Overweight Children Face Higher Risk of Thyroid Damage
Children who are overweight or obese may be damaging their thyroid glands, a problem that could contribute to or worsen their weight problems, according to Italian researchers. It's thought that obesity may trigger inflammation, which in turn is damaging the thyroid, according to the study reported in the Journal of Clinical Endocrinology and Metabolism's December 2008 issue. The study looked at 186 overweight and obese children, over a period of more than three years. In all the children, free T3, free T4, thyroid stimulating hormone (TSH), and antithyroid antibodies were measured, and a thyroid ultrasound was performed. (Forty healthy and normal-weight children matched for age were the study's controls.)
The results:
- 23 children (12.4%) showed antithyroid antibodies and an ultrasound pattern suggestive of Hashimoto's thyroiditis (group A)
- 20 children (10.8%) showed normal ultrasound together with antithyroid antibodies (group B)
- 70 children (37.6%) showed an ultrasound pattern suggestive of Hashimoto's thyroiditis but with no antithyroid antibodies (group C)
- 73 children (39.2%) showed a normal ultrasound and no antithyroid antibodies (group D)
It's more understandable in the case of the children who have a more clear cut case of Hashimoto's thyroiditis (group A), or who appear to have the antibodies suggestive of the thyroid disease, and likely have a milder form of thyroiditis (group B).
The children in Group C, however -- who did not have autoimmune thyroiditis -- tended to have higher TSH levels that fell above the upper limit of the normal reference range, and had ultrasound images that looked like autoimmune thyroiditis, even if antibody tests were negative. (A small percentage of patients with Hashimoto's thyroiditis do not show circulating antibodies, so the researchers also did cell studies -- which can definitively rule out Hashimoto's disease. They confirmed that this group did not have Hashimoto's thyroiditis.)
The researchers concluded that the connection between body mass index and the thyroid results suggest that being overweight or obese may actually be involved in the mechanisms that cause the thyroid dysfunction in the first place.
Also, because the frequency of Hashimoto's thyroiditis was far higher in the group of obese patients, versus the 1.2% rate other studies have found in children of normal weight, the researchers also speculated that fat excess may have a role in changing the thyroid tissue itself.
In an Endocrine Society statement, Giorgio Radetti, MD, lead author of the study, had this to say:
Our study shows that alterations in thyroid function and structure are common in obese children and we may have uncovered the link," said "We found an association between body mass index and thyroid hormone levels which suggests that fat excess may have a role in thyroid tissue modification."The researchers indicated that since thyroid function has been reported to return to normal after weight loss by a number of studies, this new research brings up the question of whether the ultrasound changes to the thyroid that were observed may be reversible. The study also raises the question of whether untreated or persistent thyroid abnormalities in obese children may progress into chronic thyroid disease in adulthood.
The researchers concluded with a caution that Hashimoto's thyroiditis in obese children not be diagnosed only on the basis of an ultrasound, but also require evidence of antithyroid antibodies.
NOTE FROM MARY SHOMON
I'm not sure about the researchers' conclusion that visible thyroid changes -- i.e., abnormal ultrasound results -- without thyroid antibodies should not be treated. If the children are overweight/obese, show evidence of thyroid abnormalities according to ultrasound, and have high-normal TSH levels, why wouldn't doctors consider a trial of thyroid hormone to see if it helps restore levels to normal and help the child with efforts to achieve a healthier weight? I realize that we don't want to be throwing thyroid medication at half the population, but why does it seem that the researchers go out of their way to exclude people from thyroid treatment? It's the same issue we keep coming up against with subclinical thyroid disease. The risks of treating it are small, and yet despite study after study showing increased health risks associated with having subclinical thyroid problems, many doctors still don't believe in treating it! Definitely areas that need more study.
SOURCES:
Radetti, Giorgio et. al. "Thyroid Function and Structure Are Affected in Childhood Obesity," The Journal of Clinical Endocrinology & Metabolism Vol. 93, No. 12 4749-4754 Online
Endocrine Society, Pediatric Obesity May Alter Thyroid Function and Structure
Photo: istockphoto
Comments
It seems to me that the thyroid damage is the cause of the obesity, not the other way around. If it is caused by the food fed to the children then look to see what additives could be damaging the childrens health.
I fully agree with both Mary and Janet. Additionally I wonder what reference limit for TPO-antibodies was applied in this study, because there doesn`t seem to be consent about what means “positive” in children. I had both of my daughters tested 3 years ago – different labs-different lower limits -no age relation. One was “negative” with 37, 3 month later she showed a positive ultrasound.
I agree also. They are putting the cart before the horse in assuming that current diagnostic methods and treatments work. In fact, they may not detect anything until the disease is advanced, and in the intervening years, the person has been coping with effects of thyroid disease. Symptoms — no matter how profound — seem to be ignored by the medical community if the TSH and antibodies are “OK”.
My own and my sister’s experience with Hashimoto’s backs this up. When we were small children, our wise doctor commented to my mother, “Watch these girls for thyroid disease.” (It was already in the family.) Even so, the antibodies indicative of Hashimoto’s didn’t show up until I was in my 40s, and my TSH was still “normal” for several years after that — yet I have been affected all my life by this horrible disease. I had my thyroid removed almost a year ago and my life has completely changed. My sister also had hers removed with the same positive results 6 months ago. We both wish we could have done it years ago.
The REAL clinical bug-a-boo seems to be that Hashimoto’s may often be a significant problem long before current methods can detect it or current treatments can do anything about it in advance if the TSH and antibodies are “OK”. Thyroid medical detection and treatment methods are primitive, at best.
I also wonder why the researchers didn’t think the weight problems were the RESULT of the thyroid dysfunction, not the cause. My son, who had always been a normal weight and very active athletic boy, suddenly starting gaining weight and having trouble getting out of bed in the morning around age 10. Because I and two of my sisters and my niece all have Hashimotos, I asked his doctor to test his antibodies — they were sky-high! He’s been on medication ever since (5 years) with very positive results. In my own case, symptoms preceded diagnosis by several years.
It’s extremely strange, like you have already written, that the researchers drew the conclusion that fat was the cause rather than consequence of hypothyroidism…
Aren’t they supposed to be clever?
I too think this is absurd. I believe with all my heart that the thyroid problem is the cause of the weight problem, not the the other way around. I have been hypothyroid since I was a child. My daughter was finally diagnosed with hypothyroidism after almost 6 years from when her symptoms first started. Her TSH was always in the higher “normal” range, so countless endos and doctors didn’t want to treat her. About a year ago she tested positive for the antibodies and they still didn’t want to treat her. I finally found a new doctor a couple of months ago that will listen! This poor child has continued to put on weight at an alarming rate starting at 3 years old. She has always been very active and I have always been diligent about my kids nutrition. Hopefully, her weight will stablize now that she has been on the Synthroid for about 6 weeks. She’s already noticed a difference in her ability to concentrate. I just want to say thanks to Mary for all the great information on thyroid issues! It has definitely helped me continue on my quest for good health for my daughter and myself.