Understanding lithium lab results

Hi @annedallas

I ran it by Claude.ai and this is the response

MY query: A person's lab results were reported as follows " showed his lithium level to be "under 0.3 L" and the reference range to be "0.6-1.2 mmol/L". Since the other values are in mmol/L, is the "under 0.3 L" an error?

Claude's answer:
"Yes, almost certainly a transcription or reporting error.
Here's why:
"L" alone is not a valid unit for a blood concentration. Lithium levels are always reported as a concentration — meaning an amount of substance per volume of fluid. The standard units used are:
- mmol/L (millimoles per litre) — most common internationally
- mEq/L (milliequivalents per litre) — used in some US labs; numerically identical to mmol/L for lithium
- mg/L or mg/dL — less common but used in some settings
"L" alone (just "litres") is a unit of volume, not concentration, and makes no scientific sense for a blood test result.

Most likely explanation
The "L" is almost certainly a truncation of "mmol/L" — the units were cut off, leaving only the last character. This is a common artifact when:
- Results are copied from an electronic health record (EHR) into a report or note
- A table or field cuts off text
- Manual transcription omits part of the unit
So "under 0.3 L" should most likely read "under 0.3 mmol/L", which is consistent with the reference range units and makes clinical sense.

Bottom line
The value itself (< 0.3) is interpretable and clinically meaningful as discussed previously — subtherapeutic — but the unit as written is an error and should be corrected in the record for accuracy and safety. If this appears in a formal document, it would be worth flagging for correction."

So. Check with the doc, but it seems like your LO is most likely 0.3 mmol/L under the lower end of the target range.