Chemical Pathology


  • Lithium is used in the treatment of bipolar disorder as a modulator of neurotransmission.
  • Lithium levels are indicated for routine therapeutic monitoring; to check compliance; if there is a deterioration in response to treatment; if renal function is fluctuating; when drugs that interact are co-prescribed (e.g. diuretics, ACE inhibitors and NSAIDs), or when toxicity is suspected.
  • Refer to NICE guideline CG185 Assessment and Management of Bipolar Disorder for information on monitoring of lithium therapy.

Sample requirements

  • Samples should be collected 12 hours after the last dose,
  • Minimum re-sampling time is 1 week after any change in dose.
  • Lithium levels should be checked every 3 months and thyroid and renal function every 6 months as a minimum (but check latest NICE guidelines for up to date information)

For adults, 5 ml of blood taken into a narrow gold top tube (or rust top for the Acute Unit)


5ml gold tube


Send at ambient temperature to the laboratory on day of sample collection. If unavoidable, samples can be stored refrigerated overnight.

Required information

Relevant clinical details including other relevant medication, time of last dose and time of sample.

Turnaround times

  • The assays are run throughout the day and night.
  • The in-lab turnaround time is less than 24 hours.
  • The test can be ordered as an urgent request.

Therapeutic ranges

  • NICE Guidelines for Bipolar Disorder CG185 (Sept 2014):
  • Therapeutic Range for Lithium
  • Aim for: 0.6 – 0.8 mmol per litre normally.
  • Psychiatrists may recommend lower or higher target ranges for individual patients.
  • Therapeutic range applies to serum Lithium in a sample taken 12 hours after the Lithium dose.

Further information