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Mental Health Nursing · Chapter 5

The Lithium Level Bench

Lithium is an ion. It is not metabolised, it is cleared by the kidney, and the kidney handles it in the same channels as sodium — so anything that lowers sodium or volume raises the level. Meet Ms Okafor, steady at 0.8 mEq/L on 900 mg daily. Switch on what happened in her week, choose when the blood was drawn, and read what you would do.

What happened in her week

When was the blood drawn?

A lithium level is a 12-hour trough. Draw it 12 hours after the last dose — conventionally the morning draw, before the morning tablet. A sample taken too early catches absorption and reads high; one taken a full day later reads low. Neither can be compared with the therapeutic range, and both have started unnecessary panics and false reassurance.

Chart the shift

Two entries describe the same conversation with Ms Okafor. One belongs in the record. Choose it.

The level, and what it means

0.80mEq/L
Therapeutic
0 0.6 1.2 1.5 2.0 2.5 3.0 therapeutic toxicity above 1.5 0.80

What you would teach her

The sick-day rule prevents more lithium toxicity than any teaching sheet. With vomiting, diarrhoea or fever: hold the dose and call — do not simply carry on. Add consistent salt intake, two to three litres of fluid daily unless contraindicated, acetaminophen rather than ibuprofen for a headache, and a check with the prescriber before any new medicine, including ones bought over the counter.

Why the wording matters

Choose an entry on the leftThe label and the description take the same number of seconds to write. Only one of them is still useful to the nurse who reads it at three in the morning.