Why Levothyroxine May Not Work For You


Are you taking generic supplemental thyroid hormone levothyroxine or brand Synthroid?  Do you still believe that you may be hypothyroid (low in the thyroid hormone) because you have the symptoms of brain fog, hair loss, fatigue, weight gain, low libido, constipation, dry and itchy skin, puffy face, depression, impaired memory, and many more?

Read below why levothyroxine may not be the best option for you, even though your lab results look great!

So, here it goes: Follow me as I go down explaining the chart on the left.

1. The part of your brain (hypothalamus) makes TRH – Thyroid Releasing Hormone and sends it down to another part of the brain called Anterior Pituitary Gland => thus, TSH – Thyroid Stimulating Hormone is made. TSH does what it is supposed to do, the name speaks for itself: TSH stimulates the thyroid to produce thyroid hormone Free T4 (Thyroxine) which is turned into an active thyroid hormone Free T3 (triiodothyronine).

If your thyroid makes enough Free T3 (the active hormone that your body uses), the NEGATIVE FEEDBACK LOOP triggers and the parts of your brain (pituitary and hypothalamus) are starting to relax = your pituitary stops making TSH (Thyroid Stimulating Hormone) because there is enough active free T3 thyroid hormone in your body! Why bother working harder if there is plenty of active free T3?

But there is one of many caveats when it comes to thyroid: your free T4 needs to be converted into an active free T3 that each cell of your body can use! As you see in this chart, Free T4 may be converted into Reverse T3 and your Free T3 will be low. Your Reverse T3 is hijacking your Free T3 and your body cannot use Reverse T3!

So, here are some suggestions, in case your levothyroxine does not work or stopped working and you experience hypothyroid symptoms.

  1. First of all, TSH does not show the full picture of your thyroid function. It is just one of the components, not the whole puzzle.
  2. Secondly, ask your healthcare provider to test for TSH, Free T4, Free T3, and Reverse T3. The antibodies can be helpful.
  3. If your Free T3 low, but TSH is optimal (between 1-2 optimally), you still may be hypothyroid and need a little bit of T3-only medication (for example, liothyronine or Cytomel) in addition to levothyroxine.
  4. At times, your Free T3 can be low due to high Reverse T3 (<13) which is elevated due to physical, emotional, mental/psychological stressors. Some of the most common ones are overexercising (CrossFit training, HIIT 7 times a week for 30-60 minutes), intense dieting and calorie restriction, high amounts of stress.
  5. Your Reverse T3 should be low, Free T3 should be in the upper 25th percentile of your lab reference range. Meanwhile, TSH may be suppressed and be < 0.5.
  6. There is no one size fits all. Some people do better with levothyroxine and Cytomel/liothyronine – a synthetic form of T3. There are two options for liothyronine – a quick-release form liothyronine and sustained-release liothyronine (T3) that can be compounded at one of the compounding pharmacies.
  7. Natural Desiccated forms of thyroid hormone have both biological forms of T4 and T3 (9 mcg of T4 and 38 mcg of T3 per 1 grain). Some people do much better on Natural Desiccated Thyroid (NTD) hormone, such as Nature-Throid, Armour-Throid, WP Throid.

Why then not so many healthcare providers go off the lab results and not patient’s symptoms? Why not only a few healthcare practitioners check the full thyroid panel including Reverse T3?

It is 2018, but we have only 2012 guidelines from the American Thyroid Association…


“Serum thyrotropin (TSH) is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations, but it is not sufficient for assessing hospitalized patients or when central hypothyroidism is either present or suspected.” “The standard treatment is replacement with L-thyroxine which must be tailored to the individual patient.”

“A serum thyrotropin is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations. The standard treatment is replacement with L-thyroxine. The decision to treat subclinical hypothyroidism when the serum thyrotropin is less than 10 mIU/L should be tailored to the individual patient.

The Guidelines for the Treatment of Hypothyroidism Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement from 2014 made the following conclusions:

“Conclusions: We concluded that levothyroxine should remain the standard of care for treating hypothyroidism. We found no consistently strong evidence for the superiority of alternative preparations (e.g., levothyroxine– liothyronine combination therapy, or thyroid extract therapy, or others) over monotherapy with levothyroxine, in improving health outcomes.”

And that is the reason that many patients have been prescribed levothyroxine because it is considered superior to other thyroid medications. I personally cannot even describe the difference that Natural Desiccated Thyroid made in my life compared to levothyroxine. Every person is unique! What worked for me may not work for you and vice versa. Putting everyone into one guideline category of TSH >10, is not what helps patients get better. It is up to a clinician to decide if treatment should be even considered if TSH is less 10, depending on the symptoms. But symptoms could be so vague and, at times, you may not even remember how good you felt before you got sick, because a lot of times you felt good such a long time ago that it is hard to remember! With my TSH 4.47 I thought I felt ok and normal for my age. Now that my thyroid hormone levels are optimal, my energy is up, weight is down, brain fog is GONE!

One more point: The new 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum recommend TSH < 2.5 for pregnant women… Why such a broad difference between the recommendations for pregnant and non-pregnant women or adults? Why are the risks so high for pregnant women and their babies if their TSH > 2.5, but the risks for other non-pregnant adults are deemed non-significant? Just food for thought.




Should you need more help with getting to the underlying cause of your fatigue, insomnia, thyroid and hormonal problems, schedule a consultation with Zhanna Tarjeft, FNP Here.

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