From the Guidelines
For patients on lithium therapy, regular monitoring should include serum lithium levels, renal function tests, thyroid function tests, electrolytes, and a complete blood count, with the frequency of monitoring depending on the patient's condition and stability of therapy, as recommended by the most recent guidelines 1.
Monitoring Requirements
The monitoring requirements for patients on lithium therapy include:
- Serum lithium levels, which should be checked 5-7 days after dose changes and every 3-6 months during stable therapy, with target therapeutic ranges typically between 0.6-1.2 mEq/L depending on the condition being treated 1
- Renal function tests, including creatinine, BUN, and eGFR, which should be assessed before starting lithium and then every 6-12 months, as lithium can cause nephrotoxicity with long-term use 1
- Thyroid function tests, including TSH and free T4, which should be assessed before starting lithium and then every 6-12 months, as lithium can cause hypothyroidism with long-term use 1
- Electrolytes, particularly sodium, which should be monitored because hyponatremia can increase lithium levels and toxicity risk 1
- Complete blood count, which should be monitored regularly to detect any potential hematological abnormalities 1
Special Considerations
More frequent monitoring is necessary for:
- Elderly patients
- Those with medical comorbidities
- During situations that might alter lithium levels, such as acute illness, dehydration, or medication changes that interact with lithium 1 Patients should have lithium levels drawn 12 hours after the last dose (trough level) for accurate interpretation 1.
Clinical Implications
The monitoring of patients on lithium therapy is crucial to minimize the risk of adverse effects, such as nephrotoxicity and hypothyroidism, and to ensure the optimal therapeutic effect of the medication 1.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Acute Mania: ... 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. Long-term Control: ... Serum lithium levels in uncomplicated cases receiving maintenance therapy during remission should be monitored at least every two months.
The recommended laboratory tests for monitoring patients on lithium therapy are:
- Serum lithium levels:
- During the acute phase, serum levels should be determined twice per week
- For long-term control, serum levels should be monitored at least every two months 2
From the Research
Laboratory Tests for Monitoring Patients on Lithium Therapy
- Lithium serum levels should be monitored on a regular basis, with varying target ranges 3
- Renal and thyroid function should be monitored before start and during maintenance treatment, with almost all prescribers (> 97%) reporting to do so 3
- Monitoring of other laboratory and physical parameters is variable, with the majority of respondents (74%) using guidelines or institutional protocols for monitoring 3
- Clinical guidelines recommend checks of renal and thyroid function before lithium is prescribed, and that all patients who are prescribed lithium should have their renal and thyroid function checked every six months, and their serum lithium checked every three months 4
- The quality of lithium monitoring in patients who are in contact with mental health services falls short of recognised standards and targets, with only 30%, 55%, and 50% of patients meeting the NICE standards for monitoring lithium serum levels, and renal and thyroid function, respectively 4
Recommended Monitoring Intervals
- Serum lithium levels should be checked every three months 4, 5
- Renal and thyroid function should be checked every six months 4, 6
- Thyroid-stimulating hormone (TSH) monitoring is recommended, with a peak interval at 3 months suggesting that thyroid function is frequently checked at the same time as serum lithium 6
Adherence to Monitoring Guidelines
- Adherence to recommended monitoring intervals is poor, with only 24.1%, 42.4%, and 66.8% of lithium users having at least one serum lithium concentration recorded within 90,180, and 365 days of follow-up, respectively 5
- Infrequent and inconsistent monitoring of lithium levels and renal function is common in geriatric patients, with absolute differences between lithium and valproate users not being clinically meaningful 5