Here's a good explanation of TSH http://www.stopthethyroidmadness.com/tsh-why-its-useless/. To know thyroid levels, Free T4, Free T3 & Reverse T3 are critical. T4 converts to T3, but for most hypothyroid people this conversion doesn't happen & they remain hypo despite increased doses. Adding more levothyroxine won't help. Levothyroxine (Synthroid) is T4. When there's too much circulating T3, the body converts it to RT3, a form unusable by cells. Several reasons why RT3 could be high, including inadequate cortisol (adrenal hormone) &/or low ferrintin levels (iron stores). Both are needed to get T3 into cells. With the appropriate tests, a ratio of Free T3 & RT3 is known. A healthy ratio is 20 or above. TSH alone tells nothing.
It's not fluctuating levels that effect lipids, but inadequate levels.
We need correct thyroid levels. Why are you concerned about
increased doses with osteopenia?