I've been on lithium almost 11 years now. I've had 2 serious toxicities, the last just over a year ago. Both times I missed it. The first time we all did for a long time because it wasn't very typical and was very hard to test. To get an accurate level you have to have blood drawn 11-13 hours after a dose and have not missed a dose in 4 days. I couldn't go 4 days then without vomiting so we kept testing but it wasn't accurate. I had ulcers from vomiting so much and that additionally made it confusing. Finally Dr. Mind noticed that I couldn't walk straight and contacted Dr. Brain. She pulled me off work so I could focus on keeping meds down (I think I had medicine for that) and the day after I had the blood drawn I got the call from a triumphant Dr. Brain that she knew what had been wrong for months. My level was fairly high but not dangerous so that time it was treated as an outpatient. Last year I suddenly became agitated and in a couple days as hallucinating. I called her and since that's very atypical for me she sent me to the ER. In the ER I kept insisting that I had no symptoms of toxicity. Then the 3rd time through it when an intern was being taught how to evaluate for toxicity I finally caught on that I was failing neuro testing. I know what it looks like, I just was so sure it would be normal that I did not pay attention. That time through it I also realized that there had been some other signs I'd ignored for a few weeks. That time I was very toxic and there were physical things like increased kidney numbers and urine that as practically entirely water (which screws up your electrolytes. I have a problem from lithium called diabetes insipidus that causes this but it as pretty controlled until the toxicity and Dr. Brain said she'd never seen a urine as dilute as mine.) And of course there were the hallucinations and apparently I was pretty confused which I didn't know until I as out of the hospital.
Last night I had some digestive issues that happen only when sick (I'm not) or lithium toxic. When I started putting things together I realized that I've again had several symptoms for a while. So Monday I'll manipulate med times and then go get it drawn after I see Dr. Mind. Chances are good that I'm wrong since I have been tested at my request several times before and I've never been right. For some time after the first toxicity I got toxic every time I got hot or didn't drink enough but it was always just a short spike and then it recovered. Those I was accurate with but they didn't matter.
I just hope that if I am right I have a reason for various oddities of late. And if I'm right I hope that I can stay home and avoid the IV. That was a disaster a year ago. (The hospital, not the IV).
We shall see.