Synthroid seemed to drop my TSH very quickly - is this normal?

[ThyroidGuy745]

My TSH has always been high normal or a little high.  My last test was 5.1 (ref range 0.27 to 4.2)   Free T4 was 14.2 (ref range 10.5 to 20.)   Due to a strong family history, I've had a number of tests over the years.

Doctor suggested I give Synthroid a shot (50 mcg per day) as I may notice an improvement to my fatigue.    I was going on vacation so I got the Rx and then waited until I returned before starting.    Once I started taking the pills, I only lasted 4 or 5 days before having a lot of hyper symptoms (headaches, shaking.)   I got tested after only 5 or 6 days of taking the Synthroid and TSH was 1.59 (ref range 0.34 to 4.82)  Free T4 was 15.4 (ref 10-20) and Free T3 was 4.3 (ref 3.5 to 6.5)  

Does it seem surprising that a small dose of Synthroid would drop my TSH in only a few days?   I expected that it would take much longer.

Advice from the doctor is to not take it anymore and so I have stopped as of this morning.

[goolarra]

Results of antibody tests would be really interesting.  Looking back at your pre-meds labs, I question if you really are hypo.  FT4 is at 39% of range, which is a little low of the 50% target, but low enough to cause symptoms???  Besides fatigue, which symptoms do you have?

Are you a mathematician or an engineer?  The mathematician will tell you it will be 4-6 weeks before all the meds you took are completely out of your system.  The engineer will say that after taking them for only six days, a couple of weeks is close enough.  It takes the meds the same time to build as to purge.

After taking thyroid hormones for such a short period of time, I wouldn't expect any major swings after stopping.  

Synthroid has no permanent effects, so yes, your levels should return to pre-meds levels (assuming your thyroid is still producing the same amount, i.e. getting neither more hypo nor hyper for other reasons), and symptoms should resume.  Did any of your symptoms resolve in those six days?  

[ThyroidGuy745]

Thanks - I may have had those tests run in the past so I will see if they were already done.

Interesting about the way the body responds.  I feel that my body was going fairly hyper so I think it was a good decision to stop taking the Synthroid and get back to my normal baseline and then consider re-introducing it at a lower dose.   I was only six days in and having some pretty serious problems so it may have just got worse.

What do you think my body will do over the next few weeks?  I just plotted the cumulative half-life curves from taking six days of Synthroid.  It came up very quickly obviously but it will take weeks to drop down.  During that time will all my systems normalize to how they were before I took the Synthroid? (will the adrenals pick up the slack again?)   Or is there a chance that I will go through some swings (hypo or hyper,) on the way down or that they might not return to my previous normal?

[goolarra]

I asked how old you were because older people often have to start at a lower dose than younger people do.

It's not that you won't notice anything for 6-8 weeks; it's that it takes 4-6 weeks for the meds to reach their full potential in your blood.  In the meantime, levels are changing.  When we're hypo, other body systems tend to take over and try to compensate for lack of thyroid hormone.  For example, adrenals are infamous for this.  When you introduce exogenous hormones, your body has to rebalance.  Adrenals have to back off.  The T4 you are taking can lower your TSH enough to inhibit some endogenous thyroid production.  I wouldn't call this "wild swings", but it can cause you to feel a little worse before you feel better.  That's why starting at a lower dose and increasing as needed is often recommended, especially for older people.

A new baseline test isn't a bad idea.  Were the two sets of labs drawn at approximately the same time of day?  When you do, you might consider adding the antibody tests for Hashi's to FT3, FT4 and TSH.  These are TPOab (thyroid peroxidase antibodies) and TGab (thyroglobulin antibodies).  Hashi's is the most prevalent cause of hypo in the developed world and "runs in families".  So, if you have a strong family history, it's probably Hashi's.  Do you know if any of the rest of your family has it?  

Do you have other symptoms besides fatigue?  

[ThyroidGuy745]

I am 30-33.  FT3 not tested before meds.


I guess I feel like I am hearing two stories:

1) This is a fairly mundane "drug."  I probably won't even notice anything and over 6-8 weeks I will feel better.

vs

2) Your body may go into wild swings in the first few weeks.

I think I will take time off, get another baseline test and then maybe start at 25?

[goolarra]

The problem is that when you start thyroid meds, it sends your system into flux.  With the addition of exogenous hormones, everything has to rebalance.  So, a retest after just a few days is virtually useless.  

How old are you?

It might be that you should have started at a lower dose.

Was FT3 tested before starting meds?