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Serum paraoxonase activity before and after treatment of thyrotoxicosis
Author(s) -
Raiszadeh Farbod,
Solati Mehrdad,
Etemadi Arash,
Azizi Fereidoun
Publication year - 2004
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2004.01940.x
Subject(s) - paraoxonase , euthyroid , medicine , endocrinology , aryldialkylphosphatase , lipoprotein , apolipoprotein b , oxidative stress , high density lipoprotein , cholesterol , pon1 , thyroid , chemistry , biochemistry , genotype , gene
Summary objective Antioxidant effects of paraoxonase, a high density lipoprotein (HDL)‐associated enzyme that inhibits low density lipoprotein cholesterol (LDL‐C) oxidation in human serum, have been reported. Patients with thyroid dysfunction are more susceptible to oxidative stress, and may show enhanced LDL‐C oxidation. The purpose of this study was to evaluate serum paraoxonase activity in patients with hyperthyroidism before and after treatment with methimazole (MMI). design and patients Twenty‐four hyperthyroid patients (15 women and nine men, aged 43·0 ± 12·9 years) and 23 age‐ and sex‐matched healthy controls were studied. Serum paraoxonase activity, lipid, lipoprotein and apolipoprotein levels were measured in fasting samples. Patients were treated with MMI 20–30 mg daily for the first month, and 5–10 mg daily thereafter, and re‐evaluated after 6–9 months of treatment. results Significantly lower serum paraoxonase activity was present in hyperthyroid patients before treatment compared with the controls (43·4 ± 21·9 vs. 72·6 ± 41·2 U/ml, P < 0·005). After a mean follow‐up of 7·3 months, 15 patients became euthyroid (treated) and nine were still hyperthyroid. After follow‐up, serum paraoxonase activity had increased to 62·2 ± 37·4 U/ml in those who became euthyroid ( P < 0·05 compared with baseline). In patients who were still hyperthyroid serum paraoxonase was unchanged from baseline, at 43·2 ± 23·2 U/ml. conclusion Serum paraoxonase is reduced in patients with hyperthyroidism and reverts to normal after euthyroidism is attained. Reduced serum paraoxonase activity in thyrotoxicosis might predispose lipids to oxidation.