From the Guidelines
Therapeutic blood levels for lithium typically range from 0.6 to 1.2 mEq/L for maintenance treatment of bipolar disorder, with levels of 0.8 to 1.2 mEq/L often targeted for acute mania. When monitoring patients on lithium therapy, several additional blood tests should be regularly checked, including:
- Renal function tests (serum creatinine, BUN, eGFR)
- Electrolytes (particularly sodium)
- Thyroid function tests (TSH, free T4)
- Complete blood count These tests are essential to monitor due to the potential nephrotoxic effects of lithium, as highlighted in the 2014 American Journal of Kidney Diseases study 1. Before initiating lithium, baseline tests should include renal function, electrolytes, thyroid function, pregnancy test for women of childbearing age, and an ECG for patients over 40 or with cardiac risk factors. Monitoring frequency should be more intensive during initiation (weekly until stable levels are achieved), then typically every 3-6 months once stable, as recommended by the 2014 American Journal of Kidney Diseases study 1 and the 2007 Journal of the American Academy of Child and Adolescent Psychiatry study 1. Lithium levels should be drawn 12 hours after the last dose (trough level) for accurate interpretation. Close monitoring is essential because lithium has a narrow therapeutic index, with toxicity potentially occurring at levels above 1.5 mEq/L and serious toxicity at levels exceeding 2.0 mEq/L, as noted in the 2021 Journal of Clinical Sleep Medicine study 1. Factors that can alter lithium levels include dehydration, sodium depletion, NSAIDs, ACE inhibitors, and diuretics, which can increase lithium concentration and risk of toxicity, as mentioned in the 2014 American Journal of Kidney Diseases study 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Acute Mania: Optimal patient response to lithium carbonate usually can be established and maintained with 600 mg t.i.d.. Such doses will normally produce an effective serum lithium level ranging between 1 and 1. 5 mEq/L. Long-term Control: The desirable serum lithium levels are 0. 6 to 1.2 mEq/l.
The therapeutic blood levels for lithium are:
- 1 to 1.5 mEq/L for acute mania
- 0.6 to 1.2 mEq/L for long-term control Other chemistries that should be monitored include:
- Serum lithium levels at least every two months in patients receiving maintenance therapy during remission
- Electrolyte levels and renal function are also important to monitor, although not explicitly stated in the provided text, as lithium can affect kidney function and electrolyte balance. It is essential to note that lithium 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 2.
From the Research
Therapeutic Blood Levels for Lithium
- The therapeutic blood levels for lithium are between 0.6-1.2 mmol/L 3, 4
- Levels above 1.2 mmol/L can be toxic, while levels below 0.6 mmol/L may be subtherapeutic 3, 5
- Lithium intoxication with a serum lithium level of greater than or equal to 3.5 mEq/l is considered potentially lethal 5
Other Chemistries to be Monitored
- Thyroid function, including thyroid-stimulating hormone (TSH) levels, should be monitored every 6 months 6
- White blood cell count (WBC) should be monitored, as lithium treatment can cause an increase in WBC 7
- Serum creatinine levels should be monitored to assess kidney function, as lithium can affect kidney function 7
- Regular monitoring of these chemistries can help identify potential side effects and ensure safe and effective treatment with lithium 3, 6, 7