Age 42;wt: 61kg;t3-0.86, t4-9.60, tsh-1.91ng/ml;on thyroxine soudium 60mcg (past 16 years), lysteda for dub (past 3 years), LDL 160, reason for high ldl?

Genetic. Only about 10-15% of LDL can be controlled by diet. For many people, the liver just makes too muich cholesterol.
Many Possibilities. Causes of high LDL include genetic (familial hypercholesterolemia, familial combined hyperlipidemia) and non-genetic (insulin resistance, type II diabetes, thyroid abnormalities, chronic kidney disease, alcohol) issues. With a TSH.