Cardiac and metabolic effects in patients who present with a multinodular goitre

Twenty-six consecutive patients who presented with clinically euthyroid multinodular goitre were studied for an overnight fasting serum lipid profile and 24 h Holter monitoring. Mean serum TSH was 0.6 +/- 0.4 vs 2.4 +/- 1.3 mU/l (p < 0.0001) and mean TT3 2.4 +/- 0.4 vs 2.0 +/- 0.5 nmol/l (p = 0.009) in patients vs controls (n = 15) while mean FT4 was not different from controls. Total serum HDL, LDL cholesterol and triglycerides were lower in patients but creatinine, ferritin and SHBG levels did not differ between patients and controls. The 24-hour ambulatory continuous ECG recordings did not demonstrate significant differences in mean, minimal and maximal heart rate between the study and the control group. Nocturnal heart rate, measured between 23.00 and 06.00 hours, also showed no differences between the two groups. Atrial fibrillation was absent in both the study and the control group. Premature atrial and ventricular complexes occurred equally frequently in both groups. Comparison of patients with a serum TSH below 0.4 mU/l (n = 11) and patients with a TSH above 0.4 mU/l revealed no differences. In conclusion, in consecutive patients who present with multinodular goitre, effects were found on the lipid profile, but not on the heart. It is argued that in this type of patients, cardiac effects depend on the degree of subclinical hyperthyroidism.