Fluorescein Concentrations in Human Breast Milk

In the past few months there have been discussions — online and elsewhere — regarding fluorescein elimination in breast milk and recommendations for lactating patients undergoing fluorescein angiography. The desire to perform fluorescein angiography on postpartum women raised concerns regarding safety to the nursing infant and it was unknown if women should refrain from nursing following fluorescein injection. Life-threatening phototoxicity secondary to fluorescein administration has been described in a premature infant. In 1991, we conducted a study to ascertain the concentration of fluorescein eliminated in breast milk over an extended period of time. The results of this study were presented that year at the Association for Research in Vision and Ophthalmology (ARVO). The study was performed on a woman who was 8 months postpartum. Nursing was curtailed for the first 8 hours of the study. The woman received 5 cc of 10% fluorescein sodium intravenously. Bilateral simultaneous electric pump expression of breast milk with complete emptying at each time point was performed at 1, 2, 4, 8, 30, 96, and 120 hours after fluorescein administration. Each sample was dated and stored in individual containers in a below zero degree Celsius freezer. Fluorescein concentrations in breast milk samples were determined using a scanning fluorophotometer with a sensitivity of 1 ng/ml. The concentration of fluorescein measured in the breast milk specimens ranged from a peak concentration of 8826 ng/ml in the earliest sample to 391 ng/ml. The half-life of fluorescein elimination in breast milk was approximately 3 hours. Our results demonstrated the early appearance of fluorescein in breast milk one hour after intravenous administration and prolonged elimination with readily detectable levels 5 days after injection. Without measuring the concentration of fluorescein in the blood or urine of a nursing infant, it is difficult to determine the actual amount of absorption by the infant. The impaired hepatic and renal function in a premature infant could lead to a cumulative dose of fluorescein from breast milk which may approach toxic concentrations. Based on our results, it seems prudent that lactating women undergoing intravenous fluorescein administration should be advised to refrain from nursing for at least 8-12 hours post-injection and possibly for longer periods with premature infants. If the fluorescein angiogram can be safely delayed, an adequate supply of breast milk could be expressed and stored for post-angiogram feedings. For information regarding proper storage of breast milk, access www.aap.org or www.breastfeeding.net* for the American Academy of Pediatrics web site.