Endocrine System Testing
Endocrine System Testing in Our Raleigh and Durham, NC Clinics
The female menstrual cycle is under the hormonal control of the endocrine system. This is a complex system of hormone signals and actions that involves the hypothalamus and pituitary gland, as well as the ovaries.
Follicle Stimulating Hormone and Luteinizing Hormone
The hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH).
FSH and LH stimulate follicle production in the ovary. The hormones released by the ovary, such as estradiol, will eventually trigger a marked release of LH. This is known as the “LH surge.” This rise in LH will stimulate the rupture of the ovarian follicle and release of the oocyte into the abdominal cavity.
Women who are beyond the reproductive years or who have diminished ovarian function will lack the rise in estradiol and their FSH and LH will remain elevated. FSH is usually tested on day three of the menstrual cycle as an indicator of ovarian function.
Endocrine system testing at our Raleigh and Durham, NC clinics is not necessary in everyone. Your physician will advise you if you need this test.
LH usually does not last very long in circulation and is therefore generally not tested. For more information about LH testing, see Ovulation Assessment.
Prolactin
Prolactin is another hormone of the endocrine system that is released from the pituitary gland. For information about endocrine system testing for prolactin levels, see Ovulation Assessment.
Androgens
Androgens are a group of hormones usually thought of as male hormones — for example, testosterone is an androgen. But these hormones are also present in females.
There are several disorders in which the androgens are abnormally elevated in a female patient. Physical findings usually include abnormal hair growth, acne, and deepening of the voice.
Effects of increased androgen levels are commonly seen in polycystic ovarian syndrome.
Progesterone
Presence of a progesterone in the blood on day 21 — or approximately seven days after the date of suspected ovulation — can be an indicator of ovulatory function.
A level greater than eight usually indicates ovulation has occurred and adequate progesterone is being made to support an early pregnancy.
For information about testing for 17-OH progesterone, see Ovulation Assessment.
Thyroid-Stimulating Hormone (TSH)
Thyroid-stimulating hormone (TSH) is released from the pituitary gland and stimulates the thyroid gland to make thyroid hormones. Like the thyroid exam, the TSH blood test may uncover a thyroid abnormality that may have an impact on fertility.
An elevated level means the gland is not making enough hormones, as in the case of hypothyroidism. Low levels indicate problems with TSH production or increased thyroid hormone production, known as hyperthyroidism.
Additional tests may be necessary to determine the exact cause of the abnormality, which can be much more complex than presented here.
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