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Writer's pictureTanya Kurzbock

Optimal versus Normal Thyroid Test Results Explained

Updated: May 22

Have you had your thyroid tested and it came back as "normal" even though you don't feel normal?


Is it conceivable that the optimal level varies from person to person?


Can standard testing miss early thyroid disease progression?


Could your genetic makeup influence your thyroid function?


This blog will discuss the difference between optimal and normal thyroid test results, and give you access to resources to reliably asses your own thyroid status at home.


How to read your thyroid test results.
How to read your thyroid test results.

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Hormones are complex. It is true that when someone has signs of hormonal imbalance, there are always several factors driving these symptoms, and a simple TSH screen test for thyroid function misses a huge percentage of people who are living with a sub-optimal thyroid.


First, let's break down the jargon:


What is suboptimal thyroid?

Suboptimal thyroid refers to a condition where thyroid hormone levels are not within the ideal or optimal range for maintaining overall health and well-being. This blog will share with you the optimal reference ranges that you should be aiming for to claim your best health.


What is TSH?

TSH stands for Thyroid Stimulating Hormone. It is a hormone produced by the pituitary gland, a small gland located at the base of the brain. TSH plays a crucial role in regulating the thyroid gland's production of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3). When thyroid hormone levels in the blood are low, the pituitary gland releases more TSH to stimulate the thyroid gland to produce more hormones. Conversely, when thyroid hormone levels are high, TSH production decreases to signal the thyroid gland to reduce hormone production. TSH levels are commonly measured through blood tests to assess thyroid function, with abnormal levels often indicating thyroid disorders such as hypothyroidism or hyperthyroidism.

Many people get confused looking at bloods - but basically, if TSH if high, your thyroid function is low, and vise versa.

Why do the normal thyroid reference range miss some thyroid disorders?

Normal thyroid reference ranges may miss some thyroid disorders because they are based on statistical population averages and do not account for individual variations in thyroid function. Additionally, these reference ranges are often broad and may not capture subtle deviations from optimal thyroid hormone levels that could indicate underlying thyroid dysfunction.


Another reason is that GPs and endocrinologists are in the business of treating disease states. Understanding that a thyroid disease can take many years to develop, as in the case of Hashimoto's disease, this is not addressed by medical care until the disease parameters are met. This is because prescribing medication will cause a dependence on the medication and in turn create a thyroid imbalance.


GPs are only licensed to prescribe drugs - they are not licensed or insured to use diet, herbs, or nutrients to address any developing thyroid conditions. Instead, it is a wait and see approach, waiting for the disease to finally become severe enough to warrant treatment.


Thyroid symptoms list

Most important of all are your symptoms - regardless of what your labs and test results show.


The Top 10 Thyroid Symptoms are:

  1. Fatigue: Persistent tiredness or exhaustion, even after getting enough rest, is a hallmark symptom of thyroid dysfunction, particularly hypothyroidism (underactive thyroid).

  2. Weight Changes: Unexplained weight gain or difficulty losing weight despite maintaining a healthy diet and exercise routine can be indicative of thyroid issues, especially hypothyroidism.

  3. Mood Changes: Thyroid imbalances can affect mood and mental well-being. Symptoms may include depression, irritability, anxiety, or mood swings.

  4. Changes in Hair and Skin: Dry, brittle hair that falls out easily, as well as dry, itchy skin, are common symptoms of thyroid disorders, particularly hypothyroidism. Conversely, excessive sweating and thinning hair may indicate hyperthyroidism (overactive thyroid).

  5. Temperature Sensitivity: Feeling unusually cold or having cold extremities, even in warm environments, is a common symptom of hypothyroidism. Conversely, excessive sweating and sensitivity to heat may occur with hyperthyroidism.

  6. Muscle Weakness and Joint Pain: Thyroid dysfunction, particularly hypothyroidism, can lead to muscle weakness, aches, and pains, as well as stiffness in the joints. These symptoms may interfere with daily activities and exercise.

  7. Irregular Menstrual Cycles: Thyroid imbalances can disrupt the menstrual cycle, leading to irregular periods, heavier or lighter bleeding than usual, or changes in menstrual flow. In some cases, thyroid dysfunction may also contribute to fertility issues.

  8. Digestive Issues: Some individuals with thyroid disorders, particularly hypothyroidism, may experience constipation, bloating, or other gastrointestinal disturbances. These symptoms can affect digestion and nutrient absorption.

  9. Cognitive Impairment: Thyroid dysfunction can impact cognitive function, leading to difficulties with memory, concentration, and mental clarity. Brain fog and forgetfulness are common complaints among individuals with thyroid disorders.

  10. Changes in Heart Rate and Blood Pressure: Thyroid hormones play a crucial role in regulating heart function. Hyperthyroidism can lead to an increased heart rate (tachycardia), palpitations, and high blood pressure, while hypothyroidism may cause a slower heart rate (bradycardia) and low blood pressure.


There are over 300 shared symptoms that occur when the thyroid is suboptimal!

If you would like to dive into this further, download the Thyroflex Form below and then email the result back to us after booking a Free Discovery Call.





Optimal vs Normal Thyroid Test Ranges Table

If you struggle with the listed symptoms then you should compare your actual lab tests to the “optimal ranges” provided below.

Test Name

Test abbreviation

Action In Body

Normal Reference Range

Optimal Reference Range

Thyroid-stimulating hormone

TSH

A pituitary gland hormone - it stimulates the thyroid hormone production.

0.450 – 4.500 IU/mL

0.5 – 1.5 IU/mL

Free T3, Triiodothyronine

FT3

Active thyroid hormone

 3.1 - 6.8 pmol/mL

 5.9 - 6.8 pmol/mL

Free T4, Thyroxine

FT4

Inactive thyroid hormone waiting to be activated.

12 - 22 pmol/mL

15.4 - 19.3 pmol/mL

Reverse T3, Reverse Triiodothyronine

RT3

Inactive thyroid hormone - T4 converted to an inactive form.

 170 - 450 pmol/mL

170 - 260 pmol/mL

Thyroglobulin Antibody

TgAB

Autoimmune marker

<115 IU/mL

<115 IU/mL

Thyroid Peroxidase Antibody

TPOab

Autoimmune marker

<34 IU/mL

<34 IU/mL

You will notice that the optimal range is a “tighter” version of the reference range. 


Note that each lab test has slightly different reference ranges so your test result may have slightly different numbers - but you can use the optimal ranges above as these are standard in a healthy body. 


If TSH is above 1.5 your thyroid is low - quote
If TSH is above 1.5 your thyroid is low

What does a full thyroid panel tell you?

By getting a broader picture of how the thyroid hormones are being produced, converting, and the drivers behind thyroid conditions, a full thyroid panel gives a more in-depth view of what could be driving your symptoms.


Many times TSH is in the normal range, yet very low free T3 (the active hormone) is seen. Medically this is called eurythyroid, or Low T3 Syndrome. This can be caused by many factors, such as nutrient deficiencies, enzyme dysfunction causing excess conversion of reverse T3, or cortisol (stress hormone) issues affecting the thyroid conversion.


Other thyroid-related tests

  • Ferritin:  Iron plays several essential roles in thyroid hormone synthesis, metabolism, and function, so checking ferritin (your iron stores) is essential in a full workup.

  • Vitamin D:  vitamin D is important for thyroid health due to its regulatory effects on gene expression, immune function, inflammation, calcium homeostasis, and parathyroid hormone regulation. Issues that can affect your ability to synthesise vitamin D from the sun include; obesity, liver conditions, and impaired digestion.

  • Cholesterol - Total, LDL, and LDL: One of the first metabolic changes seen when the thyroid is suboptimal is elevated cholesterol. Before you reach for a statin, which is associated with many health side-effects, get your thyroid correctly assesed and fix the root cause of the issue.

  • Cortisol: Saliva testing for cortisol upon waking (morning cortisol), before lunch, before dinner, and before bedtime is commonly used in the diagnosis and management of conditions related to adrenal function and stress, including adrenal insufficiency, Cushing's syndrome, adrenal fatigue, and burnout.

Naturopathic Thyroid Assessment Tools

As well as using blood tests, a naturopath may use additional assessment tools to evaluate thyroid health and function from a holistic perspective. While these tools complement conventional diagnostic methods, they focus on identifying underlying imbalances and promoting overall well-being.


Here are some commonly used naturopathic thyroid assessment tools:

  • Symptom Questionnaires: Comprehensive symptom questionnaires gather information about a patient's thyroid-related symptoms, including fatigue, weight changes, mood disturbances, hair and skin changes, temperature sensitivity, and menstrual irregularities. These questionnaires help identify patterns of dysfunction and guide further evaluation and treatment.

  • Iris analysis - iridology: Iridology examines the iris to assess overall health. The thyroid can be seen in the iris and levels of function assessed.

  • Thyroid Physical Exam: Naturopathic practitioners may perform a thorough physical examination, including palpation of the thyroid gland for size, shape, and tenderness. They may also assess for signs of thyroid enlargement (goiter), nodules, or other abnormalities. Physical findings, such as a diffusely enlarged thyroid or palpable nodules, can provide valuable diagnostic clues and inform treatment strategies.

  • Basal Body Temperature (BBT) Monitoring: Basal body temperature (BBT) monitoring as a simple and non-invasive tool to assess thyroid function. Patients track their body temperature upon waking each morning before getting out of bed. A consistently low body temperature may suggest hypothyroidism or thyroid dysfunction, although this method is not diagnostic on its own and requires interpretation in conjunction with other clinical findings.


  • Iodine Patch Test: The iodine patch test involves applying a small amount of iodine tincture to the skin and observing the rate of absorption. Naturopathic practitioners may use this test to assess iodine deficiency, as adequate iodine is essential for thyroid hormone synthesis. However, the iodine patch test has limitations and may not accurately reflect iodine status in all individuals.

  • Tongue analysis: Observation of the tongue is a useful physical assessment. Hypothyroid and iodine deficient states result in a fatter tongue with scalloping on the edges.

  • Functional Laboratory Testing: Functional testing provides insights into factors contributing to thyroid dysfunction and guides personalised treatment plans.

  • Nutritional and Lifestyle Assessment: Naturopathic practitioners emphasise the importance of nutrition, lifestyle factors, gut health, and environmental influences in thyroid health. They may conduct thorough assessments of dietary habits, stress levels, sleep patterns, toxin exposure, and other lifestyle factors that may impact thyroid function. Personalised recommendations for dietary modifications, stress management techniques, exercise routines, and environmental modifications are integrated into treatment plans to support thyroid health and overall well-being.


Thyroid Testing by Age

Optimal lab ranges may vary based on metabolic capacity, thyroid conversion, and the genetics of the individual. 


Many hormones naturally change production with age - for example when a woman transitions through menopause.


However, the thyroid should continue in the same optimal range as we age in order to preserve a healthy body. Even though thyroid hormones shouldn’t decline with age we do see a general decrease in thyroid hormone production and risk of thyroid disease in people as they age.


If you are interested in anti-aging, then looking after your thyroid should be number one priority!

Thyroid Levels Across Age Groups: Thyroid function tends to change with age. In younger individuals, thyroid hormone levels may be higher to support growth and metabolism, while in older adults, levels may decrease due to age-related changes in hormone production and metabolism. Therefore, what constitutes optimal thyroid levels varies across different age groups.


Lab Tests for Assessing Thyroid Levels: Several lab tests are used to assess thyroid function, including thyroid-stimulating hormone (TSH), free thyroxine (T4), free triiodothyronine (T3), and thyroid antibody tests. These tests help healthcare providers determine whether thyroid hormone levels are within the optimal range for an individual's age and health status.


Management of Thyroid Disorders: For individuals with thyroid disorders such as hypothyroidism or hyperthyroidism, achieving optimal thyroid hormone levels is essential for symptom management and overall health. Treatment may involve hormone replacement therapy, medication, dietary modifications, naturopathic interventions, gut and immune system support, and lifestyle changes.


Conclusion: Understanding the distinction between optimal and normal thyroid levels is crucial for assessing thyroid health accurately. While falling within the normal range may provide reassurance, it's essential to strive for optimal thyroid function to support overall health and well-being, especially as we age. Combining naturopathic care gives you access to full thyroid testing plus interventions to support your health and anti-aging goals.


Book a Free Discovery Call to discuss your health and ways that we can assist you to live your fullest life.



 

Author and Naturopath Tanya Kurzbock
Naturopath Tanya Kurzbock

Article written by Tanya Kurzbock

Naturopath registration ATMS#27459

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