ABSTRACT
Both overt hypothyroidism [OH] and subclinical hypothyroidism [SH] have been reported to have side effects on body organs. Hypothyroidism can cause hypercholesterolemia, hyperlipidemia and diastolic hypertension, which are regarded as risk factors in development of coronary heart disease [CHD]; on the other hand, the hypercholesterolemia due to hypothyroidism can be easily treated with levothyroxine. This study was performed to determine the prevalence of hypothyroidism in hypercholesterolemic subjects in Mashhad. This descriptive study was performed in Mashhad City from May to Nowember 2002. A number of 4300 men and women aged 40 year or over in 97 different regions in Mashhad were interviewed and 2222 subjecs volenteerly encountered the study. A sample of 12-14 hr fasting blood was taken from volunteers and the total cholesterol [TC] was determined by enzymatic method [zist chime-Iran] for 2215 [758 men and 1457 women] subjects. Serum FT4 and TSH were determined by radio-immunoassay methods for 89 subjects with TC >/= 310 mg/dl and for 82 subjects with TC: 261-309 mg/dl. Individual and laboratory data were gathered in a questionnaire and analyzed using descriptive statistics and frequency destribution tables and X[2] t-test. The results showed that 4.9% of men had TC >/= 310mg/dl, 11.9%, 42.2%, and 41% had TC concentrations of 261-309, 200-260, and <200 mg/dl, respectively. In women with the same TC concentrations were seen in 4.1%, 15.2%, 42.9%, and 37.7%, respectively. In total, 59.4% of men and 63% of women aged over 40 have TC> 200g/dl. Twelve out of 89 [13.5%] subjects with TC>310 mg/dl were hypothyroid; 6 with OH [4women and 2men] and 6 with SH [5women and 1man]. Hypothyroidism in women was more frequent than men and the female /male ratio was 3/1. The correlation between hypercholesterolemia and hypothyroidism at TC>322 mg/dl was significant [X [2]=4.01, df=1, P=0.045]. FT4 level in TC >/= 310mg/dl was 13.05 +/- 3.4, and in TC between 261-309 mg/dl 14.2 +/- 2.63; which was significant in the first group [t-test, p=0.024]. These data demonstrated that hypercholesterolemia is prevalent in mean-aged and elder people in Mashhad and hypothyroidism, especially. SH form, is also frequent in hypercholesterolemic subjects. Female to male ratio is about 3:1, but seemingly younger women in Mashhad are more affected than what is seen in other studies. Therefore, the screening of thyroid function in hypercholesterolemic subjects especially in women is recommended