TSH from 0.03 to 5 without Meds?

[slore]

In March my doctor ran some generic blood work on a regular work-up.  My TSH came back with a reading of 0.03.  She sent me back for repeat blood work in case of lab error and to check my T3 and T4 and referred me to an endo. Those results came back a week later:
TSH 0.04
T4 13
T3 4.7

The endo thought it could be some  subclinical hyperthyroidism, she didn't want to treat me with any medication because my T4 and T3 were normal.  But she sent me away with a requisition to redo my blood work in 3 months.  I went this week and my results came back:
TSH 4.98
T4 12
T3 5.4

Why? My T4 and T3 seem so consistent with the previous blood work but is it normal for my TSH to go from being SO low to being high in less than a 3 month span?  Has anyone else experienced this?

Thanks!

[goolarra]

You can see that, despite the huge change in TSH, your FT4 hasn't changed a lot.  However, FT3 actually changed significantly.  It went from 40% of range to 63% of range.  FT3 is the test that correlates best with symptoms.    

Once again, do you have symptoms, and if so, did they change between these two sets of labs?

[goolarra]

TSH is very volatile and can change as much as 70% just depending on what time of day the blood was drawn.  It's also a pituitary hormone and a very indirect measure of thyroid status.  FT3 and FT4 are much more important.

What are the reference ranges on your T3 and T4?  Ranges vary lab to lab and have to come from your own lab report.  Also, do they say they are FREE T3 and FREE T4?

Do you have any symptoms?  

[slore]

Thanks for the reply, they T4 and T4 tested were FREE.

Results with ranges as directly from my labs,
March-
TSH 0.04 (0.30- 4.00)
Free T4 13 (9-23)
Free T3 4.7 (3.5-6.5)

June-
TSH 4.98 (0.30- 4.00)
Free T4 12 (9-23)
Free T3 5.4 (3.5-6.5)