Subclinical hypothyroidism in obese children

Abstract

Objective: Thyroid functions in obese children and ado­lescents were evaluated in order to determine subclinical and clinical hypothyroidism. Materials and methods: In this study, 85 obese (Body mass index >97th percentile) children, aged 2-14 years, as well as 47 healthy controls were enrolled. Levels of serum free triiodothyronine (fT3), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) of the two groups were compared. Obese children with TSH level above 5.4 IU/ml were also analyzed for anti-thyroglobulin (anti Tg) and antiperoxidase antibodies (anti TPO) and thyroid ul­trasounds were performed. Results: Obese children showed higher serum concen­trations of TSH and fT3 than the controls but no significant difference in serum fT4 levels was found between the two groups (P=0.001). One child had high auto antibodies and 32 had high TSH levels. Of the latter, 29 children had normal thyroid ultrasound findings and three had nodules or thyroiditis but no enlargement of the thyroid gland. Conclusion: TSH and fT3 levels were found to be higher in obese children compared with non-obese children with no difference of fT4 levels between two groups.

Keywords

• Body mass index, obesity, thyroid functions

Obez çocuklarda subklinik hipotiroidi

Abstract

Amaç: Çocukluk çağı obezitesinde tiroid fonksiyonlarının değerlendirilmesi, subklinik-klinik hipotiroidinin saptan­ması amaçlanmıştır. Gereç ve yöntem: Çalışmamızda, 2-18 yaş arasında 85 obez, 47 obez olmayan hastanın, serbest triiyodotironin( sT3) ve tiroksin (sT4) ve tiroid stimülan hormon (TSH) dü­zeylerine bakıldı. Obez grupta, TSH düzeyi 5,4uIU/ml\'nin üzerinde saptanan hastaların, tiroid otoantikor düzeyleri ölçüldü ve tiroid ultrasonu yapılarak tiroid volümü hesap­landı. Bulgular: Obez hastaların sT3 ortalamaları ve TSH de­ğerleri, kontrol grubunun değerlerinde istatistiksel olarak anlamlı derecede yüksek bulunurken, sT4 ortalamala­rında iki grup arasında fark saptanmadı. TSH >5,4 IU/ ml olan hastalardan birinde otoantikor düzeylerinde yük­seklik saptandı. TSH >5,4 IU/ml olan 28 hastadan 25\'inin tiroid ultrasonu normal iken, kalan 3 hastada tiroidit veya nodül saptandı ancak tiroid büyümesi yoktu. Sonuç: Vücut kitle indeksi (BMI) yüksek hastalarda sT3 ve TSH düzeyi yüksek, sT4 ise normal saptanmıştır. TSH ve sT3 yüksekliği obesitenin bir sonucudur ve edinsel hi­potroidi ile ayırıcı tanısı yapılmalıdır.

Keywords

• Beden kitle indeksi, obezite, tiroid fonksiyonları

References

1. Ibanez L, Vals C, Ferrer A, et al. Sensitization to insulin induc- es ovulation in nonobese adolescents with anovulatory hy- perandrogenism. J Clin Endocrinol Metab 2001;86:3595-8.
2. Mutlu RGY, Özsu E, Çizmecioğlu FM, Hatun Ş. Elevated TSH levels in obese children: What kind of problem is it? Turk Arc Ped 2011;46:33-6.
3. Bundak R, Furman A, Gunoz H, Darendeliler F, Bas F, Neyzi O. Body mass index references for Turkish children. Acta Paediatr 2006; 95:194-8.
4. Taş F, Bulut S, Eğilmez H, Oztoprak I, Ergür AT, Candan F. Normal thyroid volume by ultrasonography in healty chil- dren. Ann Trop Paediatr 2002;22:375-9.
5. Rajala MW, Scherer PE. Mini review: The Adiposite at the crossroads of energy homeostasis, inflammation and ath- erosclerosis. Endocrinology 2003;144:3765-73.
6. Rondinone CM. Adiposite-derived hormones,cytokines and mediators. Endocrine 2006;29:81-90.
7. Sorisky A, Bell A, Gagnon A. TSH receptor in adipose cells. Horm Metab Res 2000;32:468-74.
8. Bell A, Gagnon A, Grunder L,Parikh SJ, Smith TJ, Sorisky A. Functional TSH receptor in human abdominal preadi- posites and orbital fibroblasts. Am J Physiol Cell Physiol 2000;279:335-40.

9. Stichel H, L’Allemand D, Grüters A. Thyroid function and obesity in children and adolescents. Horm Res 2000;54:14- 9.
10. Reinehr T, Andler W. Hyperthyrotropinemianin obese chil- dren is reversable after weight loss and is not related to lip- ids. J Clin Endoc Metab 2006;91:3088-91.
11. Reinehr T, Andler W. Thyroid hormones before and after weight loss in obesity. Arc Dis Child 2002;87:320-3.
12. Bhowmick SK, Dasari G, Levens KL, Rettig KR. The prevelance of elevated serum thyroid-stimulating hormone in childhood/adolescent obesity and autoimmune thyroid diseases in a subgroup. J Natl Med Assoc 2007;99:773-6.
13. Knudsen N, Lauberg P, Lone B, et al. Small differences in thyroid function may be important for body mass index and the occurrence of obesity in the population. J Clin Endocri- nol Metabol 2005;90:4019-24.
14. Lima N, Cavaliere H, Medeiros-Neto G. A retrospective study of thyroid autoimmunity and hypothyroidism in a random obese population. Med Sci Res 1987;15:31-2.
15. Bastemir M, Akin F, Alkis E, Kaptanoğlu B. Obesity is as- sociated with increased serum TSH level independent of thyroid function. Swiss Med Wkly 2007;137:431-4.
16. Karakurt F, Çarlıoğlu A, Köroğlu M, Uz B, Kasapoğlu B. Is the thyroid function a risk factor for obesity? N Engl J Med 2009;26:27-30.