Lithium & Kidney Stones

When patients who take lithium develop kidney stones, they may wonder whether their medication is the cause. Some doctors believe lithium doesn't cause kidney stones, but lithium is known to have other effects on the kidneys.

Lithium is often used as a mood-stabilizing drug for conditions such as bipolar disorder. Patients taking lithium must have their blood chemistry tested regularly because serious side effects from the drug can occur.

Lithium Chemistry and Kidney Stones

• Lithium's first use as a drug, in 1859, was actually a treatment for gout and kidney stones. Uric acid crystals are the cause of gout and one type of kidney stone. When lithium meets uric acid crystals, it can dissolve them. Doctors had to abandon this treatment when they discovered that the doses of lithium that could dissolve the crystals were so high that they caused lithium poisoning.

Toxicity in the Body

• Lithium can be toxic, and an estimated 10,000 cases of lithium toxicity occur per year in the United States. Chronic toxicity (caused by taking normal or slightly large doses of lithium over a long period of time) can include several types of kidney damage. Because lithium interferes with the body's natural anti-diuretic hormone, it can impair water re-absorption, causing the body to excrete too much water.

  Other kidney disorders caused by lithium include chronic tubulointerstitial nephritis, nephrotic syndrome and distal renal tubular acidosis.

Possible Causes

• Distal renal tubular acidosis, a known effect of chronic lithium toxicity, interferes with the kidney's ability to collect acids into the urine. The result is that the blood is too acidic. Having too much acid in the bloodstream can cause bone diseases, other kidney diseases and kidney stones. This may be why people who take lithium for a long time can develop kidney stones.

Prevention

• When someone takes lithium, his doctor should check blood levels of lithium regularly. Blood levels from 0.6 to 1.2mmol/L are recommended for proper treatment. A doctor should determine the lowest dose of lithium that treats symptoms because higher levels carry more risks for kidney damage.

  The doctor also should check kidney function regularly to ensure they work properly. She should work with a nephrologist if possible, according to Dr. James W. Jefferson, a professor of psychiatry at the University of Wisconsin, Madison, cited in a "Clinical Psychiatry News" 2002 article.

Alternatives to Lithium

• Anti-seizure medications, such as Tegretol and Depakote, also can be used to treat bipolar disorder and may be an effective alternative treatment to lithium. A patient taking lithium may speak with her doctor about taking these or other medications instead of lithium.