[Variation in high density lipoprotein cholesterol during treatment of thyroid gland diseases]

Serum cholesterol concentration is usually increased in primary hypothyroidism and decreased in hyperthyroidism. The role of hypercholesterolemia in hypothyroidism as a causal factor for coronary atherosclerosis has been extensively discussed. Epidemiologic studies have stablished that there is a very strong negative correlation between plasma HDL cholesterol levels and coronary atherosclerosis. Plasma concentration of HDL cholesterol was determined in 36 controls after separation of HDL from other lipoproteins by ultracentrifugation (uc), by precipitation by heparin-manganese chloride (hmc) and by phosphotungstate magnesium chloride (pmc). The recovery of HDL after both precipitations was almost 100% as shown by HDL immunoassay (kit Behring). There was a very strong correlation between cholesterol HDL values obtained by uc and hmc (r = 0.91) and by uc and pmc (r = 0.90). Normal values were 1.22 +/- 0.27 mmol/1 (mean +/- SD) in males and 1.57 +/- 0.31 mmol/L in females. We have measured HDL cholesterol by both precipitation technics in 17 hypothyroid patients before and under treatment for at least 2 months. Plasma total cholesterol levels were 7.01 +/- 2.61 mmol/1 before and 4.94 +/- 0.85 mmol/1 after treatment (p < 0.001); in contrast plasma HDL cholesterol did not change (1.29 +/- 0.33 vs 1.28 +/- 0.38 mmol/1). In 11 hyperthyroid patients plasma total cholesterol was 4.14 +/- 1.03 before and 5.74 +/- 0.88 mmol/l after recovery (p < 0.001). The mean plasma HDL cholesterol did not change (1.43 +/- 0.23 vs 1.59 +/- 0.42 mmol/1). However, 5 out of 11 patients had an increase of more than 10% of the plasma HDL cholesterol levels.