on the 3rd day and 30th day. Patients' age, BMI, co-morbidities, administered erythropoietin doses will be noted. No adverse effect is expected with regard to the ultrasonographic examination. Date of the patients who do not attend for the appointments for repetitive examinations and uninterpretable doppler variables due to the atrophic uterus will be noted as the missing data and will be excluded from the study. Proper statistical analysis will be done.

Inclusion Criteria:

• Clinically condition with need for erythropoietin treatment such as anemia due to the renal failure or the need for hemodialysis.
• Must be in postmenopausal period

Exclusion Criteria:

• Patients with any type of malignancy
• Existence of any intracavitary mass which may affect endometrial thickness or blood flow such as endometrial polyps, myomas, intracavitary fluid etc.
• Intrauterine device
• Being on Hormon replacement therapy
• Hysterectomized patients

Patients will be recruited from a tertiary research clinic, department of nephrology, Istanbul, Turkey.