Hypothyroidism | Underactive Thyroid

Underactive Thyroid

The thyroid governs the rate of metabolism of everything in the body, so when it is underactive, it generally causes slow, sluggish function throughout the body.

Signs and symptoms of low thyroid function can include:

• Fatigue, lethargy

• Brain fog

• Reduced cognition or memory

• Depression, anxiety

• Slow heart rate

• Reduced digestion (low stomach acid, constipation, bacterial overgrowths)

• Muscle aches and weakness

• Feeling the cold easily

• Weight gain or loss

• Low libido

• Insomnia

• Coarse, dry, congested skin

• Dry or thinning hair

• Joint pain or stiffness

• Brittle nails

• Loss of skin pigmentation

Thyroid Hormones & Lab Markers

TSH - Usually Elevated in Hypothyroidism

Thyroid stimulating hormone is made in the brain and released into the bloodstream in response to low levels of thyroid hormone, to stimulate the release of thyroid hormones T4 and T3. The brain detects the underactivity and attempts to restore balance.

T4 - Often Low in Hypothyroidism

T4 is thyroxine, the inactive form of thyroid hormone. It makes up about 80-90% of the total thyroid hormones. It needs to be converted to T3 before it can be used. Low levels of T4 show low production from the thyroid. If you're making any at all it means your thyroid is still capable of function and recovery, but this should be interpreted alongside the TSH result to understand how hard the thyroid is working for this result.

T3 - Often Low or Suboptimal in Hypothyroidism

T3 is triiodothyronine, the active form of thyroid hormone that affects cells. It is created through conversion of T4 to T3 by removing an iodine atom from T4, so good levels are reliant on both adequate T4 levels and good conversion. This conversion mainly happens in the liver, and is dependent on adequate selenium and zinc for the function of the deiodinasing enzymes. Very little T3 is directly made in the thyroid. Some conversion also happens in the other tissues including skin, kidneys, bones, brain and intestines. Low levels can be largely due to low T4 as the precursor, but through supporting conversion we can still help to increase the T3 levels.

Reverse T3 - Often low in hypothyroidism, due to low T4 precursor, but important to check as high RT3 can lead to similar presentation.

Reverse T3 is also produced through removing one iodine from T4 but it is an inactive form of T3. This inactive form is produced at an increased rate during times of major stress on the body - whether that be emotional stress, a demanding lifestyle, illness, low calorie intake or pregnancy. It is an adaptive mechanism for self preservation, slowing down function to conserve energy. High RT3 is not dysfunction as such, but maladaptation. Conversion to RT3 happens moreso in the peripheral cells rather than in the liver.

Free T3 : Reverse T3 Ratio 

This ratio shows whether your conversion to active, free T3 is higher in relation to your conversion to the inactive, reverse T3.

Thyroid peroxidase antibodies - Ideally we want these at zero, but they are often present at extremely high levels in hypothyroidism 

Thyroid peroxidase is an enzyme found in the thyroid gland that has important roles in T4 and T3 production. The presence of this confirms that your body is having an ongoing autoimmune response to this enzyme, mistaking your thyroid tissue as foreign and attacking it. The resulting destruction of tissue is the main contributor to low production of thyroid hormones. 

Anti-thyroglobulin antibodies and TSH receptor antibodies show whether your immune system is reacting to thyroglobulin (thyroid protein needed for T4 and T3 production) and your TSH receptors, and to what extent.

Abundant research shows that a gluten free diet can reduce antibody production significantly over a 6 month period. Molecular mimicry is the main mechanism understood to be responsible for this connection. The thyroid holds a heavy concentration of an enzyme called transglutaminase. Gliadin is one of the proteins that makes up gluten, and it has a very similar structure to transglutaminase, so the immune system can confuse them for being the same substance. Once the immune system is activated against either transglutaminase or gliadin, it will generally react to both substances in the same way, causing a much bigger immune response when gluten is present. Reducing gluten exposure allows the immune system to calm down which ultimately reduces the amount of antibodies reacting to the thyroid.

Thyroxine is a synthetic replacement for T4, the inactive thyroid hormone. While it cannot address the immune dysregulation causing the issue, it is still a valid medication in some cases if you are currently not making enough T4. It is still a bandaid hiding ongoing low thyroid hormone production but should be utilised while we work on controlling the immune response and allowing the thyroid cells to repair. The synthetic T4 still needs to be converted to T3 in order to have an effect on the cells and reduce symptoms. Liver support with herbal medicines can help with getting the best results out of Thyroxine.

Withania, tyrosine, zinc, iodine, selenium, rehmannia, bupleurum, hemidesmus and lemon balm are some of the remedies I use to treat hypothyroidism and Hashimoto's. Always seek professional advice before taking these as there are nuances to the reasons your thyroid isn't working and this understanding is what directs the selection of the best treatments.