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Thyroid Dysfunction and Diagnostic Challenges

There are cases where patients experiencing symptoms potentially related to thyroid dysfunction undergo standard testing for TSH hormone levels, and the results fall within the normal range. This often concludes the examination.

It is possible that, for this reason, many individuals in the Canadian province of BC remain undiagnosed for many years. They exhibit symptoms of thyroid dysfunction, yet specialists assure them that everything is fine, relying on the fact that thyroid-stimulating hormone (TSH) levels are within the normal range.

However, it is crucial to understand that TSH is not a thyroid hormone itself. Free thyroxine (thyroid hormone) may be low even with a normal TSH level.

How can residents of BC check their thyroid hormone levels? They can do so with a naturopathic doctor within the province or travel to another province and undergo testing with a doctor from a different jurisdiction where thyroid function analysis is not solely based on TSH.

What are the reasons for this phenomenon, and what are the consequences for patients? Let’s delve into this complex situation to understand what steps can be taken to refine the diagnosis and aid patients facing this issue.

Symptoms of Thyroid Problems

First and foremost, let’s review the symptoms that may indicate a thyroid problem. Insufficient or excessive thyroid hormone levels (hypothyroidism and hyperthyroidism) can cause various symptoms.

Hypothyroidism Symptoms (Hormone Deficiency):

  • Fatigue and weakness.
  • Decreased energy and endurance.
  • Memory and concentration problems.
  • Reduced body temperature.
  • Dry and flaky skin.
  • Body hair loss, not just on the head.
  • Weight gain despite a normal appetite.
  • Slow heart rate.
  • Digestive problems and constipation.
  • Depression and mood changes.
  • Fertility issues.

Hyperthyroidism Symptoms (Hormone Excess):

  • Nervousness, anxiety, irritability.
  • Increased heart rate (tachycardia).
  • Weight loss with a normal or increased appetite.
  • Increased sweating and heat sensitivity.
  • Tremors in hands and body.
  • Restlessness and sleep difficulties.
  • Menstrual cycle irregularities in women.
  • Eye changes, such as bulging eyes (exophthalmos).
  • Increased urination.
  • Skin changes, such as redness or itching.
  • Fertility issues.

These symptoms may vary based on the degree and duration of hormone imbalance and individual characteristics. Note that not all symptoms must be present; for example, with low thyroid hormone levels, the pulse may be normal, not slowed. This is because factors other than the thyroid hormone influence heart function.

Important Facts about the Thyroid Gland and Its Role in the Body

The thyroid gland is an organ located in the front part of the neck, and its functions are crucial for overall health. It produces hormones that influence nearly all cells and tissues in our body.

Let’s delve into the functions of the thyroid gland; this will help explain many symptoms related to thyroid issues:

  • Hormone Synthesis: The thyroid gland produces and releases two primary hormones – thyroxine (T4) and triiodothyronine (T3). These hormones regulate metabolism and affect virtually all processes in the body.
  • Metabolism Regulation: Thyroid hormones control the rate at which the body burns calories for energy production. They influence numerous processes, including digestion, thermoregulation, and the speed at which cells divide.
  • Growth and Development: Thyroid hormones play a crucial role in the growth and development of children and adolescents. Insufficient thyroid hormones in childhood can lead to slowed physical and mental development.
  • Cardiovascular System Regulation: Thyroid hormones affect the frequency and force of heart contractions. Thyroid underactivity can result in a slowed pulse and low blood pressure.
  • Mental State Regulation: Thyroid hormones influence mental state and emotions. Overactivity (hyperthyroidism) can cause nervousness and restlessness, while underactivity (hypothyroidism) may lead to depression and cognitive slowness.
  • Reproductive System Regulation: Thyroid hormones impact the reproductive system. Overactivity or underactivity of the thyroid gland can result in menstrual cycle irregularities and infertility in both women and men.
  • Energy and Heat Regulation: Thyroid hormones contribute to maintaining body temperature and regulating thermogenesis (heat production).
  • Digestive Control: The thyroid gland influences digestive processes by regulating the metabolism rate. Increased metabolism, caused by thyroid overactivity (hyperthyroidism), can lead to enhanced digestion, loose stools, and frequent hunger. In contrast, underactivity (hypothyroidism) can slow digestive processes, cause constipation, and result in a loss of appetite.
  • Fat Metabolism Regulation: Thyroid hormones affect fat metabolism, including distribution and utilization in the body.
  • Hair and Nail Growth Regulation: The thyroid gland influences hair and nail growth and their overall condition.

Description of Important Thyroid Hormone Functions

Now, let’s delve into the hormones associated with the thyroid gland.

TSH (Thyroid-Stimulating Hormone):

  • Half-life: Approximately 4-6 weeks.
  • TSH is produced by the pituitary gland, located in the brain. TSH acts as a regulator of thyroid gland function, helping maintain normal thyroid hormone levels.

T4 (Thyroxine):

  • Half-life: Approximately 7 days.
  • T4 is the main hormone produced by the thyroid gland and is an inactive form. Half of T4 converts to the active T3 in 7 days.

T3 (Triiodothyronine):

  • Half-life: About 1-2 days.
  • T3 is the active form of the thyroid hormone. It impacts cells, increasing metabolic rate and aiding energy production.

FT4 (Free Thyroxine) and FT3 (Free Triiodothyronine):

  • FT4 and FT3 are free, active forms of their respective hormones. They are more mobile and easily interact with cells, providing energy and regulating metabolism. Measuring free forms provides information about thyroid function.
  • Elevated FT4 levels may indicate hyperthyroidism, where the thyroid gland overproduces hormones. Reduced FT4 levels may suggest hypothyroidism, where the thyroid gland doesn’t produce enough hormones.
  • FT3 regulates metabolism, energy exchange, and essential physiological processes. Assessing FT3 levels helps evaluate thyroid gland activity.

Thyroid Hormone Ratios:

  • The T4 to T3 ratio in the blood is closer to 20:1.
  • The ratio of Free T4 to Free T3 in the blood is approximately 4:1 or 3:1. This means that the level of Free T3 in the blood is about 3-4 times lower than the level of Free T4. These ratios may slightly vary depending on the laboratory and units of measurement used.

Features of Thyroid Test Result Interpretation

Here are the key points to consider when interpreting thyroid test results. Here’s a more detailed explanation:

  • TSH (Thyroid-Stimulating Hormone): The TSH level changes relatively slowly. Typically, after a change in thyroid function, TSH levels may stabilize over 4-6 weeks. This is because TSH responds to the levels of T4 and T3 hormones, which, in turn, have different half-lives.
  • T4 (Thyroxine): T4 is the primary hormone produced by the thyroid gland. It is an inactive form and serves as a storage form. T4 levels may change more quickly. The half-life of T4 is approximately 7 days, meaning that within this time, half of the T4 in the body will convert to the active T3. If T4 levels are low, it may lead to insufficient T3 formation, even if T3 levels remain within the normal range.
  • T3 (Triiodothyronine): This hormone is the active form and has a shorter half-life (1-2 days). This allows the body to quickly respond to changes in hormone levels. However, because T3 can be rapidly utilized by the body, a low T4 level may ultimately result in a low T3 level. Detecting this in tests is more challenging due to the shorter half-life.

Additionally, the influence of the menstrual cycle on hormone levels should be considered. Fluctuations in estrogen and progesterone during different phases of the cycle can impact thyroid function. Therefore, thyroid hormone test results may vary during different menstrual cycle periods, emphasizing the importance of considering this factor in result interpretation and developing individualized treatment plans.

Factors Affecting Thyroid Function

This is a common question: What’s wrong? Why did my thyroid stop working properly? Is it possible to restore its function? Yes, there is a chance to restore thyroid function when the underlying issue causing the disruption is resolved. Here’s a list of problems:

  • Autoimmune Disorders: For example, autoimmune thyroiditis (Hashimoto’s) and Graves’ disease, where the immune system attacks the thyroid gland’s own cells.
  • Nutrient Deficiency: Below, I’ll show you how much thyroid function depends on nutrient intake and, consequently, on the functioning of the intestines.
  • Stress: Prolonged stress can affect thyroid function.
  • Hormonal Changes: For example, pregnancy and menopause can impact thyroid function.
  • Issues with the Hypothalamus and Pituitary Gland: For instance, hypofunction of the pituitary gland can lead to reduced production of thyroid hormones.
  • Medications: Some medications, such as amiodarone, lithium, propylthiouracil, and others, can affect the thyroid gland.
  • Dietary Factors: High histamine levels, certain foods (e.g., soy products), and allergies to specific foods can influence thyroid function.
  • Mycotoxins: Toxins produced by mold can affect the thyroid gland.
  • Infectious Issues: Infections can influence thyroid function. Infections can cause inflammation, which, in turn, can affect thyroid function. Inflammation can affect the tissues involved in the synthesis and regulation of thyroid hormones, leading to temporary changes in hormone levels.
  • Genetic Factors: Heredity can play a role in predisposition to thyroid diseases.
  • Environmental Factors: Exposure to toxins can influence thyroid function. The most well-known is the impact of radiation exposure.

Nutrients and the Thyroid Gland

Nutrients important for the functioning of the thyroid gland:

  • Iodine: Essential for the synthesis of thyroid hormones.
  • Selenium: Involved in the conversion of thyroxine (T4) to triiodothyronine (T3).
  • Zinc: Plays a role in regulating thyroid function.
  • Copper: Participates in the formation of tyrosine, a precursor to thyroxine.
  • Iron: Necessary for the synthesis of thyroid hormones.
  • Vitamin D: Influences thyroid hormone receptors.
  • Vitamin A: Facilitates the synthesis of thyroid hormones.
  • Protein: Important for the overall health of tissues, including the thyroid gland.

Nutrients required for the conversion of T4 to T3:

  • Selenium: Activates enzymes involved in conversion.
  • Zinc: Essential for proper conversion of thyroxine to triiodothyronine.
  • Copper: Participates in conversion processes.
  • Iron: Vital for the functioning of enzymes involved in conversion.
  • Vitamin A: Aids in the conversion of thyroxine to triiodothyronine.
  • Vitamin D: Influences the activation of thyroid receptors.
  • Vitamin B12: Important for overall health and maintaining normal energy levels.
  • Folate (B9): Participates in the metabolism of thyroid hormones.
  • Slow Carbohydrates: Maintain a stable glucose level, crucial for thyroid function.
  • Omega-3 Fatty Acids: Affect tissue sensitivity to thyroid hormones.

Isolated Low FT4 with Normal TSH

Certainly, there are numerous possible issues related to thyroid function, but I want to focus on this one specifically because it’s a common scenario in my practice. More precisely, the most frequent issue statistically is autoimmune thyroid disease, but it’s usually diagnosed before it reaches me. I’m referring to the problem not yet identified before reaching me. Let’s delve into the reasons for isolated low free thyroxine (FT4) levels with a normal thyroid-stimulating hormone (TSH):

Early Stage Hypothyroidism:

  • Description: Hypothyroidism is a condition where the thyroid gland doesn’t produce enough thyroid hormones. In the early stages of this condition, TSH levels may remain within the normal range because the body compensates for the hormone deficiency by increasing TSH.
  • Mechanism: In the initial phase of hypothyroidism, TSH levels may stay within the normal range, but FT4 levels may decrease due to a lack of the active hormone in the bloodstream.

Conversion Issues from T4 to T3:

  • Description: T4 is an inactive form of the hormone, and most of its activity occurs after conversion to the active form, T3. Issues with this process can lead to low T3 levels despite maintaining a normal TSH level.
  • Mechanism: Insufficient active hormone (T3) can be one reason for low FT4 levels with a normal TSH. This can occur due to problems with the conversion of thyroxine (T4) to its more active form, triiodothyronine (T3). If the conversion process is slowed or impaired, the active T3 may be insufficient, affecting the overall balance of thyroid hormones.

These are just a few examples of possible problems; there are many more. That’s why it’s crucial to pay attention to unusual symptoms and seek a specialist who can investigate the potential causes of these symptoms and prescribe timely treatment.


Comprehending the intricacies of thyroid function and its influencing factors is pivotal for maintaining overall health. The thyroid gland, situated in the neck, plays a key role in regulating various bodily processes through the production of hormones like thyroxine (T4) and triiodothyronine (T3). These hormones impact metabolism, growth, development, cardiovascular function, reproductive systems, and even mental well-being.

The interpretation of thyroid test results requires a nuanced approach, considering the interplay of hormones such as thyroid-stimulating hormone (TSH), T4, and T3. Thyroid disorders, whether in the early stages of hypothyroidism or issues with the conversion of T4 to T3, can present challenges in diagnosis and treatment. I emphasize once again: that a Naturopathic Doctor can assess your thyroid function and help improve your health even when TSH is still within the normal range.