Objective - Alterations of the lipid profile are a well known phenomenon in
thyroid dysfunction. Thyroid hormones regulate lipid metabolism through va
rious mechanisms, but a key role is played by the LDL receptor pathway, Thy
roid hormone influence on lipoprotein (a) [Lp(a)] metabolism is known.
Methods and results - Therefore we studied Lp(a) concentrations in a group
of 16 hypothyroid patients and in a group of 22 hyperthyroid patients. Twen
ty-six euthyroid subjects were used as a control group. Plasma Lp(a) concen
trations in hyperthyroid patients (23.2 +/- 28.1 mg/dl) were significantly
lower than those of the hypothyroid patients (27.1 +/- 19.2, p < 0.05), The
re were negative correlations between plasma Lp(a) concentrations and total
T-4 levels in patients with hyperthyroidism and hypothyroidism (r: -0.49,
P < 0.05; r: -0.40, P < 0.05, respectively). Also, decreased HDL-C levels,
increased LDL-C, total cholesterol and apo B levels in the hypothyroid pati
ents according to euthyroid subjects were observed (P < 0.05), Decreased LD
L-C levels, increased HDL-C and apo Al levels in the hyperthyroid patients
according to euthyroid subjects were determined (P < 0.05).
Conclusions - It was concluded that plasma Lp(a) concentrations increase in
hypothyroid patients and the observed relationships between thyroid status
and Lp(a) levels can be explained by impaired catabolism of apo B and Lp(a
) in hypothyroidism.