Posted by: Chris Maloney | January 21, 2013

Thyroid Function and Weight Loss: Get A Full Check Up.

Thyroid Scar

Thyroid Scar (Photo credit: grrrrr123)

These days the media is full of ads for “weight loss surgery” which make it sound like a walk in the park.  Which got me thinking about thyroid function and weight loss.

If you look at my website: under What Do I Treat and weight loss, you’ll see a clear thyroid connection.  The summary is that people trying to lose weight often lose thyroid function instead.

So shouldn’t someone be actively working to make sure the thyroids of obese patients are fully functional before we put them under the knife?  Well, that would be an endocrinologist‘s turf, not the area for a gastric surgeon.  So unless an obese person actively pursued a full check up, chances are pretty good we’d miss this particular step.

Even if a visit happened, chances are good that all the endocrinologist would do is a TSH, not realizing that TSH is often elevated in obese patients while the free, active hormone is decreased.  To paraphrase the experts:  the relationship between weight and thyroid is complex.

Which brings me to another thyroid function tip:  do not get your thyroid levels checked after your doctor palpates your thyroid.  Pushing on or rubbing the thyroid increases thyroid levels temporarily.  I remember first discovering this in the prostate studies, when older guys would get their prostates examined and then show up with elevated PSA levels.

A decent lab of your thyroid would include at least three numbers:  TSH (brain stimulating the thyroid), free T4 (free, inactive hormone) and free T3 (free, active hormone).  If you’ve seen the ads for testosterone, these are the kind of tests we’d do to justify putting you on the hormone.  So they are the same tests we need to do before we justify putting someone under the knife.

Finally, you should get a thyroid panel done because obesity can affect thyroid levels.  In obese children thyroid levels get elevated, but don’t lead to weight loss.  Weight loss leads to normalizing thyroid levels.  So it’s worth having your levels checked.

Here’s an abstract showing the minimum number of tests needed and a description of what happens with thyroid and obesity in children.  It’s complicated.

Horm Res Paediatr. 2010;73(3):193-7. doi: 10.1159/000284361. Epub 2010 Mar 3.

Thyroid function in obese children and adolescents.

Marras V, Casini MR, Pilia S, Carta D, Civolani P, Porcu M, Uccheddu AP, Loche S.


Servizio di Endocrinologia Pediatrica, Ospedale Regionale per le Microcitemie, Cagliari, Italy.



Obesity is frequently associated with modifications of thyroid size and function. We evaluated the prevalence of thyroid function abnormalities and the effects of puberty and weight loss in obese children and adolescents.


We examined 468 obese children (255 girls and 213 boys aged 3.7-17.9 years) and 52 normal-weight age-matched children as controls. TSH, fT3, fT4, fasting serum insulin and glucose were measured at baseline. fT3, fT4 and TSH were also measured after 6 months of lifestyle intervention in a subset of 43 patients.


109 obese children showed abnormal circulating thyroid hormone concentrations (84 had elevated fT3 levels, 15 elevated TSH, 6 elevated fT4, 3 elevated fT3 and TSH, and 1 elevated fT3, fT4 and TSH levels). Serum TSH and fT3 concentrations were positively correlated with BMI-SDS. The prevalence of patients with abnormal thyroid hormone concentrations was similar between sexes and between prepubertal and pubertal subjects. After 6 months of lifestyle intervention, thyroid hormone concentrations normalized in 27 of the patients with decreased BMI-SDS, and in 2 patients in whom BMI-SDS increased.


In obese children, an increased fT3 concentration is the most frequent thyroid function abnormality. Serum fT3 and TSH correlate with BMI. Moderate weight loss frequently restores these abnormalities.

Copyright 2010 S. Karger AG, Basel.



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