PRO Pregnancy & Motherhood 7 min read

Thyroid Hormone Insufficiency

Julia Wójcik ✓

Diets Premium Expert • 23.03.2026

✓

Scientifically reviewed by a clinical dietitian: This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.

Diets Premium Expert Julia Wójcik

min read 7 min

Scientifically reviewed by a clinical dietitian 23.03.2026

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Key Takeaways

The most prevalent thyroid disorder, this primarily affects older individuals. However, it poses the most significant risk for pregnant women as it can result in various complications. Discover how to suspect and recognize an insufficiency of thyroid hormones.

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What is the phenomenon of Hypothyroidism

Hypothyroidism is a pathological condition caused by insufficient levels of thyroid hormones. The thyroid gland mainly produces thyroxine (T4) and triiodothyronine (T3), with T3 being the more active form and primarily produced from T4. Hypothyroidism can be primary or secondary. Primary hypothyroidism is due to improper functioning of the thyroid gland itself, while secondary hypothyroidism is caused by a deficiency of TSH (thyroid-stimulating hormone), a hormone produced by the pituitary gland that reaches the thyroid receptors and stimulates it to work. The most common cause of primary hypothyroidism is Hashimoto's disease, an autoimmune disorder characterized by the production of antibodies against thyreoperoxidase and thyreoglobulin. To determine whether hypothyroidism is caused by Hashimoto's disease, the level of anti-TPO antibodies is measured. Hypothyroidism can also be caused by medication-induced damage, such as during treatment with radioactive iodine or amiodarone.

What symptoms suggest hypothyroidism?

The main symptoms of hypothyroidism include: - a reduction in the rate of basic metabolism, leading to weight gain, - a decrease in body temperature, - impairment of concentration and memory, - a weakening of muscle strength, - difficulty breathing due to weakened respiratory muscles, - an increase in LDL cholesterol, - inducing anemia, - constipation, - dry and cold skin, - hoarseness, - hair loss, - yellow-orange discoloration of the skin due to disorders of the conversion of carotene to A, - milk secretion in women, breast enlargement in men. The aforementioned symptoms are non-specific and cannot be diagnosed solely based on the symptoms. Further laboratory tests are required.

Establishing the diagnosis

To establish the diagnosis of thyroid insufficiency, the examination of TSH, FT4 (free thyroxine) and FT3 (free triiodothyronine) levels is essential. In primary deficiency, an elevated level of TSH is typically observed, while in secondary deficiency, the level is lowered. The FT4 level is lowered, while FT3 is usually normal. Additionally, a test for anti-TPO (antihyperthyroid antibodies) can be performed, which allows for the determination of whether Hashimoto's disease is the cause of the symptoms. It is also possible to conduct additional tests such as the measurement of triglyceride and LDL cholesterol levels and the performance of a blood count to assess the presence of anemia. Examinations for thyroid insufficiency should be carried out prior to a planned pregnancy if instances of thyroid dysfunction have occurred in the woman's family or if the patient suffers from autoimmune diseases in which the body produces antibodies against its own tissues (e.g. type 1 diabetes). The TSH level should also be measured between the 4th and 8th week of pregnancy. It is always crucial to remember that the diagnosis is made by a doctor.

Treatment of thyroid hormone deficiency

Treatment of evident thyroid hormone deficiency is based in most cases on the lifelong use of synthetic levothyroxine. It is typically taken in the morning on an empty stomach, at least 30 minutes before the first meal. It is essential to remember that the first meal after taking the medication should not be rich in fiber or calcium, as a high content of these components can hinder absorption. The effectiveness of treatment for primary deficiency is evaluated based on the TSH concentration in the blood serum from 4 to 6 weeks after starting to use a specific dose of thyroxine.

What the menu should look like in hypothyroidism

A menu for hypothyroidism should be appropriately balanced in terms of calorie intake, taking into account the slowed metabolism in this condition. It should be created according to the rules of rational nutrition, with emphasis on providing adequate doses of iron, vitamin B12, zinc, and selenium. Absorption of iron and vitamin B12 can be impaired, requiring increased intake. Protein, as a source of tyrosine, is necessary for the synthesis of thyroxine and should be included in daily nutrition. Carbohydrates with a low glycemic index should be the main source of energy, and unsaturated fatty acids, present in plant oils, avocado, and kernels, improve the conversion of T4 to active T3. An elimination diet is not justified in the treatment of hypothyroidism. Below is an example menu.

Physical activity and hypothyroidism

Regular physical activity could potentially enhance thyroid function. This is supported by a study conducted in India a few years ago involving 20 patients undergoing treatment for hypothyroidism. Of these, 10 individuals were physically active (engaging in at least an hour of exercise daily). After a period of three months, the physically active group showed a significant decrease in TSH levels and an increase in T3 and T4 secretions, indicating improved thyroid function without the need to increase medication dosage. However, no such changes were observed in the control group. It is important to note that these exercises were of moderate intensity (at 70% of the maximum heart rate). While not all studies confirm the impact of physical exercise on thyroid hormone levels, daily activity of moderate intensity is recommended for everyone due to its numerous health benefits, and those with hypothyroidism are no exception.