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It is indispensable for reproduction and the menstrual cycle. But what exactly characterizes this hormone, and what happens when there is a deficiency? Read on to learn more about the function of progesterone, as well as the symptoms and treatment of a deficiency.

Table of Contents

• What is progesterone?
• What is the function of progesterone?
• What is a progesterone deficiency?
• What are the causes of a progesterone deficiency?
• What are the symptoms of a progesterone deficiency?
• What is premenstrual syndrome (PMS)?
• What are the consequences of a progesterone deficiency?
• How is a progesterone deficiency diagnosed?
• How is a progesterone deficiency treated?
• Summary

What is progesterone?

Progesterone is a steroid hormone that acts as a messenger in the body and regulates various functions. It belongs to the group of sex hormones and is often referred to as the “female hormone,” although it is present in both men and women. However, it plays an indispensable role in the female reproductive system by regulating the menstrual cycle and pregnancy. The main source of progesterone in the female body is the ovaries, specifically the corpus luteum, which forms in the ovaries after ovulation. Smaller amounts are also produced in the adrenal glands and, during pregnancy, in the placenta (Britannica, 2023). 

What is the function of progesterone?

The functions of progesterone are diverse and affect various aspects of women's health:

• Regulation of the menstrual cycle: Progesterone prepares the body for a possible pregnancy by thickening the uterine lining after ovulation. It creates a favorable environment for the implantation and development of a fertilized egg. If fertilization does not occur, progesterone levels drop and menstruation begins.

• Support of pregnancy: If fertilization is successful, progesterone levels remain high to maintain the uterine lining and support pregnancy. Progesterone promotes the growth of blood vessels and glands in the uterine lining.

• Impact on mental health: Progesterone also affects mood and may contribute to the symptoms of premenstrual syndrome (PMS).

• Bone health: Progesterone helps maintain bone density and may reduce the risk of osteoporosis.

Although progesterone is commonly called a “female” hormone, it also plays an important role in the male body, where it is produced in the adrenal glands and testes. It assists in the production of testosterone and other steroid hormones. Additionally, it has a protective function for prostate tissue and influences mood and sleep (Cleveland Clinic, 2022). Curious about your testosterone levels? With our testosterone test, you can easily and quickly test your testosterone level yourself.

How do progesterone and estrogen work together to regulate the menstrual cycle?

Progesterone and estrogen are two crucial hormones that work in harmony in the female body to ensure health and well-being. They play a central role in the menstrual cycle and dominate in different phases. Estrogens dominate the first half of the cycle, preparing the uterine lining for a possible pregnancy. After ovulation, which occurs mid-cycle, progesterone levels rise. If fertilization does not occur, both hormone levels fall, leading to menstruation. A balanced ratio between estrogen and progesterone is essential for a regular cycle and optimal health. Imbalances can cause various health issues, including irregular menstrual cycles (de Mayo et al., 2002).

What is a progesterone deficiency?

A progesterone deficiency, also known medically as luteal phase deficiency or corpus luteum insufficiency, occurs when the body does not produce enough progesterone. This can lead to a wide range of symptoms and significantly impact a woman's health and well-being (Cable & Grider, 2023). 

What are the causes of a progesterone deficiency?

There are many potential causes of progesterone deficiency, affecting both women and men, including:

• Age: As women age, the ovaries' ability to produce progesterone declines. In men, progesterone levels also decrease with age.

• Stress: Cortisol, the stress hormone, can affect progesterone production when present in excess. Cortisol and progesterone share the same precursor—cholesterol. During stress, the body prioritizes cortisol production, which can limit progesterone synthesis. Excessive exercise or restrictive diets may also increase cortisol levels and stress.

• Low cholesterol levels: Cholesterol is essential for making steroid hormones, including progesterone. Low cholesterol may result in low progesterone levels.

• Hypothyroidism: When the thyroid produces insufficient hormones (a condition known as hypothyroidism), it may impair the body's ability to produce enough progesterone.

• Hyperprolactinemia: Prolactin, the hormone responsible for milk production, can interfere with the production of other sex hormones, including progesterone, if produced in excess. This can lead to irregular or absent menstrual cycles.

• Hormonal imbalances: Other imbalances, such as excess estrogen, can result in a relative progesterone deficiency—known as estrogen dominance.

Source: Cleveland Clinic, 2023

What are the symptoms of a progesterone deficiency?

Symptoms of progesterone deficiency can vary and are often nonspecific, making diagnosis difficult. However, some common signs and symptoms include:

• Mood swings, including depression, anxiety, and irritability

• Sleep disturbances or insomnia

• Menstrual problems and irregular cycles

• Headaches or migraines

• Weight gain, especially around the abdomen

• Breast tenderness or discomfort

Source: Caporuscio, 2022

In men, low progesterone can cause symptoms such as low libido, fatigue, weight gain, depression, and gynecomastia (enlarged breast tissue) (Nichols, 2017).

Because the symptoms are nonspecific, it can be difficult to diagnose a progesterone deficiency based solely on clinical presentation. If you suspect a deficiency, consult a doctor or consider a hormone test.

What is premenstrual syndrome (PMS)?

Premenstrual syndrome (PMS) refers to a group of emotional and physical symptoms that many women experience in the days before menstruation. These may include mood swings, irritability, depression, anxiety, bloating, breast tenderness, and fatigue. There is evidence that low progesterone levels may be linked to PMS symptoms (Roomruangwong et al., 2019). 

What are the consequences of a progesterone deficiency?

Women with low progesterone may experience irregular menstrual cycles, have difficulty conceiving, and—if pregnant—be at increased risk of miscarriage or premature birth. The uterine lining, regulated by progesterone, is essential for nourishing the embryo and maintaining pregnancy. Symptoms of low progesterone include abnormal uterine bleeding, irregular periods, spotting, abdominal pain during pregnancy, and recurrent miscarriages. A deficiency can also lead to excess estrogen, which may lower libido, cause weight gain, and lead to gallbladder problems (Endocrine Society, 2022). 

How is a progesterone deficiency diagnosed?

Diagnosis typically begins with a thorough medical history and physical examination. The doctor will ask about symptoms suggestive of a hormone deficiency. A definitive diagnosis requires lab tests, usually involving a blood test at a specific point in the menstrual cycle. The test measures progesterone levels in the blood to determine whether they are within the normal range.

Normal progesterone values vary depending on the phase of the menstrual cycle. In the first half (follicular phase), levels are lower and below 2 ng/mL. After ovulation (luteal phase), levels can rise to 20 ng/mL. In pregnant women, levels are naturally higher and can vary significantly depending on the week of pregnancy. These values may differ slightly depending on the lab and testing method used (University of Rochester Medical Center, 2023). 

In some cases, the doctor may order additional tests to rule out other causes of symptoms. This could include hormone tests, ultrasound of the ovaries, or an examination of the uterine lining (Caporuscio, 2022). 

Want to get an overview yourself?

The women's hormone test from Homed-IQ measures the levels of testosterone, thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and prolactin in your blood. These hormones are essential for ovulation, menstruation, and the production of other hormones. In the context of progesterone deficiency, this test can be particularly useful for identifying hormonal imbalances and providing a foundation for targeted therapy.

How is a progesterone deficiency treated?

Treatment depends on the underlying cause and specific symptoms. Common approaches include:

• Hormone therapy: Progesterone can be administered directly through hormone replacement therapy (HRT), often used in women going through menopause. This helps restore hormonal balance and relieve symptoms such as hot flashes, sleep disorders, and mood swings. HRT may also regulate menstruation or be used to treat certain forms of infertility.

• Lifestyle changes: A nutrient-rich diet with magnesium, zinc, and B vitamins, regular exercise, and stress management can help support hormonal balance.

• Medications: Depending on the cause of the deficiency, medications may be prescribed. In conditions like polycystic ovary syndrome (PCOS)—a common hormonal disorder in women of reproductive age—medications may help regulate the cycle or treat infertility.

It is important to note that hormone therapy is not suitable for everyone and may involve risks. Therefore, it is typically considered only when symptoms are severe and significantly affect quality of life (Healthline, 2016; Cleveland Clinic, 2023 ).

Summary

Progesterone is an essential female sex hormone with many functions. A deficiency can cause various health problems and requires medical treatment. It is important to recognize the signs of a possible deficiency and seek medical advice if there is any suspicion.