Thyroid Thursday Episode 37: Is Normalized TSH Synonymous With Euthyroidism In Monothyroxine Therapy?
For many people who’ve been diagnosed with hypothyroidism and placed on T4 monotherapy, their struggle with hypothyroid symptoms continues despite the normalization of their TSH. A recent paper published in the Journal of Clinical Endocrinology and Metabolism indicates the persistent hypothyroid symptoms can persist even when a person has normalized TSH and T4 levels with T4 for therapy.
This paper gives validation to millions of people who are taking T4 therapy (Synthroid, Levothyroxine) who continue to struggle with hypothyroid symptoms. Too often, doctors focus only on what TSH and T4 values are, believing if TSH and T4 are normal, thyroid hormone physiology is fixed.
The patients remaining symptoms are often considered to be separate conditions, and they are placed on additional medications to suppress the signs and symptoms.
The paper points out that those taking T4 therapy tended to be 10 pounds heavier despite lower caloric intake, 30 to 40% more likely to be on beta blockers for elevated blood pressure, statins for elevated cholesterol, and antidepressants when compared to healthy non-hypothyroid adults.
What should be gleaned from this paper is that normalization of TSH and T4 levels don’t necessarily normalize thyroid hormone physiology and all tissues.
Providing T4 therapy can normalize TSH and T4. It can reduce hypothyroid symptoms for many people. For 10 – 15% of the 10 million Americans diagnosed with hypothyroidism and placed on T4 therapy, they may continue to have hypothyroid symptoms despite normal TSH and T4. Also, providing T4 therapy alone never addresses the “cause” of why a person has hypothyroidism. When cause isn’t addressed, we become slaves to the medication, often allowing the same destructive forces that cause thyroid physiology dysfunction to impact other tissues as well.
Thyroid hormone physiology is more complex than just providing T4 hormone. T4 must be converted to a more active hormone, T3 within many tissues to support metabolism. The transport of T4 into cells and conversion to T3 can be influenced by many factors.
Providing T4 and assuming all the downstream chemistry will work is like assuming because you put gas in your car that it will run perfectly. The gas gauge could be full, but what if there is a hole in the gas line, bad spark plugs, a bad alternator, low oil, or a broken belt? The car won’t run well, and maybe not at all.
The same holds true for thyroid hormone physiology. Just because you topped off the tank with thyroid hormone and your TSH and T4 blood levels look normal, does not mean you’ve normalize cellular function.
Your persistent symptoms are not in your head. Your persistent symptoms are indicators of abnormal cellular thyroid hormone function. Find a functional medicine specialist to help you uncover why your hypothyroid symptoms persist.