Increased levels of C-reactive protein in hypothyroid patients and its correlation with arterial stiffness in the common carotid artery.
OBJECTIVE
Hypothyroidism is associated with increased morbidity from cardiovascular disease. The arterial stiffness index beta (stiffness beta) in the common carotid artery (CCA), which is a parameter of arterial stiffening, is known to increase in hypothyroid patients, while normalization of thyroid function for 1 year by levothyroxine (L-T(4)) replacement therapy significantly decreases CCA stiffness beta. Since serum C-reactive protein (CRP) has recently emerged as an independent factor for cardiovascular risk, the present study was designed to examine whether hypothyroidism causes an increase in CRP and whether the serum CRP level is correlated with CCA stiffness beta in hypothyroid patients.


METHODS
Serum CRP levels and CCA stiffness beta were determined in 46 patients with hypothyroidism and in 46 age- and sex-matched normal control subjects. Thirty-five patients were further monitored for change in CCA stiffness beta during 1 year in the euthyroid state induced by L-T(4) therapy.


RESULTS
Baseline CRP and CCA stiffness beta were both significantly higher in hypothyroid patients than in normal controls [1064.6+/-224.3 vs. 602.1+/-43.3 ng/ml (mean+/-SE), p<0.0001; and 9.25+/-0.84 vs. 8.21+/-0.85, p<0.05, respectively]. Baseline CRP was significantly correlated in a positive manner with baseline values of CCA stiffness beta (r=0.683, p<0.0001). In multivariate analysis, baseline CCA stiffness beta was significantly associated with baseline levels of serum CRP (r=0.740, p<0.0001). During 1 year of L-T(4) replacement therapy, significant decrease in stiffness beta (from 9.25+/-0.84 to 8.57+/-0.58, p<0.0001) to the normal levels was found. Moreover, the change in CCA stiffness beta during L-T(4) replacement therapy was significantly and independently associated in a negative fashion with baseline levels of serum CRP (r=-0.696, p=0.0002).


CONCLUSIONS
This study suggests that increased serum CRP might have an important independent role in increased arterial stiffening and the measurement of serum CRP is a useful predictor for the degree of improvement of arterial stiffening in hypothyroid patients.
Nagasaki
Toshiki
T
Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
Inaba
Masaaki
M
Shirakawa
Kumi
K
Hiura
Yoshikazu
Y
Tahara
Hideki
H
Kumeda
Yasuro
Y
Ishikawa
Tetsuro
T
Ishimura
Eiji
E
Nishizawa
Yoshiki
Y
D001158:Arteries / Q000503:physiopathology*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis / Q000378:metabolism*; D017536:Carotid Artery, Common / Q000503:physiopathology*; D004548:Elasticity; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000503:physiopathology*; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012737:Sex Factors; D013974:Thyroxine / Q000494:pharmacology
D015415:Biomarkers; D002097:C-Reactive Protein; D013974:Thyroxine