TSH goes lower w/ every Synthroid Drop

[jrcaleb]

Dr. Lupo, thank you for your time,

I've posted here before after expiencing bouts of what felt like hyperthyroidism - anxiety, sinus tachy, insomina, weight loss (more than 10lbs), blood pressure spikes, etc.  These symtpoms have been on and off since last November (07).  Since then my synthyroid dosage has been dropped from 137mcg/day to 100mcg (5 times a week).  I still can not put back on the weight and recently began experiencing the racing heart (usually in the morning) - worse when climbing the stairs to work.  It's not as bad as it has been before the drop in synthroid but still bad enough to take beta blockers from time to time.

TSH 0.8 in Nov '07 - No T4 test - 137mcg/day - Horrible Hyper symptoms - ER visit - Weight 164lbs.
TSH 0.4 in Jan '08 - No T4 test - 125mcg/day - Extremely horrible Hyper symptoms - ER visit - Weight 152.5lbs.
TSH 2.0 in Feb '08 - Free T4 1.8 Reference range is 0.8 - 1.8 - 100mcg/day - Felt better (occasional hyper feeling) - Weight 147lbs.
TSH 4.6 in Mar '08 - Free T4 1.5 100mcg 5x's/week - Felt better (some hypo symptoms). - Weight 149lbs.
TSH 1.9 in Apl  '08 - Free T4 1.4 100mcg 5x's/week - Felt real good - no symptoms. - Weight 151lbs.
TSH 2.2 in May '08 - Free T4 1.7 100mcg 5x's/week - Hyper symptoms/exercise intolerence- Weight 148lbs.

I have taken every test the doc could throw at me.  I've had a MRI and CT of head, thyroid panels, FNA of nodule in thyroid, EKG, ECG, Stress test, ENT eval, GI ultrasound of abdomen (awaiting results), CBC, 2 urine tests & 1 blood test for pheocromocytoma, AM cortisol test, H.Pylori, Celiacs, Pancreatic enzymes, etc.  Everything has come back normal.

I guess my question is, what can cause my synthroid dosage to drop like this?  It seems like something is speeding up my metaboilsm - worries me that cancer somewhere in my body may be doing this.  Any advice on possible things to check or look into would be greatly appreciated.  

Thank you,
Jon (27 y/o male)

[jrcaleb]

Dr. Lupo,

Thank you for your reply.  I forgot to mention that I stopped taking synthroid for a week and then for the past week and a half I have been taking 50mcg/day (my personal choice, not my endo's), and the hyper symptoms seem to be creeping back up.  It's been about three weeks since my last TSH/FT4.  I will mention your advice to my endo (will make an appt to get in sooner than next month).  Again, Thank you for your help.

[Mark Lupo, M.D.]

May be that your TSH is best between 2.5-5 range -- not uncommon.  Would give it more time with the current dose or decrease it a bit more - but then consider the possibility as well that the nodule is producing thyroid hormone.  Your dose is essentially 1/2 what it used to be which brings up the possibility of the thyroid making extra hormone.  An I-123 scan/uptake (on the current med....yes, ok to do on the current med, despite what the nuc med people will say) will prove if there is functioning thyroid tissue.