Can lithium cause hypertension?

Lithium and Hypertension: Clinical Implications

Lithium can cause hypertension as it is specifically listed as a substance that may alter blood pressure in clinical guidelines. 1

Mechanism and Evidence

Lithium is identified in the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure as one of the chemical elements that can affect blood pressure 1. The 2020 International Society of Hypertension Global Hypertension Practice Guidelines also recognize various medications and substances, including mood stabilizers like lithium, as potential exacerbators of hypertension 1.

While the exact mechanism by which lithium may increase blood pressure is not fully elucidated in the guidelines, there are several important clinical considerations:

• Lithium salts are specifically mentioned among chemical elements that can alter blood pressure 1
• Lithium appears on lists of substances that clinicians should screen for in patients with hypertension or at risk for hypertension 1
• Monitoring is essential as lithium has a narrow therapeutic index, with target serum levels of 0.6-0.8 mmol/L for standard formulations 2

Clinical Monitoring and Management

When prescribing lithium, healthcare providers should:

• Screen for hypertension before initiating therapy
• Monitor blood pressure regularly during treatment
• Consider potential interactions with antihypertensive medications, particularly diuretics and renin-angiotensin system inhibitors, which can lead to lithium toxicity 3
• Be aware that the introduction of antihypertensive drugs in patients on lithium requires careful monitoring of serum lithium levels 3

Special Considerations

Medication Interactions

Particular caution is needed when combining lithium with antihypertensive medications:

• A regression analysis showed that the severity of lithium intoxication was significantly predicted by use of certain classes of antihypertensive agents 3
• Diuretics and inhibitors of the renin-angiotensin system may increase risk of lithium toxicity 3

Monitoring Requirements

Regular monitoring is essential:

• Serum lithium levels should be monitored twice weekly until stabilized in the acute phase, and every 2-3 months in the maintenance phase 2
• Blood pressure should be monitored regularly, especially after initiating treatment or changing dosages
• Renal function, thyroid function, and electrolytes should be monitored every 3-6 months 2

Contradictory Evidence

Interestingly, some animal studies show contradictory effects:

• Research in spontaneously hypertensive rats found that chronic lithium treatment actually decreased blood pressure by approximately 15-30 mmHg 4, 5
• However, there is also a case report of pulmonary hypertension developing in a patient during lithium therapy 6

These contradictory findings highlight the complex relationship between lithium and blood pressure regulation, and underscore the importance of individualized monitoring in clinical practice.

Clinical Approach

1. Before starting lithium:

   • Obtain baseline blood pressure measurements
   • Assess cardiovascular risk factors
   • Consider alternative mood stabilizers in patients with poorly controlled hypertension

2. During lithium treatment:

   • Monitor blood pressure at regular intervals
   • Watch for signs of hypertension, especially when lithium doses are adjusted
   • Be vigilant about potential interactions with antihypertensive medications

3. If hypertension develops:

   • Consider whether lithium is contributing to blood pressure elevation
   • Weigh risks and benefits of continuing lithium versus switching to an alternative mood stabilizer
   • If lithium must be continued, optimize antihypertensive therapy while monitoring for interactions

Remember that while lithium is identified as a potential cause of hypertension in clinical guidelines, the clinical significance may vary between individuals, and the benefits of lithium therapy for mood disorders may outweigh this risk in many patients.