Levothyroxine and Allupurinol interaction with TSH

[rick2525]

I have been on Levothyroxine for 2 years and the only other med I take daily is Allupurinol which I have done for 10 years. I have never thought to read the leaflet on side effects in belief that my GP would have checked for any side effects......how wrong was I ! Reading the leaflet last week one of the common side effects listed is that Allupurinol causes Increased level of TSH in the blood. When I asked the GP about this last Friday she said she was not aware of this until I brought it to attention. Bearing in mind the symtoms I have posted on this website before could this be the reason for them? Anyone else had this problem with this drug.?

[tattybogle]

i posted something about allopurinol a few days a go ..... i'll find it ...

[tattybogle in reply to tattybogle]

see last 4/5 replies at end of this post healthunlocked.com/thyroidu...

[rick2525 in reply to tattybogle]

Thanks for reply. When I mentioned this to GP she said she would contact the pharmacist for advice!! Didnt seem to be aware of interaction with levo until I mentioned it. My T3 is low not fully converting but of course the GP wont or dont measure this.She just said theres no alternative to Allupurinol. I have not had a gout attack in 10 years . But I only have one kidney on stage 3 which seems to have stabilised on functioning

I have a private appointment with Endo in August maybe he can advise.

[tattybogle in reply to rick2525]

I was having a look into allopurinol due to my Other Half currently having fun with recurrent gout. (probably largely sausage related , but he does have polycythemia too which can make it more likely) .It seems to be in the box of "we've noticed it can do something to thyroid levels but we aren't sure exactly what or how ". some studies seem to disagree about 'what'.. some say TSH is affected and fT4 isn't , while some say Total T4 isn't affected but Free T4 is.

Just noticed this quite recent one : nature.com/articles/s41598-...

"Published: 13 October 2021

Association between the use of allopurinol and risk of increased thyroid-stimulating hormone level"

This one suggests significant rise in TSH levels , (ie previous 2 ish rising to 10 ish ) with much less effect on fT4 levels.( a small drop)

It doesn't draw any conclusions about autoimmunity ,because they didn't have access to any data on the subjects antibody levels .

[tattybogle in reply to tattybogle]

japer.in/storage/models/art...

Journal of Advanced Pharmacy Education & Research | Oct-Dec 2020 | Vol 10 | Issue 4

" Effect of chronic Allopurinol therapy on Thyroid function in patients with urate stones "

"ABSTRACT

A xanthine-oxidoreductase enzyme is responsible for purine metabolism in our body; converting purine to its end product in the form of uric acid. Inhibition of this enzyme will then reduce uric acid in gout patients, however, it could have some side effects on other tissues and organs. The present study aims to identify the effect of long-term use of allopurinol in modulating the thyroid function in a patient with urate-type renal stone. The result revealed that allopurinol reduced the levels of free form of thyroid hormone and elevate TSH level with no effect reported with the bound thyroid hormones; these results were confirmed by ultrasonography results

obtained for the patient before and after allopurinol therapy showing enlarged thyroid gland, change in echogenicity, and increased blood supply with nodule formation in few of them. These study has concluded that allopurinol could induce a state of subclinical hypothyroidism. "

[suza1216 in reply to rick2525]

Late reply sorry only just seen your tread. Febuxostat is an alternative to allopurinol for those who find allopurinol ineffective at controling their uric acid levels or who cannot tolerate side effects. Of course it is more expensive than allopurinol and many GPs dont seem to know about it or pretend they don't.

[tattybogle in reply to suza1216]

i'm fairly sure i saw ?febuxostat mentioned in one of those studies as also showing these effects on TSH / fT4 etc .

[SlowDragon Administrator]

Being hypothyroid can increase likelihood of gout

amjmed.com/article/0002-934...

[helvella Administrator Thyroid UK]

Not in any way meant to criticise you, but this is why I so often encourage members to read the Patient Information Leaflets. And my medicines document also links to the Summary of Product Characteristics documents which are often more comprehensive.

They get updated quite frequently. If you are on several medicines, especially if manufacturers also change, you can have a lot of reading to do!

Should you have to do this? No.

On the one hand, we cannot expect every GP to know every interaction. But nor can we expect every patient to read every PIL and SPC document. And pharmacists, who we are often told to talk with, often don't know everything we are taking either.