Subclinical thyroid dysfunction and cardiac function amongst minority ethnic groups in the UK: a cross sectional...

Area of Science:

• Endocrinology
• Cardiovascular Medicine
• Public Health

Background:

• Subclinical thyroid disease (STD) is linked to abnormal cardiovascular hemodynamics and heart failure risk.
• The prevalence and impact of STD in UK South Asian (SA) and African-Caribbean (AC) populations are not well-defined.
• These ethnic groups have a higher susceptibility to cardiovascular disease (CVD).

Purpose of the Study:

• To determine the prevalence of subclinical thyroid disorders in SA and AC populations in the UK.
• To investigate if STD is associated with abnormal cardiac function and heightened cardiovascular risk in these ethnic groups.

Main Methods:

• Analysis of SA (n=1111) and AC (n=763) participants from a heart failure screening study.
• Definitions: Euthyroidism (TSH 0.4-4.9 mlU/l), Subclinical Hypothyroidism (raised TSH, normal FT4 9-19 pmol/l), Subclinical Hyperthyroidism (low TSH, normal FT4 & FT3 2.6-5.7 pmol/l).

Main Results:

• Prevalence of subclinical hypothyroidism was 2.9%, and subclinical hyperthyroidism was 2.0% across ethnic groups.
• Hyperthyroidism was more common in SA (2.8%) than AC (0.9%) (P=0.017); hypothyroidism rates were similar.
• Ethnicity was not an independent factor in subclinical thyroid function variations on multivariate analysis.

Conclusions:

• The prevalence of subclinical thyroid disorders in UK SA and AC minority groups is comparable to other populations.
• The clinical cardiovascular implications of subclinical thyroid disease remain uncertain.
• Subclinical thyroid disease does not appear to have ethnic specificity regarding its prevalence or impact.