Breast milk jaundice - a review

Serum bilirubin estimation, which has for some years now been available on point-of-care analyzers, including blood gas analyzers, is probably the most frequently requested blood test in neonatal medicine. 

This is because increased serum/plasma bilirubin concentration (hyperbilirubinemia) and consequent jaundice is very common during the neonatal period with close to half of all newborns becoming jaundiced during the first weeks of life. 

There are a number of causes, both physiological and pathological, for neonatal jaundice, and a recently published review article focuses on one of the most common causes: breast milk feeding. According to US data referenced in this review, a third of all babies who are exclusively breastfed develop breast milk jaundice during the first 2-3 weeks of life. 

Although the condition is benign in the sense that jaundice is mild (serum bilirubin does not exceed 200 µmol/L [12 mg/dL]) and self-limiting (resolves without treatment within 12 weeks), it poses a clinical problem because it must be identified and distinguished from more serious pathological causes of jaundice. 

Providing solution of this particular clinical problem is the raison d’etre of the article, but it is more wide-ranging in terms of the topics discussed. These include first, by way of introduction, the distinction between total, unconjugated and conjugated bilirubin, along with a brief overview of neonatal bilirubin metabolism and the cause of physiological jaundice. 

There follows a discussion of precisely when and why breast milk jaundice occurs. The authors make clear the sometimes confused distinction between jaundice caused by breast milk feeding and jaundiced caused by inadequate breast milk feeding. 

They helpfully refer to the two quite separate clinical entities as ”breast milk jaundice” and “not enough breast milk jaundice”; the second is clinically distinguished from the first by evidence of poor nutrition (low urine/stool output, failure to clear meconium and poor or absent weight gain). 

The article goes on to consider the pathological causes of jaundice that might be confused with, or co-exist with, breast milk jaundice. A diagnosis of breast milk jaundice can only be made by exclusion of all other causes of jaundice and the authors provide a valuable algorithm that can be used to direct this process of exclusion. 

They emphasize that breast milk jaundice is an entirely benign condition that ideally should not provoke withdrawal of breast milk and institution of formula feeding. In some diagnostically difficult cases of neonatal jaundice, however, temporary withdrawal of breast milk can be diagnostically helpful. Although the principal focus of this review is breast milk jaundice, it provides a useful overview of neonatal jaundice generally.