Journal of clinical research in pediatric endocrinology 2016 12 23() doi 10.4274/jcrpe.3719
Subclinical hypothyroidism (SH) is defined as elevated serum thyroid stimulating hormone (TSH) level with normal range of free thyroxine (fT4). There are very few studies in the literature reporting on the effect of SH on lipid metabolism and carotid intima-media thickness (CIMT) in children.
The study included 38 children diagnosed with SH and a control group comprising 38 healthy, euthyroid children. Subclinical hypothyroidism was diagnosed based on elevated TSH level (4.2-20 mIU/L) and normal fT4 level measured in two morning fasting blood samples that were obtained at an interval of 2 to 6 weeks. Blood samples were collected by venipuncture in the morning after an overnight fasting.
The patient group included 38 children (22 male, 16 female) with SH and the control group included 38 healthy, euthyroid children (20 male, 18 female). Mean age was 8.1±3.6 (range, 3.5-15) years in the patient group and 8.9±2.4 (range, 4.5-15) years in the control group. In the patient group, total cholesterol (TC), Low-density lipoprotein cholesterol (LDL-C), TC/ High-density lipoprotein cholesterol (HDL-C), and LDL-C/HDL-C were higher compared to the control group (p=0.049, p=0.014, p=0.002, and 0.003, respectively). In the same group, CIMT was significantly higher compared to the control group (p=0.001). The patient group was further divided into two groups depending on serum TSH level: (I) patients with mild TSH (TSH=4.2‑10 mIU/L) (n=33) and (II) patients with severe TSH (TSH≥10 mIU/L) (n=5). However, no significant difference was found between the patients with mild and severe TSH with regards to TC, LDL-C, HDL-C, triglyceride level, and CIMT (p=0.635, p=0.424, p=0.310, p=0.342, and 0.610, respectively).
Subclinical hypothyroidism lead to increased dyslipidemia (increased TC and LDL) and increased CIMT, which leads to increased risk of cardiovascular disease. Further studies are needed to substantiate these findings in children with SH.