Hypothyroidism in Women

Low thyroid function or hypothyroidism is far more common in women than men for two reasons:

1. Women tend to have seven times the possiblity of inheriting the autoimmune thyroid disease known as Hashimoto’s Disease (HT). HT is the most common cause of hypothyroidism and is characterized by gradual autoimmune mediated thyroid failure with occasional goiter development.
2. Effect of female hormonal imbalance: Estrogen dominance, a condition common in premenopausal women, is characterized by relatively higher levels of estrogen as opposed to progesterone. Relatively higher amounts of Estrogen cause the liver to produce a protein called “Thyroid Binding Globulin” orTBG. TBG has a tendency to bind to free and active thyroid hormone, making it inactive resulting in a decreased level of free and active thyroid hormone in the blood.

Unfortunately, the effect that estrogen dominance could have on the active thyroid hormone blood level cannot be picked up by routine blood work. Even though low thyroid function is an overwhelmingly female issue, many American women who experience the symptoms of possible low thyroid function (for instance: low energy, foggy brain, weight issues, high cholesterol) are not being properly evaluated and diagnosed, especially if the blood result is within normal range. This is in part due to the unfortunate fact that some of us as physicians, tend to be influenced by a type of herd mentality; instead of looking at, listening to and believing in the patient, we look at and believe in the lab results.
Later in this article, I will explain why blood tests are not very accurate by themselves in evaluating thyroid problems, but first let’s start with the basics.

Basic notes about thyroid gland and thyroid hormones

• The thyroid gland is one of the most important hormone producing glands in the body. It looks like a bow-tie and is located in front of the neck. A normal thyroid gland is not always palpable.
• T4 (thyroxine) is the main hormone produced by the Thyroid gland ( 93%). It is considered biologically and physiologically inactive.
• T3 (triiodothyronine) is another hormone produced by the thyroid gland (7%). It is considered biologically and physiologically active.

Our body cannot function with only 7% of active hormone, it needs more. The main source of T3 is the conversion of T4 ( inactive) to T3 ( active) which occurs outside the thyroid gland and inside cells such as muscle and liver. As a result, the T3 level measured in the blood is not a representation of total body T3. The level of T3 produced inside the cells will not show up in blood test.

Symptoms of Hypothyroidism:

• Fatigue, feeling cold, and weight gain: Thyroid hormone promotes the burning of the blood sugar as a fuel to produce energy. In the process of energy production the heat is produced and our metabolism increases. Then Hypothyroid, fatigue, weight gain and low body temperature will follow
• Depression, foggy brain, low concentration:Our brain is highly sensitive to thyroid hormone depletion, so patients with low levels of thyroid hormones often experience problems with mood and concentration
• Menstrual irregularity, low libido: Thyroid hormone imbalance leads to imbalances in female hormones as well
• Fertility impairment, miscarriage, premature delivery or still birth
• Elevated cholesterol: Synthesis of cholesterol as well as cholesterol absorption in the digestive system is increased in hypothyroidism
• Other symptoms such as: hoarseness, dry skin, constipation, brittle fingernails with ridging, low blood pressure, allergic disorders, hair loss, fluid retention, loss of hair on the outer edge of the eyebrows, tingling and/or numbness in extremities

Diagnosis of low thyroid function:

• Thyroid blood concentration varies throughout the day, so the lab test is a snapshot of what is going on in the blood at one moment in time.
• Thyroid blood levels can be affected by prescription drugs, imbalances in other hormones in the body ,as well as disease processes
• The “normal” laboratory range of thyroid hormones is an arbitrary number. It simply reflects the “normal” range for 90-95% of the population.
• The arbitrarily defined normal value has actually changed over time, for instance the normal laboratory range for the free thyroxin was lowered 15 percent from 1991-2001.
• Effect of aging on Thyroid gland function: with age the ability of our thyroid to make hormones declines.
• Blood values do not represent the production of active hormone or T3 inside the cell

General Treatment Notes

First, Please note that the data provided on this page is intended solely for general informational purposes and as such is NOT presented as a substitute for professional medical advice. You are encouraged to ALWAYS seek the advice of your physician or other health provider for questions related to your medical condition.
If low thyroid function is suspected in a patient with symptoms suggestive of low thyroid function, a blood test should be done. If the levels are abnormal (consistent with low thyroid function), the diagnosis is hypothyroidism and treatment should follow. If the lab results are normal, a trial of Thyroid medication -preferably combination of T3 and T4 such as Armour thyroid- can be started. In this case, the normal lab values will be used as a baseline and referenced later when follow up tests are done.