MAMIHOOD

Hypothyroidism in Women: An Underdiagnosed Epidemic

by: Alejandra Carrasco, M.D. and Christine Maren, D.O.

by: Alejandra Carrasco, M.D. and Christine Maren, D.O.

Physician founders of Hey mami!

If you’re reading this article, chances are you suspect you may have a thyroid problem.

Perhaps you’ve been experiencing symptoms like an inability to lose weight, mood swings, thinning hair, trouble sleeping, anxiety, or extreme fatigue.

And, up until this point you may have chalked this up to stress. Or you’ve checked a TSH (thyroid stimulating hormone) test, which came back within the normal range. Yet, your intuition tells you something’s not right.

Well, guess what? There is still a chance that something is not right.

Hypothyroidism is extremely common and under diagnosed in women. In fact “hypothyroidism affects up to 5% of the general population, with a further estimated 5% being undiagnosed.”1 And a condition known as subclinical hypothyroidism affects up to 10% of the adult population.2 That’s a lot of women struggling with low thyroid function!

Why?

Unfortunately, your thyroid is up against a lot of challenges in our modern world. And though TSH is the primary screening method for hypothyroidism, some would argue that measuring a TSH alone is not sufficient (more on this below).

As you dig a little deeper into the intricate function of the thyroid, you quickly realize that one test cannot possibly account for all the hormonal factors and pathology at play.

In addition, the symptoms of hypothyroidism are vast and can appear random.

The Symptoms of Hypothyroidism

  • Fatigue
  • Depression
  • Brain fog
  • Constipation
  • Dry skin, rashes, mysterious skin conditions
  • Brittle nails
  • Weight-gain and/or an inability to lose weight
  • High cholesterol
  • Thinning or coarse hair
  • Inability to focus
  • Low libido
  • Anxiety
  • Sluggishness in the morning
  • Sensitivity to cold
  • Cold hands and feet
  • Insomnia
  • Muscle pain
  • Fluid retention
  • Thinning eyebrows
  • Hormonal imbalance
  • Mood swings
  • Irregular or painful periods
  • Low heart rate

Comprehensive Thyroid Labs

If we suspect a patient is suffering from postpartum thyroid issues (or any type of thyroid issue), we order 6 different thyroid lab tests:

  1. TSH: though not the end-all-be-all test, it does provide valuable information. TSH is a regulatory hormone, secreted by the pituitary gland (in your brain) to stimulate the thyroid gland to produce T4 and T3. High levels of TSH may mean hypothyroidism.
  2. Free T4: T4 is secreted by the thyroid gland, and the majority of T4 is converted to active T3 for metabolic functions and energy. Low levels of free T4 may mean hypothyroidism.
  3. Free T3 (“the gas”): T3 is the more active form of thyroid hormone that affects your metabolism and energy. Low levels can indicate hypothyroidism or a problem with conversion.
  4. Reverse T3 (“the brakes”): Reverse T3 is also converted from T4 and basically helps slow down metabolism. Factors that increase conversion of T4 to reverse T3 (i.e. the things that make you slam on the metabolic brakes) include stress, trauma, low-calorie or crash dieting, toxins, infections, inflammation, and certain medications.3
  5. Thyroid Peroxidase (TPO) antibodies: This test is to check for autoimmune disease of the thyroid known as Hashimoto’s.
  6. Thyroglobulin (TG) antibodies: This is another marker for autoimmune disease of the thyroid.

Due to the complex nature of thyroid hormones, accompanied by the increased prevalence of hypothyroidism and Hashimoto’s Disease, these six labs are useful tools for achieving an accurate diagnosis and optimizing medication management.

The timing of these tests is important, too. If you are already on a synthetic T4 medication like Synthroid or Levothyroxine, we usually recommend labs are drawn first thing in the morning prior to taking your medication. However, if you are taking a medication with T3 (such as Armour or Cytomel), then we like to have these labs checked 4-6 hours after taking medication so that we can better understand T3 levels. Check with your doctor on this one.

If your doctor can’t order these tests for you, then you can order these yourself or find a doctor who will. To be clear: we are not suggesting you ignore your labs or disregard your physician’s advice… But we want you to be able to advocate for yourself so that you can get answers and get better. And also – it’s not always your thyroid! If you can find a doctor who will work with you on this, they can help uncover other reasons for your symptoms.

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What is Hypothyroidism in the first place?

Hypothyroidism is a clinical state resulting from the underproduction of the thyroid hormone.4

There are a few definitions to be aware of that are well recognized in the medical literature:

  • Overt primary hypothyroidism usually presents with a high TSH and a low free T4. The most common cause of this among women in the United States is an autoimmune disease called Hashimoto’s.
  • Subclinical hypothyroidism on the other hand, presents with a high TSH and a normal free T4.5 Many of the people with subclinical hypothyroidism eventually develop overt hypothyroidism, but are often left untreated until then.
  • Euthyroid Sick Syndrome refers to alterations in low free T3 following severe illness, calorie deprivation, and following major surgeries.6,7. This is not technically an issue with the thyroid gland, but more of a systemic issue with poor conversion. The most common pattern is a low total T3 and free T3 levels with normal T4 and TSH. It has also been referred to as Nonthyroidal Illness Syndrome, Low T3 Syndrome and Wilson’s Temperature Syndrome.
  • Autoimmune Thyroiditis refers to a chronic autoimmune disease – either Hashimoto’s or Grave’s – in which the immune system makes antibodies against the thyroid gland and thyroid hormones. These may include Thyroid Peroxidase (TPO) antibodies, Thyroglobulin (TG) antibodies, and TSH receptor Antibodies (TRAb). This may result in hypothyroidism or hyperthyroidism. But to be clear, this is an immune system problem, that over time alters thyroid function.

Thyroid issues also frequently arise postpartum, which is one reason we feel strongly that women should be screened for this after birth, especially if there is postpartum depression.

And we’re not the only ones. The 2017 Guidelines of the American Thyroid Association state that all patients with depression, including postpartum depression, should be screened for thyroid dysfunction.8 But, again, you will likely need to advocate for all 6 of the tests we outlined above.

What Causes Hypothyroidism?

Beyond pregnancy, pre-existing conditions, radiation, genetics, and congenital disease, other causal factors behind hypothyroidism include:

  1. Autoimmune Thyroid Disease: in Hashimoto’s Disease the immune system destroys thyroid tissue and causes low thyroid function over time.9
  2. Nutrient deficiencies: Production of thyroid hormones relies on adequate nutrients, including iron, iodine, tyrosine, zinc, selenium, vitamin E, C, D and many of the B vitamins. Vitamin A is also important as it improves cellular sensitivity to thyroid hormones.
  3. Tap water containing fluoride and chlorine: Iodine is critical to the production of thyroid hormones. Both fluoride and chlorine can displace iodine from your thyroid, rendering it less effective.10 Fluoride has been shown to disrupt thyroid hormones, even in the standard concentration of less than 0.5 mg/L.11 This is yet another reason we recommend good household water filtration.
  4. Celiac disease: Research has shown that removing gluten from the diet may single-handedly reverse subclinical thyroid conditions in adult patients with newly diagnosed celiac disease.12
  5. Heavy metals: many types of heavy metals are found in our environment, like mercury, arsenic, cadmium and lead. High mercury levels, specifically – which are common in dental materials and large fish like tuna – can lower thyroid hormones.13
  6. Stress: too much stress can cause major thyroid hormone imbalance.14 Stress not only inhibits the production of thyroid hormones, it also tends to increase conversion of T4 to reverse T3, an unusable form of thyroid hormone. For this reason, we often recommend meditation to help you better handle stress, and also adaptogenic herbs like Ashwagandha. In one small study, patients treated with Ashwagandha had an increase in T4.15
  7. Endocrine-disrupting chemicals: many toxins commonly come from pesticides and plastics and interfere with a variety of thyroid functions.16
  8. Medications: Lithium, iodine and amiodarone may all cause issues with thyroid function.17 Of note: while iodine deficiency can cause hypothyroidism, excessive iodine supplementation may also cause issues.

Why Many Thyroid Issues Go Undiagnosed

In our experience as clinicians, there are many people with subclinical thyroid function and even overt hypothyroidism who are undiagnosed and thus left untreated — which leaves a big gap for people who are experiencing the symptoms of hypothyroidism.

This is in large part because as commercial TSH assays have become more sensitive, many doctors have adopted TSH as the one-and-only test to diagnose hypothyroidism. While TSH is clearly a clinically useful parameter, it has some limitations. This is well summarized in The Journal of Thyroid Research:

While using TSH as a singular test to screen for hypothyroidism “has been successful in many ways, it has some grave limitations. This includes the basic question of what constitutes an agreed reference range and the fact that the population-based reference range by far exceeds the variation of the intraindividual set point. Both problems result in a potential misdiagnosis of normal and pathological thyroid function in a substantial proportion of patients.”18

Let’s break that down.

First, the normal lab ranges for TSH have been debated for years, but remain mostly unchanged. The upper limit of normal is around 4.5 mIU/L depending on the lab, but many (including published work in the National Journal of Clinical Endocrinology and Metabolism) have suggested a narrower TSH reference range with an upper limit of 2.5 mIU/L is more appropriate.19 The point is: lab reference ranges are not perfect, and people with a TSH > 2.5 may be missing an important diagnosis.

Second, we would agree with a more personalized interpretation of thyroid test results, because you are more than your labs. Don’t get us wrong, we don’t think you should ignore your labs. But perhaps a population-based reference range is different than your ideal reference range as an individual, and some people don’t feel great with a TSH of 4.

Be sure to download our free lab guide to better understand the reference ranges we use with patients in our clinical practices.

And what’s not mentioned above is the large subset of patients with Hashimoto’s who don’t get tested for TG and TPO antibodies – which means that if there’s another underlying issue, such as autoimmune thyroid disease, it goes unnoticed.

We feel strongly about educating you on this matter because thyroid medications can be life changing for some. And when you consider the side effect profile of thyroid medication – when prescribed responsibly and monitored – it is much safer than many other medications (like cholesterol reducing medications and antidepressants, for instance).

The big takeaway…

If you suspect you have a thyroid problem, consider checking a more comprehensive panel.

It is imperative that you be your own advocate if you want to figure out what’s going on with your body, especially if the answers aren’t adding up.

No mami needs to be stuck “surviving” on fumes and feeling like crap all the time. Yes, sometimes feeling like crap-warmed-over is inevitable (especially when the kids wake you up three times on the one night you decided to binge watch your favorite show with a half a bottle of wine) but feeling that way all the time? No way. That’s not normal, and it’s no way to live your life.

So, trust your intuition, get those tests run, and find appropriate care if they come back out of range.

Be sure to download our free lab guide to better understand the reference ranges we use with patients in our clinical practices.

What if your tests all come back as optimal? Then keep digging. Find a functional medicine physician to work with you to look for other issues including mitochondrial dysfunction, undiagnosed Celiac disease, iron deficiency and hormone imbalances.

References:

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822815/
  2. https://pubmed.ncbi.nlm.nih.gov/31287527/
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6917573/
  4. https://www.mayoclinic.org/diseases-conditions/hypothyroidism/symptoms-causes/syc-20350284
  5. https://jamanetwork.com/journals/jama/article-abstract/2737687
  6. https://www.ncbi.nlm.nih.gov/books/NBK482219/
  7. https://www.ncbi.nlm.nih.gov/pubmed/9086580
  8. https://www.ncbi.nlm.nih.gov/pubmed/28056690
  9. https://www.thyroid.org/hashimotos-thyroiditis/
  10. https://onlinelibrary.wiley.com/doi/abs/10.1002/0471435139.tox048
  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5805681/
  12. https://www.ncbi.nlm.nih.gov/pubmed/11280546
  13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3569681/
  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3079864/
  15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4296437/
  16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5751186/
  17. https://www.aafp.org/afp/1998/0215/p776.html
  18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3529417/
  19. (https://academic.oup.com/jcem/article/98/9/3584/2833082

Our Bio

We are doctors Alejandra Carrasco M.D. and Christine Maren D.O. We’re board-certified through the American Board of Family Medicine, and certified in functional medicine through the Institute for Functional Medicine. We’re on a mission to support women as they navigate mamihood—from preconception through pregnancy, postpartum, and beyond. As mamis of 3 (each!), we got you.

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