A nurse reviews the laboratory report for a client who is receiving lithium three times daily PO. The client's current blood lithium level is 1.8 mEq/L. The nurse identifies that this lab value indicates which of the following?

The lithium level is within the therapeutic level for initial treatment.

A blood lithium level of 1.8 mEq/L is not within the maintenance treatment level.

The lithium level is below the therapeutic treatment level.

The lithium level is at the toxic level.