Blood test results

[toise]

Hello,

As indicated by my recent blood test, my T3, T4 and free thyroxine are all within the normal range, but my TSH is high. What does this indicate?

Thanks,
Anna

[GravesLady]

How high TSH is high?

Its either subclinical or overt hypothyroid.

[toise]

TSH is 25.456.
What does 'subclinical hypothyroid' and 'overt hypothyroid' mean?

[GravesLady]

Subclinical is TSH up 10 with normal F/Ts with little symptoms. Or 5 to 10 with goiter or antibodies.

Overt is TSH higher than 10 with with normal or low F/Ts and lots of symptoms.

You look overt.  

Are you going to be treated?

[kitty9309]

Subclinical hypothyroidism is when the TSH is high, but free T4/T3 is in the normal range.
Overt hypothyoidism is when the TSH is high and the free T4 or T4 is low.
Severity of symptoms is not necessarily related to the TSH level.
Your results show subclinical hypothyroidism which is now beginning to be called "mild hypothyoidism" because there are often subtle symptoms.

[GravesLady]

toise correct me if I am wrong, you did say a TSH of 25.456?

Some doctors will consider high TSH with normal FTs as being overt and justifies treatment because eventually the FTs will go low.  

"subclinical" hypothyroidism is rather a vague term, it should be better called "minimal thyroid failure" and defined by laboratory rather than unprecise clinical criteria.
Moderately high serum TSH, say up to 10 mU/l, considering very high TSH values as denoting overt hypothyroidism, even if serum fT4 and fT3 are normal." Merck KGaA thyrolink 02.2005

Sorry about the confusion.

[kitty9309]

My definition is correct based on the reference from the AAFP online. Type subclinical hypothyroidism in as a search and you will see the definition.

[GravesLady]

"In short, it seems reasonable to treat patients who have a TSH level that is consistently elevated above 10 µU per mL (10 mU per L), especially if titers of antithyroid antibodies are increased. Also, patients who complain of fatigue, dry skin, constipation, muscle cramps or other common symptoms of hypothyroidism may possibly benefit from treatment even if their TSH level is elevated only into the 5 to 10 µU per mL (5 to 10 mU per L) range" AAFP American Family Physicians February 15, 1998

[kitty9309]

Are you being treated yet? I hope so. Do you have symptoms?
By giving you the definition of the above, I didn't suggest that it shouldn't be treated- of course you should be! Those are just the technical definitions of subclinical/overt hypothyroidism.

Hope you begin to feel better soon.

[toise]

Thank you both for the information, it is very helpful. I will talk with my doctor the next time I see him. Does anyone have a clue as to what causes the thyroid gland to gradually fail?

[toise]

Actually, I don't have any symptoms except for low tolerance to the cold, and I have had that for many years, way before my TSH began to elevate.

[kitty9309]

With a TSH as high as yours, they will more than likely recommend treatment. The most common cause of hypothyroidism is Hashimoto's thyroiditis. It is an autoimmune disease that causes your body to attack the thyroid and reduces it's ability to function as well as it should.