Lithium story: eight guidelines, eight recommendations

When I was first prescribed lithium, my psychiatrist told me to take it once daily just before bed, and to get a blood test measuring the trough serum level 12 hours after the previous dose. I was troubled by these instructions. Firstly, I did not understand why my psychiatrist was using the term trough to apply to a lithium serum concentration about halfway between peak and trough serum concentrations. Secondly, I did not understand why my dosing regimen was not twice daily (every 12 hours). Since the therapeutic window of lithium is very small, splitting the dose would have produced a narrower peak-to-trough serum lithium level. Thirdly, I did not know why a peak lithium level blood test was not asked for. I was under the impression acute toxicity was the danger when starting lithium.