Levothyroxine replacement for 6 months significantly reduced total and LDL cholesterol and decreased mean carotid intima-media thickness by 11% (P<0.0001).
RCT (n=45)
Double-blind
randomized
Does levothyroxine replacement improve lipid profile and reduce carotid intima-media thickness in patients with subclinical hypothyroidism?
Levothyroxine replacement in patients with subclinical hypothyroidism improves the atherogenic lipoprotein profile and reduces carotid intima-media thickness, suggesting a potential reduction in cardiovascular risk.
p-value: p=<0.0001
Subclinical hypothyroidism (sHT) is associated with dyslipidemia and enhanced cardiovascular risk. We assessed carotid artery intima-media thickness (IMT, high-resolution ultrasonography) and lipoprotein profile in 45 sHT patients (aged 37 +/- 11 yr) at baseline and after 6 months of randomized, placebo-controlled L-T(4) replacement. In comparison with 32 age- and sex-matched controls, sHT patients had elevated total and low-density lipoprotein (LDL) cholesterol and ApoB levels (P = 0.002, P = 0.0007, and P = 0.01, respectively) and higher mean-IMT values (P < 0.0001). In stepwise regression analysis, mean-IMT was positively related (r(2) = 0.71, P < 0.0001) to age, TSH, and LDL cholesterol. L-T(4) replacement significantly reduced both total and LDL cholesterol (P < 0.0001 for both) and mean-IMT (by 11%, P < 0.0001). The decrement in IMT was directly related to the decrements of both total cholesterol and TSH (P = 0.02 and P = 0.0001, respectively). We conclude that early carotid artery wall alterations are present in sHT patients. Whether such IMT increase is related to an early atherosclerotic involvement of the arterial wall cannot be clearly decided on the basis of the present results. However, the fact that L-T(4) replacement therapy was able to improve both the atherogenic lipoprotein profile and intima-media thickening suggests that lipid infiltration of arterial wall may represent a major mechanism underlying IMT increase in subclinical hypothyroidism.
Monzani et al. (Sat,) conducted a rct in Subclinical hypothyroidism (n=45). Levothyroxine (L-T4) vs. Placebo was evaluated on Carotid artery intima-media thickness (IMT) and lipoprotein profile (p=<0.0001). Levothyroxine replacement for 6 months significantly reduced total and LDL cholesterol and decreased mean carotid intima-media thickness by 11% (P<0.0001).