What is the best course of action to manage a patient's persistent impulsivity and irritability with a subtherapeutic lithium level of 0.5 mmol?

From the Guidelines

The best course of action for managing persistent impulsivity and irritability with a subtherapeutic lithium level of 0.5 mmol/L is to gradually increase the lithium dose to achieve a therapeutic level between 0.6-1.2 mmol/L. I recommend increasing the daily lithium dose by 150-300mg increments, with follow-up serum level testing after 5-7 days at each new dose until reaching the therapeutic range, as the patient is already taking a high dose of 1350mg daily 1. The target should initially be 0.8-1.0 mmol/L, with blood draws taken 12 hours after the last dose. During titration, monitor for side effects such as tremor, nausea, diarrhea, and polyuria. Regular kidney function, thyroid function, and electrolyte tests should be performed every 3-6 months once stabilized. If the patient cannot tolerate lithium or fails to respond adequately at therapeutic levels, consider adding or switching to alternative mood stabilizers such as valproate (starting at 250mg twice daily) or carbamazepine (starting at 200mg twice daily) 1. Key considerations in this patient's management include:

• Monitoring for signs of lithium toxicity, such as confusion, ataxia, or seizures
• Adjusting the dose based on serum levels and clinical response
• Educating the patient on the importance of consistent dosing and follow-up appointments
• Considering the potential impact of the patient's night shift work and busy schedule on their sleep patterns and mood stability, and exploring strategies to improve sleep hygiene and reduce stress. Lithium works by modulating neurotransmitter systems and inhibiting glycogen synthase kinase-3, which helps regulate mood and reduce impulsivity, but these effects are dose-dependent and require adequate serum concentrations to be effective 1.

From the Research

Patient's Current Status

• The patient reports feeling noticeably better since the last visit, although not at 100%.
• The patient's mood is stable, but they sometimes experience impulsivity and irritability.
• The patient's sleep is poor due to working night shifts, a busy schedule, and an inability to maintain a normal sleep pattern.
• The patient is making an effort to switch to a day shift, which is showing some progress.

Medication and Lithium Levels

• The patient is consistent with taking lithium, but the current daily dose is 1350mg, which is lower than the previous dose of 1500mg.
• The last lithium level check result was 0.5 mmol, which is subtherapeutic 2.
• The patient is amenable to a lithium dosage increase, and the importance of medication adherence was discussed.

Management of Impulsivity and Irritability

• Studies suggest that lithium can be effective in managing impulsivity and irritability in patients with bipolar disorder 3, 4.
• A subtherapeutic lithium level, such as the patient's current level of 0.5 mmol, may contribute to persistent impulsivity and irritability 2, 5.
• Increasing the lithium dosage to a therapeutic level may help alleviate impulsivity and irritability, as lithium has been shown to decrease impulsivity levels by regulating serotonergic and dopaminergic systems 4.
• Other treatment options, such as carbamazepine, serotonin reuptake inhibitors, and neuroleptics, may also be considered for managing impulsivity and irritability, but lithium remains a major option in the management of bipolar disorder 3, 6.

Recommendations

• Consider increasing the patient's lithium dosage to a therapeutic level, as the current level of 0.5 mmol is subtherapeutic 2.
• Monitor the patient's lithium levels regularly to ensure they are within the therapeutic range and adjust the dosage as needed 2.
• Continue to assess the patient's impulsivity and irritability, and consider additional treatment options if symptoms persist despite optimal lithium levels 3, 4, 6.