Prior to synthetic thyroid hormones being commercially available as a product, (aka Levothyroxine, or “Synthroid” and Liothyronine or, “Cytomel”) thyroid hormone replacement therapy was available in a product form called Desiccated Thyroid or “DTE”. I jokingly call “DTE” the “Original Organ Meat” because DTE traditionally refers to a dried porcine (pig) gland and it has been around since the 1890s. Side note: this is why DTE is not technically FDA approved… because it predated the existence of the FDA entirely! Examples of common day DTE options include the brand names: NP Thyroid, Armour Thyroid, Nature Thyroid and off-label compounding pharmacies own formularies marketed as, “Desiccated Thyroid”.
What is the distinction between DTE and synthetic thyroid hormone replacement therapy? Well, DTE and synthetic thyroid hormone products differ in molecular weight, chemical composition and mechanisms of actions. DTE contains a full thyroid gland’s ingredients, meaning it includes elements of T4 and T3 along with a little bit of T1 and T2. Most DTE products produced on the market contain T4 and T3 in an approximate ratio of four T4 to one T3. For instance, a single 60mg NP Thyroid pill will contain 38mcg of T4 and 9mcg of T3. Side note: some compounding pharmacies make their own DTE to manipulate the T4/T3 and T1/T2 ratio quantities more uniquely. Brand name DTE pills are most commonly available in 15-120mg dosages each.
Synthroid/Levothyroxine only contains synthetic lab-created T4 and Cytomel/Liothyronine contains only synthetic lab-derived T3. NOTE: for the purpose of this article, we will continue to refer to synthetic T4 and T3 products by their Levothyroxine and Liothyronine names alone. Levothyroxine and Liothyronine come in static forms of T4 and T3 micrograms each: ie. Synthroid is available in 25, 50, 75, 88, 100+ mcg of T4 pills etc while Liothyronine comes mostly commonly in ranges of 5-25mcg forms of T3 pills.
It is common practice to take Levothyroxine (synthetic T4) first thing in the morning, never in the afternoon. This is because Levothyroxine contains only T4, as its purpose is to provide an “extended release” form of thyroid activity. Recall, the premise of Levothyroxine is that its T4 content can be converted into “immediate release” T3 when your body physically demands it. Levothyroxine’s total duration of action, or shelf life in your blood stream circulation, is approximately 2 weeks long.
Liothyronine (synthetic T3) can also be taken in the morning. Liothyronine has a quick absorbency and its shelf life is hours, not days, unlike Levothyroxine. Thus, while it provides an instantaneous array of thyroid functions and does not rely on the conversion of T4 into T3, its disadvantage perhaps, is that it clears quickly from the body. Occasionally, you will see a medical provider prescribe Liothyronine twice daily, once in the morning and once in the afternoon, in effort to provide consistency in blood levels of T3 to their clients. However, medical providers have generally moved away from selecting this “rapid release” form of thyroid hormone as first line replacement therapy – deeming it as “unstable” or “unreliable” for use due to its instantaneous impact but swift decline of effective stability.
Side note: it should be known that compounding pharmacies can also make combination forms of Levothyroxine & Liothyronine pills, in which case a client will intake both synthetic T4 and T3 in the morning – but we will not discuss this option much at this time.
Desiccated thyroid hormone replacement therapy (DTE) is classically prescribed to be taken in the morning, just like its synthetic hormone competitors above. However, because DTE contains both a combination T4 and T3 – there exists a permissive license to use it twice daily for dosing. Why? While ingesting T4 and T3 in the morning will provide both extended and immediate thyroid symptom relief, the T3 component of DTE expires rapidly (as it does with Liothyronine). Thus, providing a second, early afternoon DTE dose may strategically stabilize the patient’s hypothyroid symptoms by supplying a consistent (round the clock) supply of T3.
Now, circling back now to our post-thyroidectomy client: What are his/her options when it comes to thyroid hormone replacement therapy?
Levothyroxine, certainly. Perhaps, Liothyronine. However, we can also employ – DTE, used once daily or BID. Most insurance companies will dictate the need for a client to use and prove “failure of therapy” with Levothyroxine as a first-line strategy. Don’t ask me why – ask the insurance companies. However, not all clients will feel well-mitigated symptomatically while being on T4 alone, as they may be missing out on their need for achieving healthy levels of circulating T3.
So, as a bioidentical hormone therapy replacement provider, I firmly believe that not one size fits all when employing pharmaceutical strategies for hypothyroid patients. However, it wasn’t until I studied functional medicine that these varying pharmaceutical options came into understanding for me.
When I was a practicing hospitalist physician assistant, I recall asking an attending physician – who was at least fifteen years senior to me – “What is this medication, titled Armour Thyroid”? Because in physician assistant school, I had not come across it before (as it was not taught to me). And as I looked at its RX signature, “Armour Thyroid, 60mg BID dosing” on a client’s intake sheet, verbatim, the attending physician replied, “Oh, it’s just an antiquated thyroid med – we don’t use those things anymore”. No further explanation was given. No mechanism of action was described. His answer was simply, “That medication has aged out of use and purpose” and “We don’t deal with those things”.
The stunning revelation to me, reminiscing back towards the time frame of that conversation, is that it was actually common practice amongst practicing hospitalist practitioners to revoke patients’ Armour Thyroid, NP Thyroid or Nature Thyroid medications, the “Desiccated Thyroids” if & when they came though our ER and Medical/Surgical floors. We would in fact, switch patients’ predominantly onto Levothyroxine for the entirety of patients’ hospital stays. This wasn’t done of “spite” but rather under the tutelage that using Levothyroxine was, “best medical practice” and likely, the main thyroid drug on formulary within the hospital pharmacy. (Caveat: Levothyroxine is one of the only forms in which thyroid hormone replacement therapy can be administered intravenously. So, there is a selective strategy to use this compound if someone cannot tolerate an oral route of medications for a period of time). However, for those who could tolerate oral routes, I now shake my head sometimes, reflecting back on that – slightly chagrined at acknowledging how the marked differences in DTE vs. synthetic thyroid hormone product chemistries and their applications can impact clients’ clinical outcomes.
So, if you struggle with hypothyroidism, talk with your provider or call us here at Kalon West | Bioidentical Hormone Replacement Therapy Clinic. Perhaps it’s time to switch up your pharmaceutical thyroid strategy by trialing a little T3, considering BID dosing or using custom compounded thyroid formularies. There are multiple solutions for every situation and we believe in our Kalon West team to help you select the right thyroid hormone replacement strategy.