From the Guidelines
Patients taking lithium should maintain consistent salt (sodium) consumption in their diet to avoid potential toxicity or reduced effectiveness of the medication. This is crucial because changes in sodium levels can affect lithium levels in the blood, as both are handled similarly by the kidneys 1. Decreasing salt intake can cause lithium levels to rise, potentially leading to toxicity, while suddenly increasing salt consumption can lower lithium effectiveness. For those on lithium therapy, typically prescribed at doses of 600-1200mg daily for bipolar disorder, it's essential to avoid dramatic changes in salt intake, stay well-hydrated, and have regular blood tests to monitor lithium levels.
Some key points to consider:
- The relationship between lithium and sodium is critical, and patients should be aware of the potential risks of changing their salt intake while on lithium therapy.
- Regular monitoring of lithium levels, electrolytes, and kidney function is recommended for patients taking lithium, as suggested by the 2014 guideline 1.
- Reducing sodium intake can be beneficial for overall health, but it's crucial to do so gradually to avoid potential complications, especially in patients with specific medical conditions or those taking certain medications.
- Potassium-enriched salt substitutes may be a useful option for reducing sodium intake, but their use should be approached with caution, particularly in patients with advanced kidney disease or those using potassium supplements or potassium-sparing diuretics, as highlighted in a recent review 1.
In terms of specific recommendations, patients on lithium therapy should aim to maintain a consistent sodium intake and avoid sudden changes. The ideal sodium intake may vary depending on individual factors, but general guidelines suggest limiting daily sodium intake to less than 2,000 mg (87 mmol) per day, as recommended by the Cardiovascular and Adequacy Guidelines 1. However, the most recent and highest-quality study on this topic, published in 2024, suggests that potassium-enriched salt substitutes may be a useful option for reducing sodium intake and improving cardiovascular health, but their use should be tailored to individual patient needs and medical conditions 1.
From the FDA Drug Label
Lithium decreases sodium reabsorption by the renal tubules which could lead to sodium depletion. Therefore, it is essential for the patient to maintain a normal diet, including salt, and an adequate fluid intake (2500-3000 mL) at least during the initial stabilization period Decreased tolerance to lithium has been reported to ensue from protracted sweating or diarrhea and, if such occur, supplemental fluid and salt should be administered.
Lithium decreases sodium reabsorption, which could lead to sodium depletion. To prevent this, patients should maintain a normal diet, including salt, and adequate fluid intake. If sweating or diarrhea occur, supplemental fluid and salt should be administered 2.
From the Research
Lithium and Salt Interaction
- There is no direct evidence of an interaction between lithium and salt in the provided studies 3, 4, 5, 6, 7.
- However, lithium treatment has been associated with kidney function decline, which may be related to its effects on the kidneys rather than a direct interaction with salt 5, 6, 7.
- Lithium-induced nephropathy is a known complication of long-term lithium treatment, and it can lead to end-stage renal disease in some patients 3, 6.
- The risk of kidney function decline associated with lithium treatment can be predicted using a model that includes age, sex, and baseline estimated glomerular filtration rate (eGFR) 4.
- Patients with bipolar disorder or schizoaffective disorder who are treated with lithium may experience a faster decline in eGFR compared to the general population, and this decline can be attributed to lithium treatment 5.
- Monitoring of kidney function is necessary for patients on long-term lithium therapy, and discontinuation of lithium should be considered in case of detecting nephropathy 6.
- Lithium serum level thresholds associated with thyroid and kidney abnormalities have been identified, and these thresholds may facilitate the development of evidence-based guidelines for lithium treatment 7.