Know Your Blood Parameters: Follicle Stimulating Hormone (FSH)
- Summarised by TGHC Editorial Team
- Aug 9, 2025
- 4 min read
Updated: Dec 23, 2025
Parameter Name
Follicle Stimulating Hormone (FSH)
Follicle Stimulating Hormone (FSH) is a crucial hormone produced by the anterior pituitary gland. It plays a vital role in regulating the reproductive processes in both men and women. In women, FSH is essential for the growth and maturation of ovarian follicles, which are the structures that contain the eggs. In men, FSH is important for the production of sperm and the proper functioning of the testes.
Test Type
Blood
The FSH test is typically performed using a blood sample. This test measures the concentration of FSH in the bloodstream, providing valuable information about the functioning of the pituitary gland and the reproductive system. The blood sample is usually drawn from a vein in the arm and sent to a laboratory for analysis.
Normal Range
Women (Follicular phase): 3.5 – 12.5 IU/L
Women (Mid-cycle peak): 4.7 – 21.5 IU/L
Women (Luteal phase): 1.7 – 7.7 IU/L
Men: 1.5 – 12.4 IU/L
The normal range for FSH levels varies significantly between men and women and also fluctuates during different phases of the menstrual cycle in women. In the follicular phase, which occurs at the beginning of the menstrual cycle, FSH levels are relatively low. Levels rise during the mid-cycle peak to trigger ovulation and then decrease again during the luteal phase. For men, FSH levels remain relatively stable but are still within a specific range that indicates normal testicular function.
High Levels Indicate
Menopause, primary gonadal failure.
Elevated levels of FSH can indicate a variety of conditions. In women, high FSH levels are often associated with menopause, a natural biological process marking the end of a woman's reproductive years. Additionally, high FSH levels may signal primary gonadal failure, meaning the ovaries or testes are not functioning properly. In men, elevated FSH can indicate issues such as testicular failure or damage, which can lead to infertility.
Low Levels Indicate
Pituitary or hypothalamic disorders causing secondary hypogonadism.
Low levels of FSH can suggest several health concerns, particularly related to the pituitary gland or hypothalamus. These low levels may indicate secondary hypogonadism, where the pituitary gland does not produce enough FSH and luteinizing hormone (LH) to stimulate the gonads effectively. This condition can lead to delayed puberty in adolescents or low levels of sex hormones in adults, affecting reproductive health.
Why It's Tested
To evaluate fertility, menstrual irregularities, and gonadal function.
The FSH test is commonly utilized in clinical settings to assess various reproductive health issues. It is particularly useful in evaluating fertility problems in both men and women. In women, it helps to identify causes of menstrual irregularities, such as amenorrhea or oligomenorrhea. In men, it can help diagnose conditions related to low sperm production or other testicular issues. Thus, measuring FSH is an integral part of a comprehensive evaluation of reproductive health.
Associated Symptoms (if abnormal)
High: Menstrual irregularities, infertility.
Low: Delayed puberty, low sex hormone symptoms.
Abnormal FSH levels can lead to a range of symptoms depending on whether the levels are high or low. High levels of FSH in women may result in menstrual irregularities, such as heavy or missed periods, and can contribute to infertility issues. In men, elevated FSH levels can indicate problems with sperm production, leading to difficulties in fathering children. Conversely, low FSH levels may manifest in women as delayed puberty, absent menstrual cycles, or symptoms associated with low estrogen levels. In men, low FSH can lead to symptoms of low testosterone, such as reduced libido, erectile dysfunction, and decreased muscle mass.
What To Do If Abnormal
Check LH, estradiol/testosterone; further imaging and endocrine consult may be needed.
If FSH levels are found to be abnormal, it is essential to conduct further evaluations to understand the underlying cause. This may include measuring other hormones such as luteinizing hormone (LH), estradiol, and testosterone levels to gain a comprehensive picture of hormonal health. In some cases, imaging studies such as MRI or CT scans may be necessary to assess the pituitary gland or ovaries/testes. Consulting with an endocrinologist may also be recommended for specialized care and management of any identified hormonal disorders.
Common Conditions Related
Menopause, hypogonadism, pituitary disorders.
Several medical conditions are commonly associated with abnormal FSH levels. In women, menopause is a significant condition marked by elevated FSH levels due to decreased ovarian function. In both men and women, hypogonadism, which refers to insufficient hormone production by the gonads, can lead to low FSH levels. Additionally, various pituitary disorders, such as tumors or dysfunctions, can disrupt the normal production of FSH and other hormones, resulting in a cascade of reproductive health issues.
Nutrition or Lifestyle Connection
Healthy diet, maintaining body weight, avoiding excessive exercise helps hormonal balance.
Nutrition and lifestyle choices play a critical role in maintaining hormonal balance, including FSH levels. A healthy, balanced diet rich in essential nutrients can support overall endocrine function. Maintaining a healthy body weight is also crucial, as both obesity and being underweight can negatively impact hormone levels. Furthermore, engaging in excessive exercise can lead to hormonal disruptions, particularly in women, where it may cause amenorrhea or low FSH levels. Therefore, adopting a balanced lifestyle that includes regular physical activity, stress management, and a nutritious diet can help promote optimal reproductive health and hormonal balance.
References (APA Format)
Melmed, S. et al. (2016). Williams Textbook of Endocrinology (13th ed.). Elsevier.
MedlinePlus. (2023). Follicle Stimulating Hormone (FSH).
