Your body needs thyroid hormones to make cholesterol and to get rid of the cholesterol it doesn't need.
When thyroid hormone levels are low (hypothyroidism), your body doesn't break down and remove LDL cholesterol as efficiently as usual. LDL cholesterol can then build up in your blood.
Thyroid hormone levels don't have to be very low to increase cholesterol. Even people with mildly low thyroid levels, called subclinical hypothyroidism, can have higher than normal LDL cholesterol.
A 2012 study found that high TSH levels alone can directly raise cholesterol levels, even if thyroid hormone levels aren't low.
Studies reported that patients with TSH levels at the upper limit of the normal range (thus with normal thyroid hormone levels) were more likely to have higher cholesterol levels as compared with those with lower TSH levels.
Normal TSH is 1.4 — with an ideal range of 0.7 to 2.0. Anything above 2.5 indicates some combination of Metabolic Syndrome and / or Thyroid Insufficiency.
The takeaway is to give focus to your TSH in the event there is hyperlipidemia and treat accordingly: Improving unfavorable lipids could be as simple as fixing the thyroid.
