what is follicle
A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. FSH is produced by the pituitary gland. 1  In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. follicle-stimulating hormone (FSH) test may be done to: 1  Help find the cause of infertility. 2  FSH testing is commonly used to help evaluate a: 3  Woman's egg supply (ovarian reserve). 4  Man's low sperm count. 5  Help evaluate menstrual problems, such as irregular or absent menstrual periods (amenorrhea).