Lithium in breast milk not seen worrisome

NEW YORK (Reuters Health) - Breastfeeding mothers who are taking lithium, for bipolar disorder, may pass the drug on to their infants -- but it doesn't seem likely to cause problems.

Researchers reporting in the American Journal of Psychiatry found lithium levels in nursing infants to be low and well tolerated.

Taking lithium while breastfeeding has generally been discouraged, Dr. Adele C. Viguera, of Massachusetts General Hospital, Boston, and colleagues explain. "These cautious recommendations arise from concerns that lithium may be secreted at high levels in breast milk and infants may inefficiently clear lithium, thereby increasing their risk for significant drug exposure and toxicity."

To quantify the level of lithium exposure in nursing infants, the team measured lithium concentrations in 10 mother-infant pairs.

The infants were breast-fed for an average of 4 months, and the mothers' average lithium dose was 850 milligrams per day. The average blood level of lithium in the infants' was about half the concentration measured in breast milk, which in turn was about half the level in the mothers' blood.

The mothers reported no growth or developmental delays in their infants, and the investigators found no major abnormalities in the children.

Nevertheless, "We caution that breast-feeding while taking lithium should be considered appropriate only for carefully selected women with bipolar disorder," Viguera and colleagues conclude.

Appropriate conditions include a stable maternal mood, a simple medication regimen, a healthy infant and "a collaborative pediatrician," they advise.

SOURCE: American Journal of Psychiatry, February 2007.