What is the best practice for a patient with a lithium level of 0.74, previously on lithium (lithium carbonate) 1200 mg daily, now increased to 1500 mg daily, who refuses further blood work?

Best Practice for Managing Lithium Without Blood Work Monitoring

You should strongly counsel the patient on the critical importance of blood work and document their refusal, but if they continue to refuse monitoring, you must discontinue lithium rather than continue prescribing at an increased dose without laboratory surveillance. 1, 2

The Core Problem: Lithium Cannot Be Safely Prescribed Without Monitoring

• Lithium has a black box warning stating that lithium toxicity is closely related to serum concentrations and can occur at doses close to therapeutic levels, and the accessibility of facilities to conduct prompt and accurate serum lithium determinations should be determined before initiating therapy 3, 2
• Regular monitoring of both the patient's clinical state and serum lithium concentrations is necessary for safe prescribing 3
• The narrow therapeutic range of lithium makes therapeutic monitoring the basis for optimal use and administration of this drug 4

Why This Specific Situation Is High-Risk

• You increased the dose from 1200 mg to 1500 mg (a 25% increase), which will significantly raise the serum level 4
• The patient's baseline level of 0.74 mEq/L was already subtherapeutic for most indications (therapeutic range 0.8-1.0 mEq/L for maintenance, 1.0-1.5 mEq/L for acute mania) 4, 5
• After a dose increase, monitoring frequency should increase to 1-2 weeks until both serum level and clinical condition stabilize 1
• Lithium requires 7-8 days to reach steady-state serum concentrations after any dose change 1
• Even a single lithium level >1.0 mmol/L causes an acute decline in eGFR within 3 months 6

The Monitoring Requirements You Cannot Bypass

• During dose adjustments, serum lithium levels should be checked twice per week until both the serum level and clinical condition stabilize 1
• Standard maintenance monitoring requires lithium levels every 3-6 months at minimum 1
• You also need to monitor renal function (creatinine, eGFR), thyroid function, and electrolytes at least every 6 months 1
• Without these labs, you cannot detect early nephrotoxicity (creatinine increase >30% from baseline), hypothyroidism, or hyperkalemia >5.5 mmol/L—all of which require dose adjustment or discontinuation 1

Your Algorithmic Approach

1. Document the refusal thoroughly in the medical record, including specific risks explained to the patient (toxicity, kidney damage, thyroid dysfunction, inability to adjust dose safely) 1

2. Attempt motivational interviewing to understand barriers to blood work (cost, transportation, needle phobia, time constraints) and problem-solve these barriers 1

3. If the patient continues to refuse:

   • Do NOT continue lithium at the increased dose 1, 2
   • Consider returning to the previous dose of 1200 mg only if the patient agrees to at least quarterly monitoring 1
   • If they refuse all monitoring, you must discontinue lithium and transition to an alternative mood stabilizer that doesn't require such intensive monitoring (valproate, lamotrigine, or second-generation antipsychotics) 1

4. Explain that prescribing lithium without monitoring is below the standard of care and exposes both the patient to serious harm and you to liability 3, 2

Critical Pitfalls to Avoid

• Never assume the patient is "doing fine" clinically without labs—lithium toxicity and nephrotoxicity can be insidious and asymptomatic until severe 3, 6
• Do not rely on the patient's self-report of adherence—without levels, you cannot verify they're taking the medication or assess for drug interactions 1
• Do not continue prescribing simply because the patient insists—your duty is to practice safe medicine, not to accommodate unsafe requests 1, 2
• Remember that patients taking NSAIDs, ACE inhibitors, ARBs, or thiazide diuretics require even more frequent monitoring due to drug interactions that increase lithium levels 1

The Bottom Line on Morbidity and Mortality

• Continuing lithium at an increased dose without monitoring significantly increases the risk of lithium toxicity (which can be fatal), acute kidney injury, and chronic kidney disease 3, 6
• A single exposure to lithium levels >1.0 mmol/L causes measurable renal damage within 3 months 6
• The relapse rate with subtherapeutic lithium levels (0.4-0.6 mmol/L) is 2.6 times higher than with therapeutic levels (0.8-1.0 mmol/L), but this must be balanced against the impossibility of safe dose optimization without monitoring 5
• The mortality and morbidity risk of unmonitored lithium at an increased dose exceeds the risk of switching to an alternative mood stabilizer 3, 1, 6