woman tired from misdiagnosed thyroid dysfunction

Under Active Thyroid Symptoms With Normal TSH

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Dr. Kimberly Boileau

Weight Loss
Hormonal Health

I find insightful solutions to hormone burnout, helping you restore energy, gain control over your weight and harness the hormonal superpowers you are made to enjoy.

Hi, I'm Dr. Kim

Someone enters my office every day with under active thyroid symptoms with normal TSH levels. When it comes to hypothyroidism, reliance on standard thyroid function tests may lead to misdiagnosis and inadequate treatment. Many individuals experiencing classic symptoms of an under active thyroid find themselves dismissed due to normal blood test results. This blog post explores the limitations of conventional thyroid panels and sheds light on five often-overlooked patterns of thyroid dysfunction.

The Limitations of Conventional Thyroid Panels:

When patients present with a range of hypothyroidism symptoms, conventional healthcare often resorts to standard thyroid panels, mainly measuring thyroid-stimulating hormone (TSH) and thyroxine (T4). However, this approach has its challenges:

  1. Incomplete Picture: TSH and T4 measurements alone may not provide a comprehensive understanding of thyroid function[^1^]. Additional indicators like free T4, free triiodothyronine (T3), and reverse triiodothyronine (rT3) are essential for a more thorough assessment.
  2. Variable Reference Ranges: Reference ranges for TSH and T4 vary across laboratories, making it challenging to establish a universal standard[^2^]. This discrepancy can confuse patients and hinder accurate diagnosis.
  3. Unwell Population Data: Conventional reference ranges are derived from data obtained from individuals undergoing lab tests, many of whom are already facing health challenges[^3^]. This may skew the perception of what constitutes a “normal” thyroid function.

The Five Patterns of Thyroid Dysfunction:

The complexity of thyroid physiology extends beyond what standard tests can reveal. This is what leaves many of my patients wondering why they have under active thyroid symptoms with normal TSH levels. Here are five patterns often missed by conventional panels:

  1. Hypothyroidism Resulting from Pituitary Dysfunction: Elevated cortisol levels, influenced by factors like stress and chronic inflammation, can exhaust the pituitary gland, impairing its ability to secrete TSH (1, 2, 8, 9, 10)
  2. Under-Conversion of T4 to T3: Inadequate conversion of thyroxine (T4) to triiodothyronine (T3) can result from factors like inflammation, cortisol imbalances, nutrient deficiencies, and disruptions in gut microorganisms (1, 2, 3, 4, 5, 6, 7)
  3. Elevated Thyroxine-Binding Globulin (TBG): imbalanced estrogen levels can increase TBG levels, limiting the availability of unbound thyroid hormone (14)
  4. Diminished Thyroxine-Binding Globulin (TBG) Levels: Reduced TBG levels elevate free thyroid hormone levels, leading to cellular resistance to thyroid hormones (13)
  5. Thyroid Resistance: A condition where the thyroid and pituitary glands function normally, but cellular receptors are less responsive to thyroid hormones

Addressing these patterns requires a nuanced approach tailored to each patient’s unique circumstances.

Comprehensive Diagnostic Strategies:

To overcome the limitations of standard thyroid tests, I consider a more comprehensive set of diagnostic tools:

  1. Expanded Thyroid Markers: A comprehensive panel including TSH, T3, T4, free T3, and free T4 offers a more detailed insight into thyroid function
  2. DUTCH Test: This diagnostic tool assesses the functioning of the hypothalamic-pituitary-adrenal (HPA) axis, providing valuable information on potential pituitary dysfunction, under-conversion of T4 to T3, or thyroid hormone resistance (8, 9, 10)
  3. Hormone Measurements: Assessing estrogen and testosterone levels can help identify the role of raised or decreased TBG levels in hypothyroidism (13, 14, 15, 16).
  4. Blood Sugar and Insulin Assessment: Evaluating fasting blood sugar and hemoglobin A1c helps identify blood sugar imbalances and insulin resistance, particularly relevant in cases of pituitary dysfunction
  5. Nutrient Status Evaluation: Assessing ferritin and serum selenium levels helps identify iron and selenium deficits contributing to thyroid dysfunction (11, 12).
  6. Gastrointestinal Health Evaluation: Utilizing tests like stool testing, hydrogen breath testing for SIBO, and a urine organic acids profile can uncover gastrointestinal infections and dysbiosis impacting thyroid health.

The intricacies of thyroid health extend far beyond what conventional tests can unveil. By recognizing the limitations of standard thyroid panels and employing comprehensive diagnostic strategies, healthcare practitioners can uncover nuanced patterns of thyroid dysfunction and tailor treatments to address the root causes, offering patients a more effective path to optimal thyroid health.


1: https://www.karger.com/Article/Pdf/97337

2: https://www.ncbi.nlm.nih.gov/pubmed/7921215

3: https://www.sciencedirect.com/science/article/pii/0024320589901793?via%3Dihub

4: https://www.sciencedirect.com/science/article/pii/S0303720717300758

5: https://www.ncbi.nlm.nih.gov/pubmed/25516464

6: http://www.jbc.org/content/275/49/38296

7: https://www.ncbi.nlm.nih.gov/pubmed/7593416

8: https://www.frontiersin.org/articles/10.3389/fendo.2018.00097/full

9: https://www.ncbi.nlm.nih.gov/pubmed/6783498

10: https://www.ncbi.nlm.nih.gov/pubmed/8597390

11: https://www.ncbi.nlm.nih.gov/pubmed/7435650

12: https://www.ncbi.nlm.nih.gov/pubmed/8427195

13: http://www.fertstert.org/article/S0015-0282%2816%2959363-7/abstract

14: https://www.hindawi.com/journals/jtr/2011/875125/

15: https://www.ncbi.nlm.nih.gov/pubmed/16409223

16: https://www.ncbi.nlm.nih.gov/pubmed/16793944

17: https://www.ncbi.nlm.nih.gov/pubmed/2574767

18: https://www.ncbi.nlm.nih.gov/pubmed/11010821

19: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559105/

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