Do in-vivo suppression and stimulation of lipolysis influence thyroid hormone levels in man?

To determine whether increases in non-esterified fatty acids alter free thyroid hormone and TSH levels, the effect of endogenous activation of lipolysis by insulin-induced hypoglycaemia was examined in seven healthy volunteers pretreated with placebo or acipimox. Whilst levels of non-esterified fatty acid were very different in the two groups, levels of free thyroxine, tri-iodothyronine and TSH were unchanged. Thus, within the range of non-esterified fatty acid levels likely to be seen in clinical practice, any effect on thyroid hormone measurements can be safely ignored.