Labs for Low Dose Lithium

[SpongeBob DoctorPants]

When using low doses of lithium, as an adjunct to antidepressant therapy or for suicidal thoughts, when does it become necessary to get labs? My understanding is that it's not necessary to check the lithium level, etc. at very low doses, such as 150 or 300 mg per day, but what about if the dose is increased from there such as 450 mg daily? Any guidelines on this?

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[SpinDktr]

I would personally still check kidney function even on low doses of 150. It's part of the patient education that it needs to be monitored, can have interactions with other medications, etc. I probably would not get a level until you get to 300 or over, but I still sometimes do. I am more cautious than most. People tend to forget so many things, and if you give them something tangible like a lab result, they tend to listen more and pay more attention to what you are saying.

 

[wolfvgang22]

I'd still check the lithium level. This is how I found out one patient was taking three times the prescribed dose.

 

[Mkitties]

When using low doses of lithium, as an adjunct to antidepressant therapy or for suicidal thoughts, when does it become necessary to get labs? My understanding is that it's not necessary to check the lithium level, etc. at very low doses, such as 150 or 300 mg per day, but what about if the dose is increased from there such as 450 mg daily? Any guidelines on this?

I usually don't check a Lithium level unless I increase the dose above 300mg. However I do encourage annual blood work including CMP, TSH, etc.

 

[michaelrack]

I always check a level. I have seen relatively high levels 0.8 or 0.9 on 300 mg per day for unclear reasons

 

[ara96]

I always check a level. I have seen relatively high levels 0.8 or 0.9 on 300 mg per day for unclear reasons

Perhaps they were taking it more than once a day.

 

[michaelrack]

Perhaps they were taking it more than once a day.

No, I do only inpatient Psychiatry

 

[st2205]

I had an old lady I started lithium on at 150 bid. Lab a few days later was 1.1. I had assumed they didn’t get a true trough but when I spoke to the family she was having tremors. Reduced down to 150 once daily for the next couple days and drew another level that was 2.4.

 

[clausewitz2]

I had an old lady I started lithium on at 150 bid. Lab a few days later was 1.1. I had assumed they didn’t get a true trough but when I spoke to the family she was having tremors. Reduced down to 150 once daily for the next couple days and drew another level that was 2.4.

On C&L once I saw a lady who was on Li 300 qHS who got admitted for acute delirium and what ended up being a Li level of 3.5 without any history of kidney disease. After she was discharged her step-down doc put her on Li 150 mg qHS and she was back in the hospital delirious 3 days later with a toxic level. Some people just have weird kidneys.

 

[SpongeBob DoctorPants]

Thanks for the input, everyone! This is very helpful.

 

[ara96]

On C&L once I saw a lady who was on Li 300 qHS who got admitted for acute delirium and what ended up being a Li level of 3.5 without any history of kidney disease. After she was discharged her step-down doc put her on Li 150 mg qHS and she was back in the hospital delirious 3 days later with a toxic level. Some people just have weird kidneys.

Wow, really weird.

 

[NickNaylor]

I would still check all of the recommended monitoring labs regardless of the dose. I’m working with an attending on a poster/lecture presentation discussing acute lithium toxicity despite therapeutic doses in the low-normal range without any evidence of intentional or accidental overdose. Even with a dose that might lead you to believe that there’s minimal or “no” risk of toxicity, it can still happen.

In the very unlikely event someone develops hypothyroidism or renal insufficiency that you fail to identify because “they were on a low dose and didn’t think the monitoring was indicated,” you’d be in a pretty indefensible position from a liability standpoint.

 

[michaelrack]

Li is a powerful drug, and you have to treat it with respect