HomeHealth articleshypothyroidismHow Does Hypothyroidism Affect the Menstrual Cycle?

The Link Between Hypothyroidism and Menstrual Cycle

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Irregular periods can be seen among 20 percent of women having hypothyroidism. Read further to learn more.

Medically reviewed by

Dr. Arpit Varshney

Published At October 9, 2023
Reviewed AtDecember 1, 2023


The menstrual cycle is a natural physiological process occurring in women. One of the reasons for irregularities in the menstrual cycle can be hypothyroidism. Women are ten times more prone to develop hypothyroidism than men. Underactive thyroid is a condition in which the thyroid gland produces fewer thyroid hormones and is known as hypothyroidism.

What Is Hypothyroidism?

The thyroid is a small gland situated at the front of the neck. Triiodothyronine (T3) and thyroxine (T4) are the two important hormones the thyroid gland produces. They help in maintaining the whole body system to work properly. They travel throughout the body and regulate body weight, metabolism, and brain development. The underactive thyroid gland is responsible for hypothyroidism. Five percent of people suffer from this condition; women are generally affected more than men. In a few people, it goes undiagnosed.

What Are the Causes of Hypothyroidism?

Reasons for the causes of hypothyroidism are as follows:

  • Hormone Deficiency: When T3 and T4 production is not sufficient, hypothyroidism can be caused.

  • Iodine Deficiency: Malnutrition and iodine deficiency due to the intake of a diet that does not contain enough iodine may lead to hypothyroidism and goiter (enlarged thyroid gland).

  • Autoimmune Disease: Sometimes, even though iodine is present sufficiently in diet, hypothyroidism is caused by an autoimmune disease called Hashimoto’s disease (occurs when the body makes antibodies and they attack the thyroid gland). In this condition, the immune system attacks the thyroid gland, affecting its functions.

  • Physical or Medical Damage to the Thyroid Gland: Physical damage occurs due to treatments like surgery or radiation received while treating hyperthyroidism or other reasons. Some medications, like Lithium, have side effects on the thyroid gland and may lead to hypothyroidism.

  • Pregnancy: After pregnancy, a disorder called postpartum thyroiditis may be developed. This disorder occurs in seven in a hundred pregnancies.

What Are the Symptoms of Hypothyroidism?

Symptoms of hypothyroidism include

1) Weight Gain: People tend to gain 5 to 10 pounds, and this unexplained weight gain in hypothyroidism is very common and frustrating to patients. Some studies have also observed a ten percent increase in weight gain. Most of the weight gain is due to water and salt retention in the body. Another reason is increased fat. This happens due to a slowdown of metabolism.

2) Tiredness and Feeling Cold: General symptoms of hypothyroidism are tiredness (fatigue) and feeling cold. Forty percent of people affected experience tiredness, and fifty percent experience cold. These symptoms get worse as hypothyroidism worsens. When thyroid hormones decrease, metabolism decreases and leads to tiredness and cold.

3) Hair Loss: Half of all people affected with hypothyroidism show hair loss. It is partial or extensive loss of hair that may be seen. Few of the women involved may show loss of outer eyebrows (madarosis). Hair may become dry, brittle, and coarse, taking longer to grow. Nails are also affected as hair. They also show brittleness and become thick and also grow slowly.

4) Dry Skin and Other Skin Changes: Skin become thinner and scaly leading to dry skin. Dry skin is seen in arms, legs, above the joints, palms, and soles too. In severe hypothyroidism, myxedema can be observed. Myxedema is when the skin gets swollen due to sugar buildup. Confusion and heart and lung problems may also develop.

5) Infertility and Subfertility: 24 percent of women affected by hypothyroidism could not conceive after one year. Low thyroid levels contribute to infertility as thyroid hormones are involved in reproduction. When fertility is affected following symptoms can be observed:

  • Affecting regular ovulation (release of egg in menstruation).

  • Irregular menstrual cycles.

  • Increased risk of miscarriage.

6) Irregular Periods: Thyroid hormones T3 and T4 are involved in the reproductive system. Hence irregular menstrual cycles (heavy or infrequent periods) can be seen in 20 percent of women with hypothyroidism.Severity increases the risk of irregularities in menstrual cycles. Hypothyroidism may also lead to amenorrhea (no periods at all).

7) Sexual Dysfunction: A problem in the desire for or enjoyment of sex is called sexual dysfunction. About 46 percent of women affected with hypothyroidism experience sexual dysfunction.

8) Depression and Mood Change: Depression and other mood disorders, including anxiety, can be observed in hypothyroidism. About 60 percent of women experience depression. Women are more prone than men to experiencing depression and anxiety. Other symptoms include the following:

  • Difficulty in concentrating.

  • Poor memory.

  • Slow thinking.

Studies showed that metabolic changes occur in the brain and affect neurotransmitter levels associated with depression.

9) Constipation: Low thyroid levels slow down the metabolism leading to slow metabolism in the gut also. This results in constipation. Twenty percent of people affected with hypothyroidism experience constipation.

10) Muscle Weakness and Cramps: 80 percent of people experience muscle weakness. Thyroid hormones are involved in the functioning of muscles. Since low thyroid hormones in hypothyroidism are present, muscle functioning is affected.

How Does Hypothyroidism Affect the Menstrual Cycle?

The thyroid is known as the powerhouse as it regulates metabolisms of the body and many important processes like blood pressure, heart rate, temperature, and tissue development. Endocrine glands affect almost all organs of the body as they produce hormones. If one gland is not working correctly, it may result in disruption to the whole system of the body.

The interconnection of the hypothalamus, pituitary, and ovaries regulates the reproductive system. The thyroid also has a role in regulating the reproductive system. Deficient levels of thyroid hormones result in the production of more thyroid-stimulating hormone (TSH) and prolactin by the pituitary gland.

Prolactin plays a role in supporting ovulation. When prolactin levels increase, it affects the ovaries, which produce estrogen and progesterone, inhibiting ovulation and becoming a reason to skip periods. This change is due to thinning of the uterine lining and changes in the pituitary gland.

Hypothyroidism may lead to heavy bleeding. Some women, who show uncontrolled hypothyroidism, may exhibit disordered growth and shed of the uterine lining, leading to heavy bleeding. Generally, severe hypothyroidism causes more irregular menstrual cycles than mild hypothyroidism.

Estrogen is a sex hormone responsible for controlling and growth of the uterine lining in the first half of the menstrual cycle till ovulation occurs. The release of the egg is called ovulation. When the egg is released, it leaves a sac producing progesterone. This helps in fertilization and also stabilizes estrogen. Increased levels of estrogen and decreased levels of progesterone result in heavy bleeding.

How to Diagnose Hypothyroidism?

A blood test assesses thyroid function to determine thyroid-stimulating hormone (TSH) levels, T3, T4, and thyroid peroxidase (TPO) antibodies. Generally, Increased TSH and decreased T4 levels tell about hypothyroidism. TPO antibodies may or may not be present. If present indicates an autoimmune condition like Hashimoto’s is the cause of hypothyroidism.

What Is the Treatment for Hypothyroidism?

Medications: The first step to treat hypothyroidism is to be given medications. The correct dosage of medications will be determined over time, depending on the hormone levels in the blood.

Hormone Replacement Therapy: Hormone replacement therapy treats the condition by optimizing hormones.

Lifestyle: Adopting a healthy lifestyle helps in the treatment of hypothyroidism.

Diet and Exercise: Eating healthy food and regular exercise help treat hypothyroidism and overall health.


Thyroid hormone levels affect the menstrual cycle because they are associated with female sex hormones. A diet, exercise, and maintaining stress levels greatly impact regulating the thyroid gland. Knowing about hypothyroidism in detail helps one to know the symptoms and helps in the early diagnosis of the condition. Early diagnosis is always good for effective treatment to be accomplished.

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Dr. Arpit Varshney
Dr. Arpit Varshney

General Medicine


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