Decreased lipid intermediate levels and lipid oxidation rates despite normal lipolysis in patients with hypothyroidism.

Background: Hypothyroidism decreases energy expenditure and combustion of fuels, but the reported effects on lipid metabolism and insulin sensitivity are divergent and there is a lack of studies assessing rates of lipolysis and lipid oxidation. The present study was conducted to test the hypotheses that hypothyroidism decreases lipolysis, blood concentrations of free fatty acid, lipid oxidation, and insulin sensitivity.

Methods: We studied 11 hypothyroid patients (thyroid-stimulating hormone: 150 mU/L) with autoimmune thyroiditis (i) before and (ii) after 2 months of triiodothyronine-euthyroidism upon levothyroxine treatment and (iii) compared the patients to 10 healthy volunteers.

Reduced expression of uncoupling protein 2 in adipose tissue in patients with hypothyroidism.

Context: Thyroid disease is associated with major metabolic changes, comprising changes in lipid metabolism. Thyroid hormones have previously been shown to increase UCP2 mRNA expression in fat biopsies from hyperthyroid patients, but data from hypothyroid patients have so far not been reported.

Patients And Methods: Eleven hypothyroid patients were studied before and after l-T(4) replacement, and 10 healthy controls matched for sex, age, and body mass index were studied once.

Serum ghrelin levels are increased in hypothyroid patients and become normalized by L-thyroxine treatment.

Context: An interaction between ghrelin, which is implicated in the regulation of short- and long-term energy balance, and thyroid function has been reported in hyperthyroidism in which ghrelin levels are reversibly suppressed. We measured serum ghrelin levels and metabolic indices in hypothyroid patients before and after L-thyroxine replacement.

Patients And Methods: Eleven patients were examined twice: 1) in the hypothyroid state and 2) after at least 2 months of euthyroidism.

Dose-response effects of free fatty acids on amino acid metabolism and ureagenesis.

Aim: Free fatty acids (FFAs) are important fuels and have vital protein-sparing effects, particularly during conditions of metabolic stress and fasting. However, it is uncertain whether these beneficial effects are evident throughout the physiological range or only occur at very high FFA concentrations. It is also unclear whether secondary alterations in hormone levels and ketogenesis play a role.

Effects of free fatty acids, growth hormone and growth hormone receptor blockade on serum ghrelin levels in humans.

Background: Circulating ghrelin levels are reported to be suppressed by insulin, GH and free fatty acids (FFAs). However, insulin, GH and FFA levels are all interdependent, and it is therefore difficult to delineate their independent effects on ghrelin secretion.

Objective: To isolate and define the impact of GH, GH receptor (GHR) blockade and intravenous FFA infusion on total circulating ghrelin levels during a hyperinsulinaemic glucose clamp with identical insulin levels.