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Thyroid UK
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11 year old son with a possible underactive thyroid

My son had some blood tests recently to check if his thyroid is underactive (still waiting for the results). He does have quite a few symtoms which makes me think it is underactive (tiredness, irritability, very anxious etc.). If he's given medication for this will i see an immediate change? Is thyroid medication very effective?

Thank you

3 Replies

Hi there

Recovery time depends on how long he's been ill without treatment prior to diagnosis. It can take a year to a year and a half; with gradual improvements during that time.

They have to up the dose slowly at first (they will give him the first set dose, test his blood after 6 to 8 weeks and then increasE if necessary). While he's ramping up the dose in this way he may have days where he feels worse not better, especially in the first couple of weeks of a dose change.

You also need to get vitamin levels checked - others can advise on this better than me. Mainly it's foliate, ferritin and D; these need to be in the upper end of the range (not just in the normal range) to allow his body to metabolise the medication properly.

Sorry to be the bearer of bad news; thyroid is not a quick fix condition but the good news is that you do get better in the end and it is very treatable.

Good luck


My 11 year old girl just had one also. Have to ring up for the results today. Will be getting a print out as I suspect that they have only tested her tsh. She displays signs of being hyper. It takes a good 4 weeks for thyroid meds to kick in properly but he should start to feel better after a few weeks. Will be about a year as stated above before his levels are fully right. Good luck.


Once you have the results of his blood tests, please get a print-out with the ranges and post on a new question for responses.

A blood test for thyroid hormones should be the very earliest and it should be a fasting test although you can drink water. Eating can reduce the results and as doctors only take notice of the results and not the symptoms, one may remain undiagnosed. Also Vit B12, Vit D, iron, ferritin and folate should be checked as we can also be deficient, thus have problems too.


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