The best questions often stem from the inquisitive learner. As educators, we love—and are always humbled by—those moments when we get to say, “I don’t know.”  For some of these questions, you may already know the answers. For others, you may never have thought to ask the question. For all, questions, comments, concerns, and critiques are encouraged. Welcome to the Kids Korner.

In a young infant with easy bleeding or bruising, how long do we really need to consider vitamin K-dependent bleeding (VKDB) on the differential?

There are several diagnoses on the differential when thinking of easy bleeding or bruising in young infants. Close to the top of the list are hemophilia, an acquired bleeding disorder, and non-accidental trauma (i.e., child abuse). But what about VKDB? How long does that really last? How long do we need to consider that as a cause of easy bleeding or bruising in infants? 

Considering VKDB

Vitamin K is a fat-soluble vitamin required by the liver in the synthesis of factors II, VII, IX, and X. Vitamin K poorly transfers across the placenta, and newborn infants have insufficient vitamin K stores. Additionally, there are very low concentrations of vitamin K in human milk.¹ A nursing baby has little to start and gets little when nursing, and as a result, can have significantly low levels of factors II, VII, IX, and X. Basically, think of VKDB as warfarin for babies. In the United States, newborns commonly get vitamin K supplementation as an intramuscular injection shortly after birth. Oral formulations also exist but are less common.

VKDB is typically divided into three groups: early, classic, and late. Early VKDB occurs within the first 24 hours of life in newborns born to mothers taking medications that cross the placenta and inhibit vitamin K activity.^1,2 Classic VKDB occurs between days two to seven of life and is usually idiopathic. Late VKDB begins at day eight of life and results from severe vitamin K deficiency primarily in breast-fed infants where vitamin K is poorly transmitted in breast milk. But how long do we need to consider this entity? What about the 3-month-old child with bruising?  What about the 6-month-old child with bruising? 

One study evaluated 120 cases of late VKDB in infants from Turkey from 1990-2006.¹ Of these 120 patients, 83 were boys and 37 were girls. The timing (by days) of late VKDB was days eight to 14 (6 percent); days 15-30 (21 percent); days 31-45 (36 percent); days 61-90 (11 percent); and days 91-240 (9 percent). The study does not specifically mention the case with the latest onset of VKDB, so we are only able to really gather that it occurred at least up to 91 days (about three months).