From the Guidelines
For patients on lithium, regular blood monitoring is essential to prevent toxicity and ensure optimal therapeutic levels, as recommended by the most recent and highest quality study 1.
Key Blood Tests
- Baseline tests should include: + Complete blood count + Renal function (creatinine, BUN, eGFR) + Electrolytes (especially sodium) + Thyroid function tests + Calcium levels + ECG
- Once lithium is started, lithium levels should be checked 5-7 days after initiation or dose changes, then every 3-6 months once stable, as suggested by 2.
Monitoring Frequency
- Renal and thyroid function should be monitored every 6-12 months, as lithium can cause hypothyroidism and impair kidney function over time 2.
- Calcium levels should be checked annually.
- More frequent monitoring is needed for elderly patients, those with medical comorbidities, or if signs of toxicity appear (tremor, confusion, ataxia, vomiting).
Therapeutic Range
- The therapeutic range is typically 0.6-1.2 mmol/L, with lower targets (0.4-0.8 mmol/L) often used for maintenance therapy.
- Blood samples should be drawn 12 hours after the last dose for accurate trough levels.
Potential Toxicity
- Lithium has a narrow therapeutic window, and levels above 1.5 mmol/L can cause toxicity, while levels exceeding 2.0 mmol/L constitute a medical emergency requiring immediate intervention.
- Regular monitoring of GFR, electrolytes, and drug levels is recommended for people taking potentially nephrotoxic agents such as lithium, as stated in 1.
From the FDA Drug Label
Blood samples for serum lithium determination should be drawn immediately prior to the next dose when lithium concentrations are relatively stable (i.e., 8-12 hours after the next dose). Serum levels should be determined twice per week during the acute phase, and until the serum level and clinical condition of the patient have been stabilized. Serum lithium levels in uncomplicated cases receiving maintenance therapy during remission should be monitored at least every two months.
Blood tests for patients on lithium should be done:
- Immediately prior to the next dose, when lithium concentrations are relatively stable (8-12 hours after the previous dose) 3
- Twice a week during the acute phase, until the serum level and clinical condition are stabilized 3
- At least every two months for patients on maintenance therapy during remission 3
From the Research
Blood Tests for Patients on Lithium
- Regular monitoring of kidney function is crucial for patients taking lithium, as it can affect kidney function and increase the risk of chronic kidney disease 4, 5.
- Blood tests for patients on lithium typically include: + Serum creatinine concentration to estimate glomerular filtration rate (GFR) 4, 5. + Estimated glomerular filtration rate (eGFR) to assess kidney function 5, 6. + Urea and electrolyte tests to monitor overall kidney function 6. + Lithium blood levels to ensure therapeutic levels and prevent toxicity 7.
- Monitoring lithium blood levels is essential to ensure efficacy and patient safety, as lithium has a narrow therapeutic index and significant drug interactions 7.
- Demographic characteristics such as age and gender, as well as possible drug interactions, can affect lithium blood levels 7.
- Regular monitoring of eGFR and lithium blood levels can help prevent chronic kidney disease and ensure safe and effective use of lithium 4, 5, 6, 7.
Note
- One study 8 is not relevant to the question of blood tests for patients on lithium, as it discusses the genome expression of positive-stranded RNA viruses.