Thyroid levels can affect cholesterol, and energy. His thyroid my have nodules on it, making it difficult to swallow and making his throat sore. He may be sensitive to cold or hot, have hair breaking off or sudden bald spots.

My SO has thyroid problems. Over time they upped her replacement therapy so much that she had super-naturally low cholesterol. Most of her health care providers responses were....wow we don't see a problem. How lucky you are to have such great cholesterol.

Hopefully your friend is able to get to a diagnosis quickly, whatever it is.