Do You Have PCOS or Thyroid Disease?

Two different endocrine disorders share similar symptoms

Female doctor checking patient's neck
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When investigating the cause of missed or absent periods accompanied by weight gain and/or abnormal hair growth or loss, doctors will often focus their attention on two diseases associated with hormonal irregularities: polycystic ovary syndrome (PCOS) and thyroid disease.

Both of these conditions share many of the same symptoms. PCOS occurs when a woman's ovaries or adrenal glands produce an excessive amount of male hormones. Thyroid disease, by contrast, is characterized by either the excessive production of thyroid hormones (hyperthyroidism) or an abnormally decreased production of thyroid hormones (hypothyroidism).

Polycystic Ovary Syndrome (PCOS)

PCOS is a hormonal disorder common among women of reproductive age. Women with PCOS will often have abnormal periods or experience symptoms related to elevated levels of male hormones (androgens). The ovaries themselves will often develop numerous, fluid-filled cysts and fail to regularly release eggs during the ovulation cycle.

The exact cause of PCOS remains unknown. Symptoms are diverse and may include:

  • Irregular or no menstrual periods
  • Excessive facial or body hair (hirsutism)
  • Acne
  • Pelvic pain
  • Infertility
  • Weight gain
  • Insulin resistance
  • Sleep apnea
  • Patches of thick, darkened, velvety skin

There is no single test used to confirm PCOS. Diagnosis is made based on a review of symptoms and diagnostic tests. PCOS is treated symptomatically with a focus on reducing insulin resistance, restoring fertility, treating hair or skin abnormalities, and regulating menstrual cycles.


The pituitary gland produces a hormone called thyroid stimulating hormone (TSH) which triggers the secretion of hormones from the thyroid gland.

These thyroid hormones, known as T3 and T4, regulate our body's metabolism, body temperature, and heart rate. The excessive production of these hormones is known as hyperthyroidism, the condition of which is associated with, among other things, thyroid cancer and an autoimmune disorder known as Graves disease.

Symptoms may include: 

  • An enlarged thyroid gland
  • Missed or absent menstruation
  • Weight loss despite an increase in appetite
  • Excessive sweating
  • Heat intolerance
  • Hair loss characterized by a fineness of texture
  • Protrusion of the eyeballs (proptosis)
  • Increased heart rate and blood pressure
  • Insomnia

Diagnosis is made by testing TSH and T3/T4 levels. Treatment may involve the use of medications to temper hormonal production (propylthiouracil, methimazole), radioactive iodine pills to shrink thyroid tissue or the surgical removal of the thyroid gland accompanied by hormone replacement therapy.


Hypothyroidism occurs when there is an inadequate production of T3 and T4. In primary hypothyroidism, decreased hormone levels are caused by problems with the thyroid gland itself. Secondary hypothyroidism is associated with problems in the pituitary gland.

Hypothyroidism can be caused by thyroid cancer, cancer surgery, or an autoimmune disorder known as Hashimoto’s disease. Symptoms may include:

  • Cold intolerance
  • Fatigue and lethargy
  • Irregular or infrequent menstruation 
  • Heavy or prolonged menstrual bleeding
  • Decreased libido
  • Weight gain despite decreased appetite
  • Constipation
  • Coarse, dry skin

Hypothyroidism is diagnosed with the same lab tests as hyperthyroidism. Hormone replacement therapy is usually the first line of treatment, most often using the drug levothyroxine (Synthroid, Levothroid).

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View Article Sources
  • Gaberscek, S.; Zaletel, K.; Shwetz, V. et al. "Mechanisms in Endocrinology: Thyroid and polycystic ovary syndrome." Eur J Endocrin. 2015; 172: R9-R21.
  • McCance, K. and Huether, S. (2016) Understanding Pathophysiology (Sixth Edition)St. Louis, Missouri: Mosby.