Relationship of TSH Levels with Cardiometabolic Risk Factors in US Youth and Reference Percentiles for Thyroid Function

Abstract

Context Thyroid hormones play an important role in the metabolic homeostasis and higher levels have been associated with cardiometabolic risk. Objective To examine the association of cardiometabolic risk factors with TSH levels in US youth. Design & Setting Cross-sectional study of youth aged 12-18 years without known thyroid abnormalities from five National Health and Nutrition Examination Survey cycles (n=2,818) representing 15.4 million US children. Subclinical hypothyroidism (SH) was defined as TSH levels 4.5-10 mIU/L. Assessed cardiometabolic risk factors include abdominal obesity (waist circumference > 90 th percentile), hypertriglyceridemia (TG ≥130 mg/dL), low HDL cholesterol (HDL-C < 40 mg/dL), elevated blood pressure (SBP and DBP ≥90 th percentile), hyperglycemia (FBG ≥100 mg/dL, or known diabetes), insulin resistance (HOMA-IR > 3.16) and elevated alanine transferase (ALT ≥ 50 U/L for boys and ≥ 44 U/L for girls). Age and sex- specific percentiles for thyroid parameters were calculated. Results In this cohort of youth (51.3% male), 31.2% had overweight/obesity. The prevalence of SH was 2.0 % (95% CI 1.2-3.1). The median TSH levels were higher in youth with overweight/obesity (p<.001). Adjusting for age, sex, race/ethnicity and obesity, youth with TSH in the 4 th quantile had higher odds of abdominal obesity (OR 2.53 [1.43-4.46], p = .002), insulin resistance (OR 2.82 [1.42-5.57], p=.003) and ≥ 2 CMRF (OR 2.20 [1.23-3.95], p=.009). Conclusions The prevalence of SH is low in US youth. The higher odds of insulin resistance and cardiometabolic risk factors in youth with TSH levels > 75 th percentile requires further study.

Thyroid Function in Adults with Prader–Willi Syndrome; a Cohort Study and Literature Review

“…It is important to note that the diagnosis of subclinical hypothyroidism is less reliable in adults with PWS. In the general population, TSH can be affected by obesity [19][20][21][22]. Furthermore, hypothyroidism can be both primary and central in PWS.…”

“…Serum TSH concentrations in patients with central hypothyroidism are often normal [70][71][72]. Furthermore, TSH can be affected by obesity [19][20][21][22]. Taken together, this means that TSH is less reliable in PWS.…”

Association between thyroid autoimmunity and gestational diabetes mellitus in euthyroid women

“…One pathway is via higher serum TSH levels, since TAI is the most frequent cause of hypothyroidism, and the latter has been associated with IR as reviewed in detail by Biondi et al ( 3 ). Already in infants, higher serum TSH levels have been associated with IR through a reduction in blood flow in the skeletal muscle and adipose tissue and decreased glucose uptake via lesser expression of the GLUT-4 glucose transporter ( 25 ). In a recent study, another hypothesis was brought forward to explain the association between thyroid disorders and GDM.…”

“…Another pathway that can link TAI and GDM is via inflammatory pathways that are common in both conditions ( 24 , 25 , 27 ). In one study, levels of serum interleukin‐6 (IL‐6), tumor necrosis factor‐α, IL‐12, IL‐10, and IR (HOMA‐index) were investigated in women with Hashimoto’s disease, in euthyroid women with TAI and a control group ( 27 ).…”

Association between thyroid autoimmunity and gestational diabetes mellitus in euthyroid women

“…One pathway is via higher serum TSH levels, since TAI is the most frequent cause of hypothyroidism, and the latter has been associated with IR as reviewed in detail by Biondi et al (3). Already in infants, higher serum TSH levels have been associated with IR through a reduction in blood flow in the skeletal muscle and adipose tissue and decreased glucose uptake via lesser expression of the GLUT-4 glucose transporter (25). In a recent study, another hypothesis was brought forward to explain the association between thyroid disorders and GDM.…”