Endocrine Abstracts

Hypothyroidism is associated with higher risk of cardiovascular disease and increase of blood lipids. Previous evidence indicates that high dosage of levothyroxine could be cardiotoxic. There are fewer data describing mortality in subjects after treatment and stabilization of thyroid diseases and there are no data related to subjects with treated hypothyroidism. Aim of this study was to investigate correlations between the cardiovascular risk and metabolic status [Resting Energy Expenditure (REE),and Respiratory Quotient (RQ)], body composition and levothyroxine dosage in a population of patients affected by hypothyroidism. Twenty-five subjects (BMI=28.4±5.5 kg/m², range: 52.3–112.9 kg; age 52.6±13.1 years) affected by hypothyroidism were analyzed. The cardiovascular risk was evaluated using skin autofluorescence via Age Reader instrumentation as well as estimated by Procam and Framingham index. Anthropometric and hormonal parameters (TSH, FT4 and FT3) were evaluated at baseline. REE was measured by indirect calorimetry and fat mass was evaluated by Air Displacement Plethysmography. Fourteen subjects had a high cardiovascular risk (HCVD group) and 11 had a low cardiovascular risk (LCVD group). Comparing REE (measured vs predicted, %), fat mass (kilograms) and levothyroxine dosage (mcg) in HCVD and in LCVD group, a significant difference (P< 0.05) was found at baseline. The HCVD group showed lower REE %, higher fat mass and higher dosage of levothyroxine, compared to LCVD group. No significant differences were found in metabolic parameters (TSH, FT4, FT3) and in lipid profile (total cholesterol, HDL, LDL, triglycerides) between HCVD and LCVD. Patients with hypothyroidism treated with high dosage of levothyroxine had a major risk to develop a cardiovascular disease, a reduced REE and an excess of fat mass. Therefore, this study suggests that, among subjects affected by hypothyroidism, a reduced REE, an increased fat mass and a higher dosage of levothyroxine could be predictive of an increased cardiovascular risk.