From the Guidelines
Yearly lithium monitoring requires essential laboratory tests, including serum lithium levels, kidney function tests (creatinine, BUN, eGFR), thyroid function tests (TSH, free T4), electrolytes (particularly sodium), and a complete blood count (CBC), as well as serum calcium levels, to ensure safe and effective treatment. These tests are crucial because lithium has a narrow therapeutic window and can affect multiple organ systems, as noted in the guidelines for monitoring patients on lithium therapy 1. Kidney monitoring is particularly important as lithium can cause nephrogenic diabetes insipidus and chronic kidney disease with long-term use, and it is recommended to monitor GFR, electrolytes, and lithium levels regularly, at least every 6 months or more frequently if the dose changes or the patient is acutely unwell 1. Thyroid function requires monitoring because lithium can induce hypothyroidism. Electrolyte imbalances, especially hyponatremia, can increase lithium toxicity risk. More frequent monitoring may be needed for patients with unstable lithium levels, medication changes, illness, or signs of toxicity. The most recent and highest quality study recommends regular monitoring of these parameters to minimize the risk of adverse effects and ensure optimal treatment outcomes 1.
Some key points to consider in lithium monitoring include:
- Serum lithium levels should be maintained within the therapeutic range of 0.6-1.2 mEq/L, with the specific target depending on the condition being treated and individual response.
- Kidney function tests, including creatinine, BUN, and eGFR, should be monitored regularly to detect any potential nephrotoxic effects of lithium.
- Thyroid function tests, including TSH and free T4, should be monitored to detect any potential effects of lithium on thyroid function.
- Electrolyte levels, particularly sodium, should be monitored to detect any potential imbalances that could increase the risk of lithium toxicity.
- A complete blood count (CBC) should be monitored to detect any potential effects of lithium on blood cell production.
- Serum calcium levels should also be checked, as lithium can affect calcium metabolism.
Overall, regular monitoring of these laboratory tests is essential to ensure safe and effective treatment with lithium, and to minimize the risk of adverse effects.
From the FDA Drug Label
Serum lithium levels in uncomplicated cases receiving maintenance therapy during remission should be monitored at least every two months. The required labs for yearly lithium monitoring are not explicitly stated, but serum lithium levels should be monitored at least every two months.
- Serum creatinine or creatinine clearance may be used to evaluate glomerular function.
- Urinalysis and other tests, such as urine specific gravity or osmolality, may be used to evaluate tubular function. 2 2
From the Research
Yearly Lithium Monitoring Labs
The following labs are required for yearly lithium monitoring:
- Serum lithium levels: to check the level of lithium in the blood 3
- Serum creatinine: to monitor renal function 4, 5, 6, 7
- Estimated glomerular filtration rate (eGFR): to assess kidney function 5, 6, 7
- Thyroid-stimulating hormone (TSH) monitoring: as lithium can affect thyroid function 4
- Calcium testing: as lithium can affect calcium levels 4
- Urine tests: such as urine osmolality, specific gravity, and urine albumin measurement to monitor kidney function and detect potential kidney damage 6, 7
- Blood urea nitrogen (BUN) and urinalysis: to monitor renal function and detect potential kidney damage 6
Frequency of Monitoring
The frequency of monitoring may vary depending on the individual patient's needs and circumstances:
- Serum lithium levels: every 3 months for patients with stable levels, but can be extended to 6 months for patients who have achieved 12 months of stable levels within the target range 3
- Renal function tests: every 3 months for patients with decreased renal function or other risk factors, but can be done less frequently for patients with normal renal function 4, 5, 6, 7