Charles Dickens, Micawber and thyroid dosing
Mr Micawber’s famous, and oft-quoted, recipe for happiness:
“Annual income twenty pounds, annual expenditure nineteen [pounds] nineteen [shillings] and six [pence], result happiness. Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.”
If you take 100 micrograms of levothyroxine a day and your body expends 99 micrograms, result happiness. Take 100 micrograms of levothyroxine a day, body expends 101 micrograms, result misery.
Every extra day leaves you further behind, until eventually you reach a new but definitely suboptimal steady state. A tiny, tiny amount more than you need is of little or no consequence.
For example, if you were on 125 micrograms and needed a small dose reduction, say to 112, but you were actually reduced to 100, you would be falling behind by 12 micrograms a day. In one week, you are down by 84 micrograms. Only when your body reduces its “consumption” of levothyroxine to 100 can the new steady state occur – and you will be well down by then.
(Be careful not to interpret this as an invitation to take more and more levothyroxine, that is taking the analogy too far.)