Lachezar B Lozanov, Vessela Koleva, Bojan S Lozanov and MiraVankova
Introduction: Hypothyroidism, metabolic syndrome and central obesity are common diseases known as the risk factors for atherosclerotic cardiovascular disease. The co-existence of thyroid dysfunction in obese patients might substantially increase the cardiovascular risk. The objective of the study was to evaluate the effect of hypothyroidism on the main cardiovascular risk factors in patients with obesity and cardiovascular syndrome.
Material and methods: In a cross-sectional clinical study we examined 202 patients with central obesity and metabolic syndrome (160 women, 42 men, aging 43 ± 13 yrs) with BMI ≥ 30 kg/m2 divided in two groups - 101 patients with subclinical or overt hypothyroidism (gr. A-hypot) and 101 eythyroid patients (gr B-eut), diagnosed by TSH, FT4,TPO-Ab. Laboratory assessment included: total cholesterol (TChol), HDL,LDL, triglycerides (3-glyc), serum glucose, standard oral glucose tolerance test (OGTT) and insulin resistance by Homeostasis Model Assessment of Insiline Resistance (HOMA-IR). Serum leptin and C-reactive proteins were estimated in 20 patients of each patients group and in a control group of 20 healthy persons with BMI <25 kg/m2. The supplementation Levothyroxine therapy was carried out of patients with overt and subclinial hypothyroidism.
Results: Both compared groups showed similar BMI (mean 37 kg/m2) and HOMA-IR value 3.1 and 3.15, respectively Mean TSH value was found 4-fold higher in gr. A than in gr. B. which significantly correlated with TChol, 3-glyc, CRP and serum leptin The prevalence of arterial hypertension (AH), diabetes type2 or impaired glucose tolerance (IGT) in gr A was 86% and 67% vs. 80% and 70% in gr B, respectively. Significant correlations were established between TSH, TChol, atherogenic lipoproteins, 3-glyc. in patients gr. A but not in gr B. The same parameters decreased significantly after adequate levothyroxin supplementation. The significant positive nonparametric correlations were found also between BMI, TSH, leptin and CRP (p<0.05).
Conclusion: Our data demonstrate that hypothyroidism significantly aggravates the lipid metabolisms in patients with obesity or MetS. These disturbances co-existing with higher prevalence of arterial hypertension, DM-T2 or IGT determine the substantially increased cardiovascular risk which correlated with increased insulin resistance, higher levels of leptin and CRP as a marker of chronic inflammation. Consequently clinicians shouid be particularly alert in the possibility of thyroid disfunction in obese patients.