Retinol binding protein-4 elevation is associated with serum thyroid-stimulating hormone level independently of obesity in elderly subjects with normal glucose tolerance.
BACKGROUND
Elevated levels of retinol binding protein-4 (RBP4) are positively correlated with insulin resistance, obesity, diabetes mellitus, and cardiovascular disease (CVD). Subclinical hypothyroidism (SCH) has also been associated with CVD; however, the factors linking SCH to CVD are not clear.


OBJECTIVE
The objective of the study was to evaluate risk factors for CVD in elderly patients grouped according to thyroid function.


METHODS
217 subjects (> or =65 yr old) were randomly selected from a population and allocated to a euthyroid group (n = 177) and an SCH group (n = 40) on the basis of plasma concentrations of TSH and free T(4). We included subjects with normal glucose tolerance by a 75-g oral glucose tolerance test and subjects with impaired fasting glucose. We measured anthropometric parameters, levels of fasting glucose and insulin, hemoglobin A(1c), adiponectin, RBP4, lipid profiles, total body fat content, and the area of sc and visceral fat.


RESULTS
The SCH group had higher RBP4 levels than the euthyroid group, irrespective of body mass index and fat content. Subcutaneous and visceral fat areas and total body fat percentage did not differ between groups and were not correlated with RBP4 level. Other CVD risk factors did not differ between groups. RBP4 level was positively correlated with TSH level (r = 0.241, P = 0.001) after adjustment for age, sex, and body mass index.


CONCLUSIONS
Plasma RBP4 levels were associated with SCH independent of obesity in elderly subjects with normal glucose tolerance, indicating that RBP4 level could be used as an index of CVD risk in SCH.
Choi
Sung Hee
SH
Department of Internal Medicine, Bundang Hospital, Seoul National University College of Medicine, 300 Gumi-Dong, Bundang-Ku, Seongnam-Si, Gyeonggi-Do, South Korea.
Lee
You Jin
YJ
Park
Young Joo
YJ
Kim
Ki Woong
KW
Lee
Eun Jung
EJ
Lim
Soo
S
Park
Do Joon
DJ
Kim
Sang Eun
SE
Park
Kyong Soo
KS
Jang
Hak C
HC
Cho
Bo Youn
BY
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000209:etiology; D005260:Female; D005947:Glucose / Q000378:metabolism*; D018149:Glucose Intolerance / Q000097:blood; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications; D008297:Male; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000378:metabolism; D054839:Retinol-Binding Proteins, Plasma / Q000378:metabolism*; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood*
C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma; D013972:Thyrotropin; D005947:Glucose