Hello, I have a question about thyroid disorders and the treatment prescribed. I have hypothyroidism as indicated through TSH and t4 labs. I trust my doctor who says I need to supplement with levothyroxine. Since my dx, I've found a couple of on-line support groups that on the one hand are helpful because I can bounce things around with members. On the other, I get so much conflicting input, that sometimes confuses me more than it helps. It seems TSH is the gold standard for determining hypothyroidism. Treatment is Synthroid or another version of it. No other tests are routinely ordered; no supplements typically recommended.
Why then, are their die hards who think FREE T-3 (caps for emphasis on purpose), FREE T-4 and say that TSH doesn't matter at all? It is also suggested that B12 and Vitamin D MUST also be tested. Members suggest paying for labs privately and taking them to docs or demanding their doc do these labs. So, who is driving this line of thought? Its like denying global warming or something. Some group members simply deny standard medicine procedures. Why?
Dear An: I hear you, and I would like to give my OPINION, but I'm out of time today. Check back. Hopefully other readers will give their input as well as your question makes an excellent departure point for discussion.
Thanks for your Reply!
I actually started typing a reply this morning but then decided against it. But here's my input.
TSH is actually a pituitary hormone that stimulates the thyroid gland to secrete T4. It's my understanding that T4 then converts to T3 which is the active form used by the body for metabolism. Some believe that TSH is a poor indicator of thyroid function since it's really just a "messenger." And that the hormones produced by the thyroid (T4 directly and T3 indirectly) are better indicators of thyroid function. And it's the FREE forms of these hormones that are available for the body to use so those are the ones that should be tested.
Additionally, some believe that the T4 to T3 conversion process doesn't work properly. This would be reflected in the FREE T3 serum level. If the FREE T4 level is "good" and the FREE T3 level is low then a T4/T3 (natural dessicated) thyroid medication may be a better treatment than T4-only (levythyroxine). And there are people who say that switching to a T4/T3 med made a big difference in treating their hypothyroid symptoms.
This makes sense to me but it seems that most doctors (even endocrinologists) don't buy it. I know it can take some time to change medical teachings so maybe it just hasn't "taken hold" yet?
Dear All: Anon_6061 has given a superb summary of the basic science behind thyroid testing. The best explanation as to why most MDs/endocrinologists prefer T4 as medication (eg levothyroxine) was posited by a PharmD candidate. I'll quote directly, then provide the link to the source:
Armour Thyroid (desiccated porcine thyroid gland) and Synthroid (levothyroxine) are used as replacement therapy for thyroid hormone when the thyroid is under-active, nonfunctioning, or has been all or partly surgically removed. The thyroid hormones naturally produced in your body are liothyronine (T3) and levothyroxine (T4). These hormones are necessary for metabolic regulation, normal growth, development, and mental function, among other things. T4 is found in the body at approximately four times the level of T3, but T3 is four times more potent. T3 is the active thyroid hormone used in the tissues, whereas T4 is a storage form that is stored in the liver, converted to T3 as needed. This storage mechanism acts as a buffer to help the thyroid keep up with the body's demand for thyroid hormones. The controversy over whether to use synthetic versions of thyroid hormone (Synthroid, Levoxyl, et al.) versus natural forms (Armour Thyroid) is better stated: "whether to use T4 alone or a T3 and T4 combination." Armour Thyroid was the only treatment for hypothyroidism for about 50 years, but it was found that the amounts of T3 and T4 varied greatly from batch to batch. Eventually, synthetic T4 (Synthroid) was being produced and widely used because it did not have similar problems of standardization in common with the naturally derived Armour Thyroid. A disadvantage of Synthroid is that some patients do not feel quite as well on T4 alone as they do on T3/T4 combinations. This is thought to be because not all tissues have the ability to convert T4 to T3 equally, such as brain tissue. In order to compensate for this, physicians may over medicate patients with T4 in order to compensate for this conversion problem. This may lead to greatly increased T4 levels, resulting in a temporary hypothyroid condition. Synthetic T4 products have not been shown to produce permanent hypothyroidism, though most patients return to a normal thyroid state soon after stopping the medication. In some patients, combination products may be better than single T4 products, because of a lack of ability to convert T4 to T3. In recent years, a synthetic T3/T4 combination (Liotrix) has been developed to deal with the problem of standardization of the Armour Thyroid. However, Liotrix is more expensive than either Synthroid or Levoxyl, and remains the reason why most therapy for hypothyroidism is initiated with these agents. Prepared by Jed Oyer, PharmD candidate.
In my clinical practice I would start a patient on T4 (eg levothyroxine) because this is not my area of expertise. Community standards of medical practice (as Anon_6061 points out) are to use standardized T4 rather than "natural" dessicated animal thyroid. To be sure there are individual differences in metabolisms of all drugs, but we tend to start with standardized regimens---even with antibiotics and birth control.
With Respect, Jane
Thanks for your Reply!
Thanks Jane! As far as PharmD' candidate Oyer's comments "In order to compensate for this, physicians may over medicate patients with T4 in order to compensate for this conversion problem. This may lead to greatly increased T4 levels, resulting in a temporary hypothyroid condition. Synthetic T4 products have not been shown to produce permanent hypothyroidism..." I suspect he meant hypErthyroidism not hypOthyroidism.
Liotrix (mentioned by Oyer) is Thyrolar which I've heard of but most on thyroid forums prefer the natural dessicated T4/T3 but don't know how many have ever used Thyrolar. There's a fairly new natural dessicated T4/T3 med made by Acella called NP thyroid which seems to be preferred over the reformulated Armour for fans of T4/T3.
Thanks for your Reply!
Hey forgot to mention - I've read that people who're hypothyroid tend to have "low" ferritin (storage iron) levels. It seems B12 can also be an issue which may be due to a tendency to lack intrinsic factor for B12 absorption. I don't recall reading anything about a link between vitamin D levels and hypothyroidism. Hypothyroids also tend to have high cholesterol.
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