What belongs in a lithium note if kidney function is the concern?

The current dose, the last serum level and date, eGFR or creatinine with trend, TSH when due, and a line about polyuria, nocturia, or nocturnal thirst. Then the decision: hold, lower, repeat labs, or continue, with a reason tied to those numbers.

What lithium level does the 2026 kidney guidance aim for?

The IGSLi/ISBD task force argues for aiming below 0.80 mmol/L for long-term treatment. The 0.80 to 0.99 band was associated with a much higher rate of CKD. That is a monitoring target, not a reason to yank lithium from someone who only stayed well at 0.9.

Should I stop lithium once eGFR falls?

Not automatically, and not late. The same guidance notes that once eGFR is roughly 30 to 40, decline often continues even after stopping. The work is getting the dose and the level right early, and talking to nephrology when the trend is real.

What belongs in a lithium note if the kidneys are the story?

IGSLi/ISBD puts the risk at mild-to-moderate CKD, not dialysis. The note has to show the level, the eGFR trend, and that you asked about thirst.

A lithium follow-up has to show the level you used, the kidney numbers you saw, and whether they are thirsty at night. The new IGSLi/ISBD opinion is narrower than “lithium ruins kidneys, stop it”: the extra risk is mostly mild-to-moderate CKD, the dangerous part is a high level over years, and stopping late does not undo the slope.

I used to write “lithium 900, level okay, continue.” That sentence has hidden a tremor, a climbing creatinine, and one patient who was drinking a pitcher of water at 2am. The guideline is an excuse to stop writing it.

The numbers that have to appear

Dose and formulation. Lithium carbonate 300 mg at night is not the same as a 450 mg slow-release twice a day. Once-daily dosing is what they want when you can do it. If I split the dose, I say why.

Last level, date drawn, and hours after the dose if I know it. A 0.6 drawn 4 hours after a morning dose is not a trough. I have signed that error.

eGFR or creatinine, and whether it moved. One number is a lab. Two numbers are a story. “eGFR 68, was 74 in March” is a story I have to answer.

TSH when it is due. Thyroid is not the kidney, and I still miss it when I am staring at the creatinine.

Symptoms the template never asks

Polyuria. Nocturia. Nocturnal thirst. The task force wants these every visit. They take twelve seconds. “Sleeping through the night, no extra water” is a negative worth writing. I do not need a fluid diary from someone who is well.

Tremor, diarrhea, confusion, last NSAID, last thiazide, last ACE inhibitor started by cardiology. Lithium toxicity is often a drug someone else added. If I did not ask, I do not write “no signs of toxicity” as a reflex. I have been on that soapbox about the MSE already.

The decision, tied to the numbers

“Lower to 600 mg nightly; last level 0.92, eGFR down 6 points, aiming under 0.8 for maintenance.” That is a lithium note.

“Continue current dose” is allowed when the level is 0.64, eGFR is flat, and they are sleeping. Write those three things so it does not look like you did not look.

If I am not going to stop lithium at an eGFR of 52, I say why: three hospitalizations off it, nephrology already in the loop, level 0.55. The guidance is explicit that switching to valproate is not a renal favor. Do not write “consider depakote for kidneys” as if that were settled.

Past a point, stopping does not save the kidney. They put that point around an eGFR of 30 to 40. That is a conversation with nephrology, not a heroic discontinuation in a 20-minute slot.

What I keep in the same place every time

I use a lithium-shaped follow-up so the labs have a home. We keep a lithium monitoring template for that reason. You can also just type the same six lines. Consistency beats a pretty heading.

If the level is missing, the note says the level is missing, and the plan is to get it, not to pretend last November still counts.

Questions I get

Do I need a level every visit? No. You need a level on the schedule you actually follow, and you need to say when the next one is due. A visit with no level still needs thirst, tremor, and whether anyone started ibuprofen.

Is 0.8 a hard ceiling? It is a long-term kidney target from this task force, not a commandment. If they only stayed well at 0.9, write that tradeoff. Do not silently sit at 1.1 because “that’s the old range.”

What if they refuse labs? Then you do not have a lithium practice, you have a hope. Document the refusal, the risk you named, and whether you are willing to keep prescribing without numbers. I am often not.