Thyroid UK
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Blood test results with 75 mcg SYNTHROID for 6 weeks: do I need T3?

Hello. These are my results after 6 weeks taking 75 mcg of SYNTHROID. The before results are with no thyroid medication. I am male, 38 years old, 72 kg:


Before: 5,09 uUI/ml

After: 1,13 uUI/ml

Ref: 0,40 – 4,30

Free T4:

Before: 1,01 ng/dl 28,18 % in the range

After: 1,18 ng/dl 43,63 % in the range

Ref: 0,70 – 1,80 ng/dl

Free T3:

Before: 0,34 ng/dl 70% in the range

After: 0,32 ng/dl 60 % in the range

Ref: 0,20 – 0,40


Before: 264 mg/dl

After: 247 mg/dl


Before: 72 mg/dl

After: 59 mg/dl


Before: 158 mg/dl

After: 141 mg/dl


Before: 62 mg/dl

After: 36 mg/dl

So, whit 75 mcg of SYNTHROID, my TSH dropped a lot; my FreeT4 increased as expected, but my FreeT3 dropped, indicating a conversion problem and the need for T3??

Strange that my cholesterol doesn’t decreased as expected, and my triglycerides dropped a lot, I don’t know what this indicate.

Yesterday I tried 1 grain of NDT to my 75 mcg T4 dose. I divided the 1 grain in four parts and take it 4 times a day, and fells worse, more tired and depressed!!

Also, in this 6 weeks, my temperatures stayed the same: 35.9 Celsius at wake up, so the T4 did nothing for my low temperature.

The only improvement I see is that I fell more relaxed along the day, but the constipation, fatigue and pain on the joints of my legs persists.

So, what should I do:

1. Increase my dose to 100 mcg T4?

2. Ad T3, but How? It looks that I feel worse whit it.

Thank you very much for any help.

4 Replies


Prior to taking Synthroid FT3 was high due to your high TSH stimulating conversion. Now that TSH has dropped so has FT3.

Your TSH is low but FT4 and FT3 could be higher so I would increase dose to 100mcg. Don't worry about temperature. Some people have a naturally low temperature but even if it was caused by hypothyroidism it will take a lot longer than six weeks to recover.

It's also worth asking your GP to check ferritin, vitamin D, B12 and folate. They're commonly low or deficient in hypothyroid patients which may cause fatigue, musculoskeletal pain and low mood similar to hypothyroid symptoms.

You took too much NDT. 1 grain is equivalent to 65mcg so you more or less doubled your dose.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.

1 like


Thank you very much. I will increase it to 100 mcg and retest in 6 weeks.

My outher results are:

Vit. D3: 77,9 ng/ml Ref: 30 – 100

Ferritin: 230 ng/ml Ref: 22 – 322

B12: 1789 pg/ml Ref: 211 – 911

Folic Acid: 21,3 ng/ml Ref: > 5,38 ng/ml

I don’t know if this folate level is ok. My b12 is high because I take 1.000 mcg of hydroxocobalamin. I take too 5.000 iu of Vit. D3.



Vitamin D is optimal around 50ng/ml. You might consider reducing D3 dose to 5,000iu alternate days.

Ferritin, B12 and folate levels are good.


Ok, I will do that, Thank you very much.


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