Thyroid dysfunction and serum lipids: a community-based study.
OBJECTIVE
It is uncertain whether subclinical hypothyroidism (SCH) is associated with hypercholesterolaemia, particularly in subjects with SCH and serum TSH < or = 10 mU/l.


METHODS
Cross-sectional study of 2108 participants in a 1981 community health survey in Busselton, Western Australia. Serum total cholesterol and triglycerides were measured in all subjects and high density lipoprotein cholesterol (HDL-C) measured (and low density lipoprotein cholesterol (LDL-C) calculated) in a subgroup of 631 subjects at the time of the survey. In 2001, TSH and free T4 concentrations were measured on archived sera stored at -70 degrees C. Serum lipid concentrations in subjects with thyroid dysfunction and euthyroid subjects were compared using linear regression models.


RESULTS
In the group as a whole, serum total cholesterol was higher in subjects with SCH (N = 119) than in euthyroid subjects (N = 1906) (mean +/- SD 6.3 +/- 1.3 mmol/l vs. 5.8 +/- 1.2 mmol/l, P < 0.001 unadjusted, P = 0.061 adjusted for age, age(2) and sex). Serum total cholesterol was similarly elevated in subjects with SCH and TSH < or = 10 mU/l (N = 89) (6.3 +/- 1.3 mmol/l, P < 0.001 unadjusted, P = 0.055 adjusted for age, age(2) and sex). In the subgroup analysis, LDL-C was higher in subjects with SCH (N = 30) than in euthyroid subjects (N = 580) (4.1 +/- 1.2 mmol/l vs. 3.5 +/- 1.0 mmol/l, P < 0.01 unadjusted, P = 0.024 adjusted for age, age(2) and sex). LDL-C was significantly increased in subjects with SCH and TSH < or = 10 mU/l (N = 23) (4.3 +/- 1.3 mmol/l, P < 0.001 unadjusted, P = 0.002 adjusted for age, age(2) and sex).


CONCLUSIONS
SCH is associated with increased serum LDL-C concentrations, which is significant after adjustment for age, age(2) and sex.
Walsh
John P
JP
Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia. john.walsh@health.wa.gov.au
Bremner
Alexandra P
AP
Bulsara
Max K
MK
O'leary
Peter
P
Leedman
Peter J
PJ
Feddema
Peter
P
Michelangeli
Valdo
V
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000378:metabolism*; D016014:Linear Models; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood; D014280:Triglycerides / Q000097:blood
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D008055:Lipids; D014280:Triglycerides; D013972:Thyrotropin; D002784:Cholesterol