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Endocrine Function

The endocrine system refers to the collection of glands that secrete hormones directly into the circulatory system to be carried towards distant target organs. Most hormones work through interactions with the brain and have either a direct or indirect influence on each other.


The main glands involved in hormone secretion and activity include: the hypothalamus (gland at the base of the brain), pituitary (gland in the middle of the brain), gonads (ovaries and testes), adrenals (glands located above the kidneys), and thyroid gland (located beneath the voicebox), as well as the pancreas and liver . Testing for individual hormone levels that are produced by various hormone-producing glands can identify irregularities that can produce negative effects on menstrual and reproductive function. The endocrine system is vital for reproductive health.

Without proper endocrine function, our bodies cannot maintain proper hormonal balance.

The health of our endocrine system is essential to our ability to function properly. Our cells are genetically programmed to only receive and respond to messages from certain hormones. Hormone levels can be influenced by stress, fluid changes in the body, minerals in the blood and infection. Each endocrine gland plays a specific role in the ability of our body to maintain proper function. Each endocrine gland also communicates with the other in an amazing design. If one of the endocrine glands is not functioning properly, it may cause a broken link in communication with other endocrine glands or actions of the body, which may greatly impair fertility. Because the endocrine glands secrete hormones, and the hormones are messengers for actions within the body, if the gland is not functioning properly, hormonal imbalance occurs and the ability to reproduce may be impaired.

Endocrine Function Fertility Tests

ACTH (Adrenocorticotropic Hormone): Too much ACTH can result from congenital (a medical condition present at birth) adrenal hyperplasia (CAH ), the enlargement of the adrenal glands. CAH results from inadequate production of glucocorticoids (a class of hormones produced by the adrenal gland). Glucocorticoid precursors accumulate in these persons and are converted to androgenic steroids. These androgenic steroids can lead to infertility. Male hormones produced by the adrenal gland (called androgens) which, when found in excess, may lead to fertility problems in both men and women. Excess androgens in the woman may lead to the formation of male secondary sex characteristics and the suppression of LH and FSH production by the pituitary gland. Elevated levels of androgens may be found in women with polycystic ovaries, or with a tumor in the pituitary gland, adrenal gland, or ovary. May also be associated with excess prolactin levels.

Aldosterone: A hormone in the blood made by the adrenal glands that helps regulate sodium and potassium levels. More specifically, it helps control blood pressure and the balance of fluids and electrolytes in the blood. M easuring the amount of aldosterone released into the body by the adrenal glands can identify a tumor in the adrenal glands, find the cause of high blood pressure or low potassium levels.

C-Peptide: C-peptide can serve as a valuable index to insulin secretion. Low C-peptide levels are expected when insulin secretion is diminished, as in insulin dependent diabetes, or suppressed, as a normal response to exogenous insulin; whereas elevated C-peptide levels may result from the increased ß-cell activity observed in insulinomas. C-peptide determination can be used to supplement insulin measurements as an index to pancreatic activity in the differential diagnosis of hypoglycemia.

CA-125 : A protein found on the surface of many ovarian cancer cells and small amounts of normal tissue. The test measures the amount of CA-125 in the blood. It may be used for women with an ovarian cyst, to help identify endometriosis or to track the progression of endometriosis.

Cortisol: Known as the stress hormone because it is produced in response to stress. As an indicator of adrenocortical function, measurement of blood cortisol level is useful in the differential diagnosis of Addison’s and Cushing disease, hypopituitarism, adrenal hyperplasia and carcinoma. Abnormal cortisol concentrations have been shown to exist in patients with acute infections, severe pain, diabetes mellitus or heart failure, and in women either pregnant or on estrogen therapy.

Growth Hormone: Typically ordered for patients with symptoms of growth hormone abnormalities, as a follow-up to other abnormal hormone test results, or to help evaluate pituitary function. GH is made by the pituitary gland and plays an important role in how the body uses food for energy (metabolism). Growth hormone is also an insulin antagonist (inhibits insulin and its sugar level lowering effects) that, in susceptible individuals, can lead to elevated sugar levels in the blood and diabetes mellitus.

Insulin: Like Growth Factor Binding Protein 1 (IGFBP-1) – the production of IGFBP-1 is suppressed by high insulin levels (hyperinsulinemia), leading to an increase in free IGF-1. IGF-1 works with insulin to exacerbate hyperandrogenism (over production of male hormones) by increasing testosterone production in the ovaries. Thus, a combination of hyperinsulinemia, elevated free IGF-1 and elevated androgens found when low levels of IGFBP-1 are present likely contribute to the endometrial dysfunction, infertility, increased miscarriage rate and endometrial hyperplasia seen in PCOS.

T3 (Triodothyronine): A blood test that checks proper thyroid function. Thyroid disorders may affect ovulation. T3 levels distinguish clearly between normal and hyperthyroid (over production of thyroid hormone) patients, since it is elevated in the latter. Thyrotoxicosis may be caused by abnormally high concentrations of T3 rather than T4. The levels of serum T4 (Thyroxin), TBG (Thyroxin Binding Globulin), TSH (Thyroid Stimulating Hormone) and other clinical findings are also used to determine an individual’s thyroid status

T4 (Thryroxine): A blood test that checks proper thyroid and pituitary function. Thyroid disorders may affect ovulation. T4 (or Thyroxin) is the principal thyroid hormone that circulates almost entirely bound to other (carrier) proteins, chief of which is thyroxin-binding globulin (TBG). Given normal levels of thyroid-binding proteins, hyperthyroidism (over production of thyroid hormone) is characterized by increased levels of T4. Hypothyroidism (too little production of thyroid hormone) is indicated by decreased levels of T4. However, abnormal TBG levels may affect the ability of the total T4 concentration to determine thyroid status (either hyperthyroidism or hypothyroidism). An estimate of the level of circulating TBG may be determined by doing a T3 Uptake test. In disorders of thyroid function, the total T4 and T3 uptake values will both be either high or low. In normal thyroid patients with abnormal TBG levels the total T4 and T3 Uptake will deviate in opposite directions (one will be high and the other low or vice versa). The total of the T4 and the T3 Uptake values, divided by 100, is known as the Free Thyroxine Index (FTI or T7), a widely used indicator of thyroid status.

TSH (Thyroid Stimulating Hormone): Stimulates the thyroid gland to produce T4 and T3. Measurement of TSH is used primarily to determine the cause of hypothyroidism (too little thyroid production). In primary hypothyroidism, the TSH level is elevated due to impaired production of thyroid hormones. In secondary or tertiary hyperthyroidism, thyroid hormone production is low due to pituitary or hypothalamic lesions. In hyperthyroidism (too much thyroid production), the TSH level is typically suppressed to subnormal levels. TSH can also be used to help determine if a patient has adequate levels of T4.

Thyroid Peroxidase (TPO Ab): Detects autoantibodies directed against thyroid peroxidase (TPO), an enzyme in the thyroid gland that is very important to the production of thyroid hormones. Autoantibodies to thyroid peroxidase are produced by the body itself. TPOAb can attack the thyroid and damage thyroid function. A positive test for these antibodies prior to receiving fertility treatment indicates an increased risk for miscarriage.

Vitamin D 25OH: The most accurate measure of the amount of vitamin D in the body. Low 25-hydroxy vitamin D levels indicate a deficiency in vitamin D that may lead to low blood calcium levels (hypocalcemia), thin or weak bones (osteoporosis and osteomalacia), and high levels of parathyroid hormone (secondary hyperparathyroidism) Vitamin D is also associated with infertility because it supports production of estrogen in men and women. Inadequate vitamin D levels are also associated with an elevated risk of pre-eclampsia (high blood pressure that develops in some women during the last half of pregnancy).

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