From the Guidelines
Lithium monitoring should include baseline labs such as complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid stimulating hormone (TSH), urinalysis, and pregnancy test for women of childbearing potential, with subsequent monitoring of serum lithium levels, renal function, electrolytes, and thyroid function every 3-6 months. When initiating lithium therapy, it is essential to consider the potential risks and benefits, particularly in patients with pre-existing kidney disease or other comorbidities. According to the 2014 study 1, lithium can cause renal tubular dysfunction with prolonged use, even at therapeutic levels, and therefore, monitoring of GFR, electrolytes, and lithium levels is crucial.
Key Monitoring Parameters
- Serum lithium levels: should be checked after 5-7 days, then weekly until stable, and every 3-6 months thereafter
- Renal function: creatinine, BUN, and GFR should be monitored every 3-6 months
- Electrolytes: should be monitored every 3-6 months
- Thyroid function: TSH and free thyroxine (FT4) levels should be monitored every 3-6 months
- Urinalysis: should be performed every 3-6 months to monitor for signs of renal toxicity It is also important to note that more frequent monitoring is needed for dose changes, medication interactions, or signs of toxicity, as lithium has a narrow therapeutic window and can affect kidney function and thyroid hormone production over time 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION ... Regular monitoring of the patient’s clinical state and of serum lithium levels is necessary. 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 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 previous dose). To monitor lithium levels, order the following lab:
- Serum lithium level 2
From the Research
Laboratory Tests for Lithium Monitoring
To monitor lithium levels and potential side effects, the following laboratory tests are recommended:
- Serum creatinine concentration: Although it can be influenced by extrarenal factors, it is still used to estimate glomerular filtration rate (GFR) 3
- Urine osmolality: This test most accurately reflects urine concentrating ability, but specific gravity is usually adequate for clinical purposes 3
- Urine albumin measurement: This test is important, but it requires greater standardization and sensitivity to maximize its potential 3
- Thyroid function tests: Including thyroid-stimulating hormone (TSH) levels, which should be monitored every 6 months 4
- Complete Blood Count (CBC): This test can be used to assess cardiovascular and metabolic diseases, and may be useful in monitoring patients taking lithium, although its direct relevance to lithium monitoring is not well established 5
Additional Considerations
It is essential to regularly monitor kidney function in patients taking lithium, as it can affect kidney function and increase the risk of kidney disease 3. Thyroid function should also be monitored regularly, as lithium can increase the risk of thyroid dysfunction 4.