By Dr. Justin Marchegiani
When thyroid hormone levels are low (hypothyroidism), your body doesn't break down and remove LDL cholesterol as efficiently as usual. LDL cholesterol can then build up in your blood. Even people with mildly low thyroid levels, called subclinical hypothyroidism, can have higher than normal LDL cholesterol.
Without enough thyroid hormone, many of our bodily functions begin to slow down (weakened metabolism), and our body temperature tends to drop. Thyroid hormone is essential to health and is needed to help break down the building blocks (cholesterol) of our hormones into our active hormone constituents such as estrogen, cortisol, progesterone, and testosterone. If there is an inability to break down our hormonal raw material on the front end, we tend to see a decrease in supply of hormone on the back end. This can create a bottleneck regarding our body's ability to create hormones.
Healthy hormone balance helps keep our body in a healthy anabolic state, where we can heal and stay youthful versus breaking down and staying inflamed or in pain.
Imagine you are a construction worker trying to build a house. You tell your foreman you needed 100 pieces of wood to build the frame of a house, but you show up the next day and have only 50 pieces of wood at the construction site. What do you do? When it comes to your body's inadequate levels of thyroid hormone, it will be difficult to have optimal hormonal balance, control inflammation, and produce energy until this problem is fixed.
“Patients who have been diagnosed with high cholesterol should ask their physician about having their thyroid checked. If they have an underlying thyroid condition in addition to their high cholesterol, the cholesterol problem will be difficult to control until normal levels of thyroid hormone are restored.”
~Richard A. Dickey, MD
Below I am going to break down some of the science proving that thyroid function has an effect on our lipid and cholesterol levels. If you feel overwhelmed, just take a deep breath, and as long as you understand the key concepts, you are on the right track.
Thyroid hormone has influence on a compound known as cholesteryl ester transfer protein (CETP) activity, which converts cholesterol esters from high-density lipoprotein (HDL) to very low-density lipoprotein (VLDL) and helps with the break down of triglycerides.
Thyroid hormone also has an effect on the lipoprotein lipase, which helps break down triglycerides and helps convert HDL into intermediate-density lipoprotein (IDL) compounds.
T3 thyroid hormone also helps up-regulate apolipoprotein AV. Apolipoprotein AV helps regulate triglyceride metabolism. With adequate levels of T3, our body has the ability to help keep our triglyceride levels at a healthy balance.
Thyroid Hormone Affects Our Genes!
T3 also has an effect on the thyroid hormone response elements (TRE's). On the left side of the picture below, TRE is circled. The TREs impact the expression of the LDL gene receptor site. With adequate T3 levels, it also protects the LDL cholesterol from oxidation. It's almost as if adequate levels of thyroid hormone are an antioxidant. This is important because cholesterol helps create a healthy cell membrane, keeping it fluid, flexible, and stable.
Adequate levels of thyroid hormone are shown to help with insulin sensitivity. With hypothyroidism, insulin resistance goes up. As our body makes more insulin, this can stimulate our liver to make more cholesterol. By regulating thyroid function and blood sugar, we have a direct effect on our body's ability to produce cholesterol.
We have two types of thyroid hormone, generally speaking: T4 and T3. Consider T4 a storage hormone—its metabolic effects on the body are insignificant. Consider T3 your active thyroid hormone—it is four times more potent than T4. Most people only get their thyroid assessed using a few specific lab markers, including thyroid stimulating hormone (a brain hormone) and maybe T4. The most important hormone of them all is T3, which is very rarely assessed, and it's free and total fractions. But again T3's what has the real metabolic effect on the body.
We mention that thyroid hormone has an effect on our metabolism. A simple way to measure our metabolism is via body temperature. With healthy thyroid function, your body temperature should be between 97.8°F and 98.2°F in the axillary or armpit area.
Body temperature does go off slightly if you are measuring it via your mouth or oral area. In your mouth, normal body temperature should be between 98.2°F and 98.6°F. If your body temperature is in this range, this is a good sign that you have adequate thyroid function.
These are simple assessments you can do at home without getting any blood work just to see how your thyroid function is doing. Again, it's possible to have low body temperature and not have it be purely a thyroid issue. Many other issues can cause low body temperature, including chronic infections, adrenal fatigue, and anemia to name a few. Many thyroid conditions are autoimmune in nature, which is when your immune system begins to attack it's thyroid tissues. Both situations call for different measures of treatment to ensure success.
A good functional-medicine doctor will rule out all of these things one by one to make sure nothing is missed. To get assessed, click here!