Lipid Profiles and Cardiovascular Disease in the Whickham Area With Particular Reference to Thyroid Failure

Abstract

SUMMARY The age and sex distribution of ischaemic heart disease (IHD), other vascular disorders and serum lipid concentrations and the possible association between these factors and thyroid failure have been examined in a community survey. A past history of IHD occurred in 7.5% of males and 4.8% of females.‘Chest pain on effort’was found in 7.4% of males and 7.8% of females and‘possible infarction’in 5.4% of males and 3.8% of females. Major ECG changes were found in 4.7% of both sexes and minor changes in 6.5% of males and 11% of females. Intermittent claudication was present in 4.8% and cerebrovascular accidents had occurred in 2% of the sample. Diastolic blood pressures greater than 100mmHg were found in 13% of all males and 11% of all females. Cholesterol concentrations were normally distributed. Mean cholesterol rose by approximately 0.25 mmol/1/decade in both sexes to reach a maximum in the 55–64 years age group and declined slightly thereafter. Trigly‐ceride values were skewed to the right and increased by 0.2 mmol/1/decade in males up to the 45–54 years age group and by 0.1 mmol/1/decade in females to a peak in the 65–74 years age group — and declined after these ages. Electrophoresis revealed Type IIa patterns in 3% of males and 9% of females, IIb in 1% of both sexes and Type IV in 13% of males and 3% of females. There was no association in males between IHD and thyroid antibodies or minor degrees of thyroid failure. There was a weak association between minor ECG changes and minor degrees of hypothyroidism (but not thyroid antibodies) in females which was independent of other variables. The significance of this observation depends upon the interpretation of the ECG abnormalities and will only be established by longitudinal studies. No association was noted between lipid concentrations and thyroid antibodies or minor degrees of hypothyroidism.

The lack of association between hypertension and hypothyroidism in a primary care setting

“…26,27 One community-based study has reported higher mean systolic and diastolic blood pressures in women with elevated TSH. 28 However, the analysis was not stratified by age and the women with elevated TSH were significantly older than their euthyroid controls. This same study found no difference in the mean systolic and diastolic blood pressures of hypothyroid and euthyroid men, although unlike the women, these two groups of men were of similar ages.…”

“…[2][3][4][5][6][7] While hypothyroidism is identified as a cause of diastolic hypertension in many medical textbooks [8][9][10][11] and in review articles 1,12 research based on non-referred subjects is contradictory about the association. [13][14][15] Hypothyroidism and diastolic hypertension are both common and have prevalences which increase with age. In the community setting overt hypothyroidism occurs in 1.5% to 2% of women and 0.2% of men.…”

Lipid profile in subclinical hypothyroidism: is L-thyroxine substitution beneficial?

“…However, a precise relationship between overt hypothyroidism and CAD has not been confirmed, although data linking these two conditions have been demonstrated in autopsy studies (1,2). Subclinical hypothyroidism (SH), defined as the clinical status of elevated serum thyrotropin (TSH) levels, with normal levels of thyroxine (T 4 ) and triiodothyronine (T 3 ), is a more common disorder than overt hypothyroidism with a prevalence of 1.4 -7.8% in older populations and even greater percentiles among women (3,4).…”

“…Overt hypothyroidism is associated with abnormalities of lipid metabolism, which may predispose to the development of atherosclerotic coronary artery disease (CAD) (1,2). However, a precise relationship between overt hypothyroidism and CAD has not been confirmed, although data linking these two conditions have been demonstrated in autopsy studies (1,2).…”

“…Subclinical hypothyroidism (SH), defined as the clinical status of elevated serum thyrotropin (TSH) levels, with normal levels of thyroxine (T 4 ) and triiodothyronine (T 3 ), is a more common disorder than overt hypothyroidism with a prevalence of 1.4 -7.8% in older populations and even greater percentiles among women (3,4). Some studies have associated this subtle change in thyroid function with increased risk of CAD (1,(4)(5)(6). Lipid abnormalities would offer the most obvious explanation for this phenomenon, but several studies have shown conflicting results concerning not only the degree of lipid changes in SH but also the effect of L-thyroxine substitution therapy (2,4,7).…”