What is the interaction between Lithium and Calcium supplements?

From the Guidelines

Lithium and calcium supplements should be taken separately to avoid potential interactions, with a minimum of 2 hours apart, to minimize the risk of calcium interfering with lithium absorption and to prevent adverse effects on bone health and kidney function. For lithium, which is used to treat bipolar disorder, typical dosages range from 600-1200mg daily, divided into multiple doses, with blood levels monitored regularly (therapeutic range: 0.6-1.2 mEq/L) 1. Calcium supplements, commonly taken for bone health, are usually dosed at 1000-1200mg daily for adults. It is essential to note that calcium supplements may reduce the risk of fracture, but high-quality trials with low risk of bias have shown no effect of supplementation on the risk of fracture at any site 1. Lithium is typically taken with food to reduce gastrointestinal side effects, while calcium carbonate is best absorbed with food and calcium citrate can be taken without food. Patients should maintain consistent salt and fluid intake while on lithium to prevent fluctuations in blood levels. Both supplements require medical supervision - lithium due to its narrow therapeutic window and potential toxicity, and calcium because excessive supplementation can lead to hypercalcemia and kidney stones, as well as an increased risk of myocardial infarction 1. Always consult a healthcare provider before starting either supplement, especially if you're taking other medications.

Some key considerations for patients taking lithium and calcium supplements include:

• Monitoring blood levels of lithium and calcium regularly
• Maintaining consistent salt and fluid intake
• Taking supplements at least 2 hours apart
• Being aware of the potential risks of hypercalcemia, kidney stones, and myocardial infarction
• Consulting a healthcare provider before starting or stopping either supplement
• Considering the potential benefits and risks of calcium supplementation on bone health, as high-quality trials have shown mixed results 1, 2.

In terms of specific guidance, patients with bipolar disorder taking lithium should be cautious when taking calcium supplements, as the interaction between the two may affect lithium absorption and increase the risk of adverse effects 1. Additionally, patients with a history of kidney disease or osteoporosis should be closely monitored when taking calcium supplements, as excessive supplementation can exacerbate these conditions 2.

From the Research

Interaction between Lithium and Calcium Supplements

• The interaction between lithium and calcium supplements is complex, with lithium affecting calcium and parathyroid hormone (PTH) homeostasis 3, 4, 5.
• Lithium stimulates the proliferation of parathyroid cells, leading to an increase in serum calcium and PTH levels, and a 4 to 6-fold higher risk of primary hyperparathyroidism than in the general population 3.
• The prevalence of hypercalcaemia is significantly higher in lithium-exposed patients, with 24.1% of patients experiencing hypercalcaemia 4.
• Lithium-associated hyperparathyroidism and hypercalcaemia can be managed through regular monitoring of calcium and PTH levels, and referral to an endocrinologist if necessary 5.
• Long-term lithium treatment is associated with a range of side effects, including reduced urinary concentrating ability, nephrogenic diabetes insipidus, and increased risk of renal failure and hypothyroidism 6.
• Periodic monitoring of serum calcium levels is recommended in patients on long-term lithium therapy, and surgical removal of the affected parathyroid gland may be necessary in cases of resistant hypercalcaemia and parathyroid adenoma 7.

Key Findings

• Lithium increases serum calcium and PTH levels, leading to a higher risk of primary hyperparathyroidism 3, 4.
• Regular monitoring of calcium and PTH levels is necessary to manage lithium-associated hyperparathyroidism and hypercalcaemia 5.
• Long-term lithium treatment is associated with a range of side effects, including renal, endocrine, and dermatological effects 6.
• Surgical removal of the affected parathyroid gland may be necessary in cases of resistant hypercalcaemia and parathyroid adenoma 7.

Clinical Implications

• Clinicians should be aware of the potential side effects of long-term lithium treatment, including lithium-associated hyperparathyroidism and hypercalcaemia 3, 4, 5, 6, 7.
• Regular monitoring of calcium and PTH levels is necessary to manage lithium-associated hyperparathyroidism and hypercalcaemia 5.
• Referral to an endocrinologist may be necessary in cases of resistant hypercalcaemia and parathyroid adenoma 5, 7.