Before starting

Required

• Baseline
  • Body weight or Body mass index
  • Cardiac function · especially in patients with cardiovascular disease or at risk who may require ECG.
  • Estimated glomerular filtration rate
  • Full blood count
  • Serum calcium
  • Thyroid function tests · patients should be euthyroid before initiation
  • Urea and electrolytes

After started or dose changed

Required

• At one week; then weekly until levels stable; then every 3 months for first year
  • Lithium levels · take sample just prior to time of next dose (i.e. trough level 12 hours following last dose)

Ongoing once stable

Required

• Every 3 - 6 months
  • Lithium levels · take sample just prior to time of next dose (i.e. trough level 12 hours following last dose)
• 6 monthly
  • Body weight or Body mass index
  • Estimated glomerular filtration rate
  • Serum calcium
  • Thyroid function tests
  • Urea and electrolytes

Monitor lithium levels more frequently in high risk patients

More frequent monitoring (at least 3 monthly) may be required in the following patients:

• Age 65 years and older
• Taking drugs that interact with lithium
• Risk of impaired renal function: e.g. eGFR declines over two or more tests; or urea and creatinine elevated
• At risk of impaired thyroid function
• Raised calcium levels or other complications
• Significant change in a patient’s sodium or fluid intake
• Have poor symptom control or poor adherence
• The last serum-lithium concentration was 0.8 mmol/litre or higher

Abnormal results

Risk of toxicity

Lithium toxicity occurs at serum lithium concentrations of approximately 1.5 mmol/L and above, but may occur despite an apparently normal plasma level. The risk of toxicity is greater in people with hypertension, diabetes, congestive heart failure, chronic renal disease, schizophrenia, Addison’s disease, and COVID-19.

Signs and symptoms

Signs of lithium toxicity include increasing diarrhoea, vomiting, anorexia, muscle weakness, lethargy, dizziness, ataxia, lack of coordination, tinnitus, blurred vision, coarse tremor of the extremities and lower jaw, muscle hyper-irritability, choreoathetoid movements, dysarthria, and drowsiness.

Action required

If lithium toxicity is suspected, do an urgent lithium level immediately and seek specialist advice.

For patients with symptoms of lithium toxicity (e.g. diarrhoea, vomiting, tremor, mental state changes, or falls):

• withold lithium
• take urgent serum lithium level and U&Es
• seek specialist advice

Referral to secondary care may be required depending on the severity of symptoms and the certainty of toxicity. Use clinical judgement to determine the urgency of referral.

Renal function

Monitor dose and blood levels more closely and assess the rate of renal function deterioration in the following circumstances:

• Elevated urea levels
• Elevated creatinine levels
• Decline in eGFR

Notes

Advice to patients

Advise patients to maintain adequate fluid intake and avoid dietary changes which reduce or increase sodium intake. Advise patients to avoid taking NSAIDs over the counter.
Advise patients to report signs and symptoms of:

• lithium toxicity
• hypothyroidism
• renal dysfunction (including polyuria and polydipsia)
• benign intracranial hypertension (persistent headache and visual disturbance)

Prescribing by brand

Preparations vary widely in bioavailability and therefore should be prescribed by brand. Switching from one brand or preparation to another preparation requires the same precautions as initiation of treatment.

Bibliography

• David Taylor, Thomas R.E. Barnes and Allan H. Young. The Maudsley. Prescribing Guidelines in Psychiatry – 13th Edition 2018 [citied 30/07/2020]
• Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press [cited 30/07/2020]
  Essential Pharma. Summary of Product Characteristics – Camcolit 400 mg, controlled release Lithium Carbonate. Last revised 12/2019 [cited 30/07/2020]
• British Medical Journal Journals. Using lithium safely. Drug and Therapeutics Bulletin 1999;37:22-24. [cited 30/07/2020]
• Department of Health and Social Care & NHS England and Improvement: Supply disruption alert. Lithium carbonate (Priadel) 200mg and 400mg modified release tablets – Supply Disruption. Issued 21/08/2020 [cited 01/09/2020]
• National Institute for Health and Care Excellence (NICE). Bipolar disorder: assessment and management [CG185]. Sep 2014 [updated Feb 2020; cited 30/07/2020]
• National Institute for Health and Care Excellence (NICE). Clinical Knowledge Summary. Bipolar disorder: Lithium. Last revised April 2021 [cited 27/07/2021].
• McAllister-Williams R H, Baldwin D S, Cantwell R, et al. British Association for Psychopharmacology consensus guidance on the use of psychotropic medication preconception, in pregnancy and postpartum 2017. Journal of Psychopharmacology 1–34 [cited 30/07/2020]
• Pharmaceutical Services Negotiating Committee. National Patient Safety Agency – Patient Safety Alert – Safer Lithium Therapy (December 2009) [cited 30/07/2020]

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