Thyroid function and lipid subparticle sizes in patients with short-term hypothyroidism and a population-based cohort.
BACKGROUND
Relations between thyroid function and lipids remain incompletely understood.


OBJECTIVE
Our objective was to determine whether lipoprotein subparticle concentrations are associated with thyroid status.


METHODS
We conducted a prospective clinical study and cross-sectional cohort analysis at a university endocrine clinic and the Framingham Heart Study.


METHODS
Subjects included 28 thyroidectomized patients with short-term overt hypothyroidism and 2944 Framingham Offspring cohort participants.


METHODS
Fasting subclass concentrations of very-low-density lipoprotein (VLDL), intermediate-density lipoprotein, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) particles were measured by nuclear magnetic resonance spectroscopy. TSH values were also measured.


RESULTS
Total cholesterol and LDL-C were increased during short-term overt hypothyroidism. Large LDL subparticle concentrations increased during hypothyroidism (917+/-294 vs. 491+/-183 nmol/liter; P<0.001), but more atherogenic small LDL was unchanged. Triglycerides marginally increased during hypothyroidism, small VLDL particles significantly increased (P<0.001), whereas more atherogenic large VLDL was unchanged. Total HDL-C increased during hypothyroidism (76+/-13 mg/dl vs. 58+/-15 mg/dl; P<0.001). There was no change in large HDL-C particle concentrations, whereas small (P<0.001) and medium (P=0.002) HDL-C particle concentrations decreased. Among Framingham women, adjusted total cholesterol and LDL-C were positively related to TSH categories (P<or=0.003). This was due to a positive correlation between adjusted large LDL subparticle concentrations and log-TSH (P<0.0001); log small LDL subparticle concentrations decreased slightly as log-TSH increased (P=0.045). Among Framingham men, the only significant association was a positive association between log-TSH and log large HDL subparticle concentrations (P=0.04).


CONCLUSIONS
There is a shift toward less atherogenic large LDL, small VLDL, and large HDL subparticle sizes in hypothyroid women.
Pearce
Elizabeth N
EN
Boston University Medical Center, Department of Biostatistics, Boston University School of Public Health, 88 East Newton Street, Evans 201, Boston, Massachusetts 02118, USA. elizabeth.pearce@bmc.org
Wilson
Peter W F
PW
Yang
Qiong
Q
Vasan
Ramachandran S
RS
Braverman
Lewis E
LE
D000328:Adult; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000378:metabolism / Q000503:physiopathology*; D008074:Lipoproteins / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013961:Thyroid Gland / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood
D008074:Lipoproteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D013972:Thyrotropin