thyroid labs / medication regimen

[RCinNY]

Hi, all.  I've posted previously about being fatigued for likely a few reasons, although I've improved somewhat lately.  I'm seeing an endo who's willing to try to get my thyroid levels (at least TSH) from "within the range" to "optimal" to see if it helps.

My labs went from
TSH   3.49 (0.4-4.5) before treatment --> 8 weeks of 25 levothyroxine 2.28 --> 8 weeks of 50 levo. 2.02
free T4   1.2 (0.8-1.8) --> 1.9 --> 1.6
free T3   2.9 (2.3-4.2)  --> 2.66 (2.1-4.4) --> 2.64

While the TSH and FT4 definitely improved almost immediately, FT3 still seems to be lagging (conversion problem not brought up yet).  I thought it was more curious that my numbers hardly changed after doubling the levo dose.  My question is...

How sensitive are your labs typically to how closely you follow the medication instructions?  My instructions are to take it an hour before any food and four hours before any other meds (esp. calcium or iron).  I've been somewhat more lax about taking on an empty stomach more recently on the 50 than earlier, but not a WHOLE lot.  Sometimes I'm too hungry in the morning and I just take it with my other pills.  That was the only reason I could think of for the numbers not budging.  Any other thoughts on that or pursuing the next step more generally?

Thanks.

[RCinNY]

Interesting ideas, thanks.

I was last tested when taking vitamins for only B-12 and D (I've since switched to Men's 1-a-day).  B-12 was over the range and D was 39 (30-100).  Ferritin was 135 (20-345), although one of my other iron labs was a bit off (I posted in the "liver" section about that).

I experimented a little more w/ the levo. and not sure if I was imagining things but I felt a little jittery at night taking it too late.  I've been feeling much better lately (still not sure why), and I'm thinking to continue doing what I'm doing.

[Red_Star]

Excerpt from the article - Should You Take Your Thyroid Medication at Night?...

"In 2007, Clinical Endocrinology reported on a small pilot study, which looked at the impact on thyroid hormone profiles by changing the time levothyroxine was taken from early morning to bedtime. They also evaluated the impact of this change on the circadian rhythm of TSH and thyroid hormones and thyroid hormone metabolism. The study, while small (12 subjects), was fairly conclusive in its findings, which the researchers said were “striking” and which have “important consequences for the millions of patients who take l-thyroxine daily.”

Researchers reported that taking medication at bedtime, rather than the morning, results in “higher thyroid hormone concentrations and lower TSH concentrations.” TSH decreased and Free T4 levels rose in all patients by changing thyroxine ingestion from early morning to bedtime and T3 levels rose in all but one subject. And TSH decreased irrespective of the starting TSH levels, suggesting better absorption of the thyroid medication when taken in the evening. Interestingly, the researchers found that the circadian TSH rhythm -- the typical daily fluctuations of TSH that occur during a 24-hour period -- dids not vary.

The researchers suggested several explanations for the results:

Even when waiting at least 30 minutes to eat, breakfast may be interfering with the intestinal absorption of levothyroxine thyroxine.

“Bowel motility is slower at night,” which means that it takes longer for the levothyroxine tablet to transit through the intestinal system, resulting in longer exposure to the intestinal wall, and therefore, better uptake of the medication.

The conversion process of T4 to T3 may be more effective in the evening."

[gimel]

You have to remember that serum thyroid levels are the sum of both endogenous and exogenous sources of thyroid hormone.  As you raise your thyroid med, the TSH is reduced, and in response your endogenous, natural thyroid hormone production, is diminished.  It is not unusual at all for serum levels to show very little change until the TSH is reduced enough that it is no longer a factor and the entire amount of serum thyroid is due to exogenous sources  (thyroid med).  Frequently hypo patients taking significant doses of thyroid med find that their TSH becomes suppressed, which runs the risk that the doctor mistakenly thinks you have become hyperthyroid.  In reality you become hyper only if having hyper symptoms due to excessive levels of Free T3 and Free T4.  For example, my own TSH has been about .05 or less for well over 25 years, with no hype symptoms.  There are also scientific studies that confirm this.  

Now looking at your test results, it seems that your T4 med is raising your Free T4 adequately, but your body is not adequately converting the T4 to T3.  As a result your free T3 is way too low, at least for most hypo patients anyway.  /scientific studies have shown that Free T3 correlated best with hypo symptoms, while Free T4 and TSH did not correlate at all.  So I suggest that you really need to get your doctor to add a source of T3 to your meds and gradually adjust as necessary to relieve symptoms.  Symptom relief should be the main concern, not just test results and especially not TSH.  

In addition, hypo patients are frequently too low in the ranges for Vitamin D, B12 and ferritin.  If you have been tested for those please post results and their ranges shown on the lab report.