Impaired Hemorheological Parameters and Increased Carotid Intima-Media Thickness in Children with Subclinical Hypothyroidism.

Background: Subclinical hypothyroidism (SH) is defined as elevated serum thyroid-stimulating hormone (TSH) concentration associated with normal serum-free thyroxine levels. Effects of hypothyroidism on hemorheology had widely attracted the attention of researchers during the last decade.

Objective: The purpose of this study is to determine alterations in hemorheological parameters and carotid intima-media thickness (CIMT) in children with SH.

Methods: Fifty-three SH children and 31 healthy controls were enrolled. Erythrocyte deformability and aggregation were determined by an ektacytometer and plasma viscosity (PV) by a cone-plate rotational viscometer. CIMT was evaluated sonographically.

Results: Erythrocyte deformability of the SH group measured at 0.53 and 1.69-30 Pa was lower than that of the control group. The erythrocyte aggregation index, aggregation half time and PV were not different between the groups. However, the aggregation amplitude and mean corpuscular hemoglobin concentration were significantly higher in SH compared to the control group. There was a negative correlation between TSH and deformability values measured at 5.33-30.0 Pa. CIMT in patients with SH was significantly higher than in the control group (p = 0.001; SH = 0.48 ± 0.04 mm, control group = 0.43 ± 0.03 mm).

Conclusion: Impaired hemorheology and increased CIMT are well-known risk factors for developing cardiovascular pathologies. The results of the current study suggest the treatment of children with SH in order to avoid early circulatory problems.