Broda Barnes book [1] says, iirc, that high cholesterol levels are basically diagnostic of hypothyroidism. Usually people's superficial thyroid lab #'s look fine (TSH), but their body is not properly activating T4 -> T3.
[0] http://tpauk.com/main/the-tsh-reference-range-wars/
[1] http://www.ncbi.nlm.nih.gov/pubmed/18443261?dopt=AbstractPlu...
[2] http://perfecthealthdiet.com/2010/07/thyroid-more-evidence-t...