Relationship Between TSH Levels and the Menstrual Cycle

Have you ever noticed your period acting strangely? You're not alone. Many women experience irregular cycles, heavy bleeding, or even skipped periods.

For some, thyroid-stimulating hormone (TSH) might be the culprit. [1] The pituitary gland located at the base of the brain produces it. This structure acts like a conductor, telling the thyroid how much triiodothyronine (T3) and thyroxine (T4) to produce.

Let's explore the surprising connection between TSH levels—the most sensitive marker for thyroid function—and your period. We'll see how hypo– and hyperthyroidism can disrupt your menstrual cycle and what you can do to get things back on track.

Overview of the menstrual cycle

The menstrual cycle is a complex hormonal process that typically lasts around 28 days, though it can vary between 21 and 35 for most women. [3]

The ovaries and uterus undergo natural changes to prepare for pregnancy. Estrogen, progesterone, luteinizing (LH), and follicle-stimulating hormone (FSH) regulate the process.

The cycle has four main phases: menstrual, follicular, ovulation, and luteal. Each phase has specific hormonal changes and functions.

1. Menstrual phase

In the absence of pregnancy, the dominant follicle slows the production of estrogen and progesterone. The thickened uterine lining no longer receives the hormonal signals to stay put. It breaks, and the body sheds it over time.

» Otpimize training around your menstrual cycle

2. Follicular phase

The follicular phase kicks off with the hypothalamus. This region in your brain sends a signal to the pituitary gland, prompting it to release the follicle-stimulating hormone (FSH).

FSH stimulates the ovaries to develop multiple tiny sacs called follicles. They have around five to 20 immature eggs, which begin growing at the start of this phase. [4]

One eventually becomes dominant and starts producing increasing amounts of estrogen. [5] The hormone stimulates the thickening of the uterus's lining.



3. Ovulation phase

In response to the surge in estrogen, the pituitary gland releases luteinizing hormone (LH). The LH surge triggers ovulation, which triggers the release of a mature egg from the dominant follicle.

4. Luteal phase

The luteal phase is all about preparing for a potential pregnancy. The leftover empty follicle from ovulation transforms into a temporary structure called the corpus luteum.

It starts pumping out progesterone alongside some estrogen. The former plays a vital role in thickening and nourishing the uterine lining to create a welcoming environment for a fertilized egg. But, the corpus luteum has a short lifespan, the egg doesn't implant, it shrinks and disappears. [6,7]

What does science say about the luteal phase?

Interestingly, there's a link between elevated hs-CRP and symptoms of PMS, which typically occur in the luteal phase. A prospective cohort study examined how this inflammation marker fluctuates throughout the menstrual cycle. [8] Their findings revealed significant changes in its levels:

• Highest peak occurred during menstruation.
• Levels steadily decreased throughout the follicular phase.
• The lowest point was reached around ovulation.
• Levels then increased back to baseline during the luteal phase.

Since hs-CRP fluctuates throughout your cycle, the timing of blood tests can significantly impact the results. When cortisol levels are chronically elevated due to stress, it can also trigger low-grade inflammation in the body, which can lead to an increase in hs-CRP.

Focusing on anti-inflammatory dietary and lifestyle changes might help alleviate symptoms due to the potential link between inflammation and PMS.



How TSH affects the menstrual cycle

TSH also plays a role in regulating the menstrual cycle, although indirectly. The pituitary gland produces it and stimulates the thyroid to its hormones, which regulate many bodily functions, including metabolism, heart rate, and body temperature.

An increase in hormone production can appear as hyperthyroidism. Graves' disease is the most common cause of this condition. It prompts your immune system to attack your thyroid gland with antibodies. [9]

On the other hand, a lower fabrication rate causes hypothyroidism. Hashimoto's thyroiditis, an autoimmune condition, is the leading cause of it in the US. [10] The disorder gradually leads the white blood cells towards the destruction of the thyroid tissue.

It can lead to various menstrual irregularities, including.

• Irregular periods: This can manifest as cycles that are shorter or longer than your usual pattern, or even skipped periods.
• Cycle irregularities: Changes in bleeding patterns, such as heavier or lighter periods than usual, can occur. [10]
• Ovulation issues: Hypothyroidism can sometimes affect ovulation, the release of an egg from the ovary, which can further impact menstrual regularity. [11]

Treating menstrual irregularities

If you have struggled with menstrual irregularities for a while, it's a good idea to visit a doctor. Testing levels during menstruation can illuminate whether or not these are related to thyroid function. This proactive approach can speed up treatment and get you back on track.

There are a variety of interventions for thyroid disorders, depending on the kind. These may include medication management to replace hormones or moderate them, surgery, or radiation on the medical side of things.



Lifestyle factors and thyroid health

Living a healthy lifestyle can significantly improve your thyroid function and menstrual regularity. [13] Here's a breakdown of practical tips you can incorporate into your daily routine:

Embrace a thyroid-healthy diet

Your thyroid gland uses certain nutrients to produce hormones that regulate metabolism, and deficiencies in iodine, selenium, and zinc can impair its function. [14] A balanced diet rich in fruits, vegetables, whole grains, and legumes will help ensure you get enough of them.

Cruciferous vegetables like cabbage, cauliflower, and kale contain goitrogens, which can interfere with iodine uptake by the thyroid. [15] They can even reduce the effectiveness of TSH, indirectly causing an irregular menstrual cycle. But, the amount you'd need to eat for this effect is relatively high.

Exercise

A study from Duke University investigated the long-term effects of daily physical activity on metabolism and immunity using an extensive survey with activity tracking. [16]

They found that active people had lower levels of T4 hormone and a healthier balance between it and TSH. These findings suggest that daily physical activity can contribute to a healthy thyroid system, but more research is necessary to confirm the effects.

Manage stress

Yoga may be an effective complementary stress management therapy for women with hypothyroidism. [17] A systematic review of studies found that it may improve various health measures, but more high-quality studies are needed to confirm this.

Get your period back on track

There's an undeniable connection between TSH levels and menstrual cycle regularity. Medication or lifestyle changes may help to manage this to result in improved health outcomes, but you should always consult with a healthcare professional first.

Additionally, the Ultimate plan from InsideTracker measures TSH, progesterone, and estradiol, among other biomarkers. You'll then get science-backed recommendations to optimize your menstrual cycle and health span—the number of years you can live feeling your best.

References:

[1] Y. Pirahanchi, F. Toro, and I. Jialal, “Physiology, thyroid stimulating hormone,” StatPearls - NCBI Bookshelf, May 01, 2023. Available: https://www.ncbi.nlm.nih.gov/books/NBK499850/

[2] M. B. Leko, I. Gunjača, N. Pleić, and T. Zemunik, “Environmental factors affecting Thyroid-Stimulating hormone and thyroid hormone levels,” International Journal of Molecular Sciences, vol. 22, no. 12, p. 6521, Jun. 2021, doi: 10.3390/ijms22126521. Available: https://pubmed.ncbi.nlm.nih.gov/34204586/

[3] D. K. Thiyagarajan, H. Basit, and R. Jeanmonod, “Physiology, menstrual cycle,” StatPearls - NCBI Bookshelf, Oct. 24, 2022. Available: https://www.ncbi.nlm.nih.gov/books/NBK500020/

[4] B. G. Reed and B. R. Carr, “The normal menstrual cycle and the control of ovulation,” Endotext - NCBI Bookshelf, Aug. 05, 2018. Available: https://www.ncbi.nlm.nih.gov/books/NBK279054/

[5] J. E. Holesh, A. N. Bass, and M. Lord, “Physiology, ovulation,” StatPearls - NCBI Bookshelf, May 01, 2023. Available: https://www.ncbi.nlm.nih.gov/books/NBK441996/

[6] M. Zerani, A. Polisca, C. Boiti, and M. Maranesi, “Current knowledge on the multifactorial regulation of Corpora Lutea Lifespan: the Rabbit Model,” Animals, vol. 11, no. 2, p. 296, Jan. 2021, doi: 10.3390/ani11020296. Available: https://pubmed.ncbi.nlm.nih.gov/33503812/

[7] R. Oliver and L. S. Pillarisetty, “Anatomy, abdomen and pelvis, ovary corpus luteum,” StatPearls - NCBI Bookshelf, Jan. 01, 2023. Available: https://www.ncbi.nlm.nih.gov/books/NBK539704/

[8] A. J. Gaskins et al., “Endogenous reproductive hormones and C-reactive protein across the menstrual cycle: the BioCycle Study,” American Journal of Epidemiology, vol. 175, no. 5, pp. 423–431, Feb. 2012, doi: 10.1093/aje/kwr343. Available: https://pubmed.ncbi.nlm.nih.gov/22306563/

[9] “Graves’ disease,” National Institute of Diabetes and Digestive and Kidney Diseases, Nov. 16, 2022. Available: https://www.niddk.nih.gov/health-information/endocrine-diseases/graves-disease

[10] D. L. Mincer and I. Jialal, “Hashimoto thyroiditis,” StatPearls - NCBI Bookshelf, Jul. 29, 2023. Available: https://www.ncbi.nlm.nih.gov/books/NBK459262/

[11] S. Saran et al., “Effect of hypothyroidism on female reproductive hormones,” Indian Journal of Endocrinology and Metabolism, vol. 20, no. 1, p. 108, Jan. 2016, doi: 10.4103/2230-8210.172245. Available: https://pubmed.ncbi.nlm.nih.gov/26904478/

[12] A. C. Bianco et al., “Levothyroxine Treatment Adequacy and Formulation Changes in Patients with Hypothyroidism: A Retrospective Study of Real-World Data from the United States,” Thyroid, vol. 33, no. 8, pp. 940–949, Aug. 2023, doi: 10.1089/thy.2022.0382. Available: https://pubmed.ncbi.nlm.nih.gov/37335236/

[13] S. Dhar, K. K. Mondal, and P. Bhattacharjee, “Influence of lifestyle factors with the outcome of menstrual disorders among adolescents and young women in West Bengal, India,” Scientific Reports, vol. 13, no. 1, Aug. 2023, doi: 10.1038/s41598-023-35858-2. Available: https://pubmed.ncbi.nlm.nih.gov/37528155/

[14] S. Y. Hess, “The impact of common micronutrient deficiencies on iodine and thyroid metabolism: the evidence from human studies,” BaillièRe’s Best Practice and Research in Clinical Endocrinology and Metabolism/Baillière’s Best Practice & Research. Clinical Endocrinology & Metabolism, vol. 24, no. 1, pp. 117–132, Feb. 2010, doi: 10.1016/j.beem.2009.08.012. Available: https://pubmed.ncbi.nlm.nih.gov/20172476/

[15] A. Babiker, A. Alawi, M. A. Atawi, and I. A. Alwan, “The role of micronutrients in thyroid dysfunction,” Sudanese Journal of Paediatrics, pp. 13–19, Jan. 2020, doi: 10.24911/sjp.106-1587138942. Available: https://pubmed.ncbi.nlm.nih.gov/32528196/

[16] C. L. Klasson, S. Sadhir, and H. Pontzer, “Daily physical activity is negatively associated with thyroid hormone levels, inflammation, and immune system markers among men and women in the NHANES dataset,” PloS One, vol. 17, no. 7, p. e0270221, Jul. 2022, doi: 10.1371/journal.pone.0270221. Available: https://pubmed.ncbi.nlm.nih.gov/35793317/

[17] A. Baishya and K. Metri, “Effects of yoga on hypothyroidism: A systematic review,” Journal of Ayurveda and Integrative Medicine, vol. 15, no. 2, p. 100891, Mar. 2024, doi: 10.1016/j.jaim.2024.100891. Available: https://pubmed.ncbi.nlm.nih.gov/38507967/