Hypothyroidism: Recognizing Symptoms in Women

Overview of the most common symptoms in women

Not all symptoms necessarily occur simultaneously, and their intensity often varies. A combination of general and female-specific signs is typical.

General Symptoms

• Persistent tiredness and exhaustion that remains even after sleep
• Weight gain without changes in diet
• Sensitivity to cold and constant feeling of being cold
• Constipation and sluggish bowels
• Dry skin, brittle nails, and hair loss
• Concentration problems and low mood, even leading to depressive moods

Female-Specific Symptoms

• Irregular cycles or missed periods
• Heavier or prolonged menstrual bleeding
• Unfulfilled desire to have children and fertility problems
• Decreased libido

Important:Many of these symptoms are non-specific and can have other causes, ranging from iron deficiency to menopause to stress. Precisely for this reason, hypothyroidism can never be diagnosed solely based on symptoms, but only through a blood test.

Causes: Where an underactive thyroid comes from

By far the most common cause of acquired hypothyroidism in regions with adequate iodine supply is the autoimmune disease Hashimoto's thyroiditis. In this condition, the immune system attacks its own thyroid gland, damaging it over years. According to Huwiler and colleagues (2024), Hashimoto's is the leading cause of hypothyroidism worldwide, and women are four to ten times more likely to be affected than men.

Other possible triggers include severe iodine deficiency, consequences of thyroid surgery or radioiodine therapy, certain medications, and temporary postpartum thyroiditis after childbirth. A special form is latent or subclinical hypothyroidism: here, only TSH is elevated, while thyroid hormones themselves are still within the normal range. It is often asymptomatic but can progress to overt hypothyroidism.

Diagnosis: Which values really count

Diagnosis relies on a simple blood test. The most important initial value is TSH. If it is elevated, free T4 (fT4) is then determined to differentiate between latent and overt hypothyroidism. To clarify the cause, thyroid antibodies (especially TPO antibodies) are also measured, which indicate Hashimoto's.

A detail often overlooked: The German S2k guideline of the DEGAM for elevated TSH values (AWMF register 053-046, 2023) defines the TSH threshold as age-dependent. For adults up to 70 years, a value above 4.0 mU/l is considered elevated, between 70 and 80 years above 5.0 mU/l, and from 80 years above 6.0 mU/l. This accounts for the natural increase in TSH with age and prevents overdiagnosis.

In cases of overt hypothyroidism, treatment with the thyroid hormone levothyroxine (LT4) is indicated according to the guideline. For latent hypothyroidism, the decision is made individually. This decision is always made by a doctor, not by a self-test.

Nutrition and Micronutrients: What the evidence shows

No pill for hypothyroidism can be replaced by diet. However, individual micronutrients are building blocks of thyroid function, and in case of a deficiency, targeted intake can be beneficial.

Selenium. Selenium is a component of enzymes that metabolize thyroid hormones. A meta-analysis of randomized studies by Huwiler and colleagues (2024) showed that selenium supplementation in Hashimoto's can lower TPO antibodies and TSH. However, a clear effect on the free thyroid hormones fT3 and fT4 could not be proven. Thus, selenium can influence the autoimmune process, but it does not replace hormone therapy.

Iodine. Iodine is the basic building block of thyroid hormones. Both a deficiency and an excess can disrupt the thyroid gland; especially with Hashimoto's, high-dose iodine is problematic. Therefore, a general iodine supplementation on your own is not recommended.

Vitamin D and Iron. Vitamin D deficiency is common in thyroid diseases, but clear evidence that supplementation improves thyroid function is still lacking. For women, it is also worth looking at iron status: increased bleeding due to hypothyroidism can worsen iron deficiency, which in turn fuels fatigue and hair loss.

What you can do yourself

• If you have persistent symptoms, have your TSH determined, supplemented with fT4 and TPO antibodies if abnormalities are found.
• Take prescribed levothyroxine consistently and always at the same time, on an empty stomach, away from coffee and calcium.
• If you switch manufacturers of the medication, ensure a new value check.
• If you experience increased bleeding, have your iron and ferritin levels checked.
• Focus on a balanced diet with sufficient selenium (e.g., from Brazil nuts) instead of high-dose self-experimentation.

When you should seek medical advice

Seek medical advice if several of the symptoms mentioned persist for weeks, if your cycle changes significantly, if you have an unfulfilled desire to have children, or if thyroid diseases are known in your family. During pregnancy, clarification is particularly important, as an untreated underactive thyroid poses risks for both mother and child.

Conclusion

Hypothyroidism in women often hides behind complaints that are attributed to everyday life, stress, or age: fatigue, weight gain, feeling cold, and a disrupted cycle. Because the symptoms are non-specific, the path to clarity always leads through a blood test, especially TSH, evaluated according to age-dependent reference ranges.

The basis of treatment for manifest hypothyroidism is thyroid hormone, not supplements. Micronutrients like selenium can support the process but do not replace medical therapy. If you recognize yourself in the symptoms, the most important step is to have your levels checked and interpreted together with a doctor.