How Hypothyroidism and Amenorrhea are Related

How Hypothyroidism and Amenorrhea are Related

A number of menstrual cycle abnormalities can be attributed to dysfunctions of the thyroid gland.  According to research, menorrhagia is the most common menstrual abnormality associated with sub-clinical and overt hypothyroidism.  However, a study of adult women who developed amenorrhea found abnormal levels of prolactin in 7.5% of them whilst abnormal levels of TSH were detected in 4.2%.  These are both symptomatic of hypothyroidism and indicate that, although relatively uncommon in comparison to menorrhagia, there is nevertheless a link between hypothyroidism and amenorrhea.

What Is Menorrhagia?

Menorrhagia is characterized by abnormally high uterine bleeding.  Whilst many women do suffer from heavy bleeding during their menstrual cycle, a diagnosis of menorrhagia is generally reserved for cases where at least twice the normal amount of blood is lost.  As mentioned previously, menorrhagia is commonly associated with hypothyroidism and may occur with both sub-clinical and overt hypothyroidism.

Interesting Questions about Thyroid:

Radioactive Iodine

How does radioactive iodine work?

The thyroid gland absorbs iodine from the blood. When radioactive iodine enters your thyroid, it slowly shrinks the gland over a period of weeks or months.

The treatment is safe, simple, convenient, and inexpensive. It is usually given only once, rarely causes any pain or swelling, and does not increase the risk of cancer. However, it must be avoided during pregnancy or nursing, and patients should not become pregnant for at least six months after treatment.

When is radioactive iodine used?

Radioactive iodine is the most common treatment for hyperthyroidism. It does not require hospitalization. About 90% of patients need only one treatment. They usually start getting better in three to six weeks, and most are cured within six months.

This treatment may also be used after surgery for certain thyroid cancers. Radioactive iodine dissolves any cancerous tissue that could not be removed by surgery. The dose of radioactive iodine is larger in this case, and patients usually stay in the hospital for a day or two.

What can be expected with radioactive iodine treatment for hyperthyroidism?

  • It is usually given in liquid form or as a capsule. The dose can range from 4 to 29 millicuries.
  • It is tasteless.
  • There are almost never any side effects. In some rare cases, there can be an inflammation of the thyroid gland causing a sore throat and discomfort.
  • Radioactive iodine not taken up by the thyroid gland is excreted in urine and saliva. There is no evidence that the small amount of I131 excreted in the urine and saliva is harmful. Nonetheless, prudent nuclear medicine experts have recommended a wide variety of precautions. While these recommendations are sometimes confusing and inconsistent, it may be appropriate to take a few simple measures to avoid unnecessary exposure of infants and children to I131. Treated patients should rinse out their glasses or cups and eating utensils immediately after drinking and eating. The toilet should be flushed immediately after use, and the rim of the bowl should be wiped dry, if necessary.
  • It is advisable to drink two to three extra glasses of water a day during the four- to seven- day period following radioactive treatment so that radioactive material will not collect in the bladder for a long period of time.
  • Because radioactive iodine passes into breast milk, breast feeding mothers are asked to wean their babies before treatment.
  • It typically takes six weeks before thyroid hormone production is noticeably reduced. The average length of time for the thyroid hormone levels to become normal is about three to four months. If thyroid levels are not considerably reduced six months after treatment, the doctor might suggest repeating the treatment. Ninety percent of the time only one treatment is required; however, it might take as many as three attempts. The patient could be advised to take beta-blocking drugs and other medications the doctor believes are necessary until normal thyroid hormone production is restored.
  • Many patients treated with radioactive iodine become hypothyroid. This may happen within weeks, months, or years of treatment. Therefore, patients should be aware of the signs and symptoms of hypothyroidism, and their physicians should monitor their thyroid hormone levels regularly. When the patient becomes hypothyroid, thyroid hormone replacement begins and continues for life-one pill a day.
Thyroid Hormone Pills

When are thyroid hormone pills used?

Thyroid hormone pills provide the body with the right amount of thyroid hormone when the gland is not able to produce enough by itself. The pills are frequently needed after surgery or radioactive iodine therapy.

Thyroid hormone tablets are the standard treatment for hypothyroidism. While symptoms usually get better within a few months, most patients must take the pills for the rest of their lives. This is especially true for hypothyroidism caused by Hashimoto’s thyroiditis or radioactive iodine treatment.

If the entire thyroid gland has been surgically removed, thyroid hormone tablets replace the body’s own source of the hormone. If only a part of the gland has been removed, the pills may keep the remaining gland from working too hard. This decreases the chance that the thyroid gland will grow back.

How much hormone do I need?

The preferred hormone for treatment is levothyroxine (T4). You should use only the brand-name that your doctor prescribes, since generic brands may not be as reliable. Name-brand levothyroxine pills include Synthroid®, Levoxyl®, Levothroid®, Euthyrox®, and Eltroxin®.

Patients sometimes take more pills than they should, trying to speed up the treatment or lose weight. However, this can lead to hyperthyroidism and long term complications, such as osteoporosis. You should take the pills as your doctor prescribes.

At different times in your life, you may need to take different amounts of thyroid hormone. Therefore, you should see your doctor at least once a year to make sure everything is all right.

® Synthroid is a registered trademark of Knoll Pharmaceuticals.
® Levoxyl is a registered trademark of Jones Medical Industries.
® Levothroid is a registered trademark of Forest Pharmaceuticals.
® Euthyrox is a registered trademark of EM Pharma.
® Eltroxin is a registered trademark of Roberts Pharmaceuticals.

Are thyroid hormone pills needed after treatment for hyperthyroidism?
Many patients treated for hyperthyroidism become hypothyroid. They will need to take thyroid hormone pills for the rest of their lives. In addition, they will need to see their doctor at least once a year.

What are the Facts for People Given Radiation (X-ray) Treatments as Children?

Between one and two million Americans received radiation treatments in childhood or adolescence between 1920 and 1960. The most common reasons for these treatments were:

  • enlarged thymus gland
  • acne
  • ringworm
  • enlarged tonsils and adenoids
  • various chest conditions

The risk factor for developing thyroid cancer if you had childhood radiation treatments is between 2% and 7% as compared to .004% in the general population.

There have been cases of side effects from radiation treatments (not radioactive iodine treatments) reported as long as 45 years after treatment.

Most physicians agree that the thyroid gland of these patients should be checked annually.

Some physicians rely solely on physical (manual) examination of patients treated as children with radiation. Others prefer to perform scans or ultrasounds for nodules too small to detect manually that might be cancerous.

A person treated as a child with radiation can request that their medical records be sent to them by writing the hospital or clinic where they had the treatments. Ask for a record of how much each dose of radiation was as well as how often and over what period of time treatments were given.

Have more questions? Need more answers? Check our Full Thyroid FAQ

What Is Amenorrhea?

Amenorrhea can be either primary or secondary and it affects up to 3 – 4% of womenPrimary amenorrhea is the failure of menstruation to occur by the age of 16.  The 2 main causes of primary amenorrhea are:

  • genetic and chromosomal abnormalities (absence of a uterus, Turner Syndrome etc)
  • hormonal problems caused by hypothalamus or pituitary gland disorders, which in turn can be brought on by over exercise, eating disorders and/or psychological and physical stress.

Secondary amenorrhea is missing consecutive periods after regular menstruation has commenced.  Typical candidates for a diagnosis of secondary amenorrhea are those with hitherto regular cycles who have missed 3 periods in a row or haven’t had a period for 6 months.  For those  with irregular cycles, it’s absence of a period for 12 months.  Secondary amenorrhea has a number of causes, the most obvious of which is pregnancy.  Other than pregnancy, other causes of secondary amenorrhea include:

  • breast feeding
  • menopause
  • eating disorders – anorexia nervosa
  • putting on, or losing, excessive amounts of weight
  • stress, particularly severe long term stress
  • some types of therapies – chemotherapy, radiation treatment
  • some medications – contraceptives (pills, injectables, hormonal IUDs), antidepressants, blood pressure meds etc
  • scar tissue in the uterine lining caused by procedures like a cesarean, C and R or uterine fibroid treatment
  • irregularities in the hypothalamus gland that cause it to reduce or stop producing the hormone gonadotrophin releasing hormone (GnRH) that triggers each menstrual cycle.  This type of amenorrhea is called hypothalamic amenorrhea.
  • tumors in the pituitary gland
  • fragile X-associated primary ovarian insufficiency (FXPOI).
  • polycystic ovary syndrome (PCOS)
  • thyroid disorders – hypothyroidism, hyperthyroidism

Hypothyroidism And Amenorrhea – Their Relationship

Ovarian cycles in most female mammals, including humans, is a finely balanced interchange between several hormones.  The maturation of eggs, and the production of estrogen, within the follicle is stimulated by an anterior pituitary gland hormone called follicle stimulating hormone (FSH).  As estrogen levels rise, the anterior pituitary switches off production of FSH and begins producing more luteinizing hormone (LH).  LH triggers ovulation, which is the release of the egg from the follicle, and stimulates the development of the corpus luteum, a body of cells that will produce the progesterone needed to sustain a pregnancy during the early stages.

How is this process related to the thyroid?

When blood levels of both types of thyroid hormones (T3 and T4) drop, the hypothalamus produces TRH (thyrotropin releasing hormone).  TRH’s primary role is regulating the production of TSH (thyroid stimulating hormone) and prolactin in the pituitary gland.  When TRH levels rise, the pituitary responds by stepping up production of TSH and prolactin.  High levels of prolactin then inhibits the production of GnRH (gonadotrophin releasing hormone) by the hypothalamus.  GnRH is responsible for signalling the pituitary to produce FSH….

So it’s a cascading effect.  When blood levels of thyroid hormones drop it sets in motion a series of hormonal activities beginning right at the very top of the command chain with the hypothalamus.  Low levels of thyroid hormones triggers a rise in TRH (hypothalamus), which triggers a rise in TSH and prolactin (pituitary).  A rise in prolactin reduces production of GnRH (hypothalamus), which results in a drop in FSH (anterior pituitary) and a subsequent drop in LH (anterior pituitary).  FSH and LH are the two hormones that control the ovarian cycle.  Without these 2 hormones, or without enough of them, follicle maturation and ovulation cease causing amenorrhea.

Treating Hypothyroidism And Amenorrhea

Normally by the time thyroid hormone production is affected enough to cause amenorrhea, other symptoms of hypothyroidism will have become apparent.  Sub-clinical hypothyroidism tends to be associated more with menorrhagia.

Because amenorrhea can be caused by a range of things, ascertaining the underlying cause is usually the first step in treating it.   Pregnancy, the most obvious cause, needs to be ruled out first.  If the patient isn’t pregnant, the next step is usually testing levels of TSH, LH, FSH and prolactin.  A test result showing high levels of TSH but normal levels of the other 3 hormones generally indicates the amenorrhea has been caused by hypothyroidism.  In which case, further tests confirming the levels of thyroid hormone will be ordered and treatment started accordingly.  Usually, treatment of the underlying hypothyroidism will restore normal ovarian activity after several months.