Patients treated for hyperthyroidism are at increased risk of becoming obese: findings from a large prospective secondary care cohort

[helvella]

Please do read even if your background and interests are hypothyroidism.

Thyroid. 2019 Aug 2. doi: 10.1089/thy.2018.0731. [Epub ahead of print]

Patients treated for hyperthyroidism are at increased risk of becoming obese: findings from a large prospective secondary care cohort.

Torlinska B1, Nichols L2,3, Mohammed MA4, McCabe C5, Boelaert K6,7.

Author information

1 University of Birmingham, Institute of Applied Health, Occupational Health Building, Edgbaston, Birmingham, Birmingham, West Midlands, United Kingdom of Great Britain and Northern Ireland, B15 2TH; [e-mail].

2 University of Birmingham, Institute of Applied Health Research, Birmingham, United Kingdom of Great Britain and Northern Ireland.

3 University of Warwick, Department of Statistics, Coventry, United Kingdom of Great Britain and Northern Ireland; [e-mail].

4 University of Bradford, 1905, Faculty of Health Sciences, Bradford, West Yorkshire, United Kingdom of Great Britain and Northern Ireland; [e-mail].

5 University of Birmingham, Institute of Metabolism and Systems Research, Birmingham, United Kingdom of Great Britain and Northern Ireland; [e-mail].

6 University of Birmingham, Institute of Metabolism and Systems Research, Birmingham, United Kingdom of Great Britain and Northern Ireland.

7 Birmingham Health Partners, Centre for Endocrinology, Diabetes and Metabolism, Birmingham, United States; [e-mail].

Abstract

BACKGROUND:

The most commonly reported symptom of hyperthyroidism is weight loss; successful treatment increases weight. Weight gain faced by patients with hyperthyroidism is widely considered as a simple re-accumulation of premorbid weight, whereas many patients feel there is a significant weight "overshoot" attributable to the treatment. We aimed to establish if weight gain seen following treatment for hyperthyroidism represents replenishment of premorbid weight or "overshoot" beyond expected regain and, if there is excessive weight gain, whether this is associated with the applied treatment modality.

METHODS:

We calculated the risk of becoming obese (BMI>30 kg/m2) following treatment for hyperthyroidism by comparing body mass index (BMI) of 1373 patients with overt hyperthyroidism seen in a secondary care setting with the age- and sex-matched background population (Health Survey for England (2007-2009)). Next, we investigated the effect of treatment with antithyroid drug alone in regard to antithyroid drug with radioiodine therapy. We modelled the longitudinal weight data in relation to the treatment pathway to thyroid function and the need for long-term thyroxine replacement.

RESULTS:

During treatment of hyperthyroidism, men gained 8.0 kg (SD±7.5) and women 5.5 kg (±6.8). At discharge, there was a significantly increased risk of obesity in male (OR=1.7, 95%CI 1.3¬-2.2, P<0.001) and female (1.3, 1.2-1.5, P<0.001) patients with hyperthyroidism compared with the background population. Treatment with radioiodine was associated with additional weight gain (0.6 kg, 0.4-0.8, P<0.001), compared with antithyroid drug treatment alone. More weight gain was seen if serum TSH was markedly increased (TSH>10 mIU/L; 0.5 kg, 0.3-0.7, P<0.001) or free thyroxine was reduced (fT4 ≤10 pmol/L (0.8 ng/dl); 0.3 kg, 0.1-0.4, P<0.001) during follow-up. Initiation of levothyroxine was associated with further weight gain (0.4 kg, 0.2-0.6, P<0.001) and the predicted excess weight gain in radioiodine-induced hypothyroidism was 1.8 kg.

CONCLUSIONS:

Treatment for hyperthyroidism is associated with significant risks of becoming obese. Radioiodine treatment and subsequent development of hypothyroidism were associated with small but significant amounts of excess weight gain compared with antithyroid drugs alone. We advocate that the discussion over the weight "overshoot" risk forms part of the individualised treatment decision making process.

PMID: 31375059

DOI: 10.1089/thy.2018.0731

ncbi.nlm.nih.gov/pubmed/313...

[FarmerDJ]

Great, now we've got obesity to contend with too. As if we didn't have enough problems 😂

[bantam12 in reply to FarmerDJ]

I haven't put any weight on, been on Carb several times and had RAI 🤷‍♀️

[Gingernut44 in reply to bantam12]

Lucky you, are you now on Levo?

[bantam12 in reply to Gingernut44]

Yep for getting on 20 years 🙂

[Calends in reply to FarmerDJ]

Right!!!!!!!! When they put me on Levothyroxine in March I gained 1 pound a week for 11 weeks! I finally told my Doctor I was going to hurt her. Seriously, how wrong is all this?

[Jeandon in reply to Calends]

What did your doctor do ? I was diagnosed 8 years ago after gaining 4 stones. I take 100mcg thyroxine and my weight is still the same it never goes up or down, I do three exercise classes a week, doctor sent me to slimming world, didn’t do anything I don’t eat a great diet I’m very fussy but I try and eat healthily. I get really depressed about this because I speak to my gp and they won’t do anything. I had breast cancer 21 years ago I weighed 7 stones chemo put my weight up to 10 stones then I lost a stone got stuck there , because chemo gave me arthritis now I’ve had two knee replacements and been exercising since but I still weigh 13 stones. I get really fed up.

[Calends in reply to Jeandon]

Frustrating to the nth degree. To answer your question: she told me a story about a guy who had gained 100 pounds in a year! This did not make me feel better. She said it doesn't matter what you eat because it has nothing to do with what goes in. She did say that exercise is always important because now that you have gained so much weight you'll want to keep up with your cardio! She did change me off of generic Levo and put me on Synthroid at a lower dose but I am back up to 75.

It is without a doubt the most frustrating situation I have ever found myself in.

Take care and keep talking. At least we have each other.

[humanbean]

Surely one reason for this is glaringly obvious.

People who have suffered from hyperthyroidism will have a very low TSH. Treating the hyperthyroidism doesn't necessarily return TSH to whatever would have been normal for that person before they became ill.

If or when the hyperthyroid person becomes hypothyroid, as so many of them do, the non-response of their TSH to low thyroid hormone levels will be taken as evidence of over-treatment by doctors and replacement thyroid hormones will be kept too low.

Since under-treated hypothyroidism is known to increase the risk of obesity, then people who have been hyperthyroid in the past will struggle with the same risks.

[helvella Administrator Thyroid UK in reply to humanbean]

The other glaringly obvious factor is that destroying the thyroid by RAI removes (or considerably reduces) its part in maintaining T3 levels. Whereas, with anti-thyroid medicines, there is the potential for it to return to taking its full role.

[thyroidnodules in reply to helvella]

this is very interesting, as when i gained weight after having my thyroid treated with RAI and eventually being put on levo, i put on even more weight. doctors dont believe you when you tell them the levo is making you put on more weight - at least now i know it is not in my imagination lol. since switched to Thiroyd, i have lost over a stone and can eat normally. thank heaven for this forum as i would probably be very obese by now and totally skint with trying every diet under the sun

[Gingernut44 in reply to humanbean]

My situation exactly - my Doctor has kept me under medicated for the past six months since RAI and becoming hypo and the weight is still going on and I still feel cr*p ☹️

[Greekchick]

Thanks for posting this, helvella. And there is another reason not covered in the paper - when you are hyper your appetite increases to the point that you want to eat everything in sight. Two months before before my surgery, I gained 10 pounds in 3 weeks - I managed to lose it all before surgery because for health reasons I was terrified of gaining even more weight after the TT - but it is a problem: not everyone loses weight when they are hyper. It is a common misconception.

[helvella Administrator Thyroid UK in reply to Greekchick]

I have long been aware of what you say - and that with both hypothyroidism and hyperthyroidism, weight can go up or down. All too many who should know better fail to appreciate that.

[annnsandell]

Interesting. Does anyone think this is because most people are not on enough T4 or T4/T3 to compensate or is it just that these Thyroid drubs are not doing everything that they need to? Would have been good if this research went further.

[Valarian in reply to annnsandell]

I don’t think they know - and it could be a mix of things. My endo did say that initial big weight loss (usually before diagnosis) followed by a period of weight maintenance and then a steady gain (even before RAI/TT) is quite a typical Graves’ profile. It seems to be one of the many things thyroid-related that needs more research !

[Blethering19]

At least they have confirmed that this can happen. I have put on nearly two stone while they faff about with the correct dose of Carbimazole. To be honest I would rather go back to the effects of hyperthyroidism than go through the rest of my life as a blob. Whoever said you would kill for your next mouthful wasn’t joking. So, what is the solution please? Once the meds are honed can you go back to being a normal size or is this it now. Would genuinely like to know.

[SilverAvocado in reply to Blethering19]

My observation on the forum is that you can either be a lucky one, or be an unlucky one.

Quite a lot of lucky people will lose the weight without even trying once they get on optimal thyroid replacement. But then for another group of people the weight sticks around even once all their other symptoms are largely gone.

[Valarian in reply to Blethering19]

My endo suggested that part of the gain could be down to the body thinking you are trying to starve it during the weight loss phase, and therefore doing its best to hang onto any spare calories. Getting into the habit of eating everything in sight without putting on an ounce of weight obviously doesn’t help. Exercise levels probably reduce too.

I have put on weight, and am now managing to lose it. I’m pretty much euthyroid, but still on 15mg/day of carbimazole. My aim is to lose as much as possible over the next few months in case I need to consider RAI/TT.

[NWA6]

My sister dealt with her Hyper symtoms by training for an Ironman. She was always very slim at a size 8, she probably went down to a 6. She was on and off Carb for 5yrs, refused any other treatment even with a goitre. Now she’s a size 16/18 with a very puffy face. She won’t listen to me to get a full Thyriod check ( I’m the younger sister she’s head of the physio dept and believes her Endo colleges know what their talking about) I’ve gotta let this one go and let her do what she wants even if I know she’d feel better if she were medicated 😩

[SilverAvocado]

I bet there are a lot of people on the forum who WISH it was only 5.5 kg!

[Aurealis]

Haven’t had time to read article yet, but is it because they’ve adjusted using TSH and we’re all undertreated 😂🤣 not at all funny I know !