At what time should a nurse plan to have a blood specimen obtained for a serum lithium level determination?

The timing of obtaining a blood specimen for serum lithium level determination is crucial for ensuring accurate results. It is recommended that the blood sample be drawn before breakfast, ideally in the morning, to reflect the trough level of the medication in the patient's system. This is typically when lithium levels are at their lowest after the patient's last dose and allows healthcare providers to assess whether the patient’s lithium concentration is within the therapeutic range before administering the next dose.

Obtaining the sample at other times, such as after lunch or during the afternoon, may result in elevated lithium levels due to ingestion of the medication, which could mislead clinical decisions. Additionally, drawing the specimen before bedtime does not align with standard practice, as it may capture levels that are artificially high. Therefore, the optimal time for serum lithium level determination is indeed before breakfast to ensure accurate monitoring of the drug’s efficacy and safety.