Case Study: Inborn Errors of Metabolism

A very big healthy term infant boy was born at home weighing 10 #8 oz. This was the second baby for his mother.  The birth was attended by a certified nurse midwife.  Part of the protocol of nurse midwives is to return to the home at approximately 24 hours post-partum to check on the mother and baby and to perform a newborn screen to test for multiple genetic disorders.  This was done and at the 24-hour visit.  Both mom and baby were doing well.  

At the follow up visit with the midwife on day of life 5, the mother expressed concern that the baby was not gaining weight.  The baby was 9 pounds 12 oz which was less than a 10% weight loss.  The rest of the exam indicated a healthy newborn who was spitting up a bit while breastfeeding well, with normal vital signs and no jaundice.  Mother reported that he continued to be alert and had voided three times so far that day.  All his meconium had passed, and he was having seedy, yellow stools.  

The midwife counseled the mother on her diet and how it may affect the baby. On day of life #7, he was still voiding and stooling normally. The baby was feeding approximately every 1 ½  to three hours but baby was spitting a lot.  The midwife made a referral to the pediatrician. 

The pediatrician discovered the weight to be 9 pounds 7 oz (>10% weigh loss).  The history the physician obtained was that the infant was eating but needed to be awakened to eat , he was very somnolent all the time with no periods of wakefulness and he was vomiting with each feed. When he was awake he was quite irritable. 

An ultrasound to rule out pyloric stenosis was normal. The baby was mildly jaundiced with somewhat dry mucous membranes.  A chemistry and urinalysis were ordered, and the baby was found to have signs of dehydration and jaundice. The baby was admitted to the hospital.

In the hospital the baby was eating and in no distress but was still lethargic and irritable had the history of vomiting and weight loss.

Vital signs on admission were a temperature of 37 C, pulse 148, respirations 48, and saturation of 97%. His weight was 8lb 13oz which was 16% down from birth weight. The soft spot was sunken but otherwise his physical examination was normal. The baby perked up and was acting better when hydrated with IV fluids. The baby continued to nurse and vomit about 50cc with each feed. He was placed in phototherapy. The plan included a bilirubin to be repeated in 8 hours and then perform an upper GI to assess the reason for vomiting.  

The following morning a message from the state lab that reported that the baby was “positive for galactosemia”.  The state lab requested a repeat screen but when they were told about the baby’s current status, they requested genetic testing to determine the exact type of GALT gene mutation in this infant who very likely has a GALT enzyme deficiency. 

The baby was switched immediately to soy formula.   Symptoms began to improve within 12 hours with a galactose-restricted diet. Within a week, the baby was back to birth weight, easily arousable and eating well with no more vomiting. 

In all states infants are screened for the most common genetic mutations that in most cases can be cared for with a simple formula change or medication. In some instances, these tests help get infant medical help before they become ill. It is crucially important that these are checked by the pediatrician, in some cases they can save a babies life or save them from neurologic catastrophe.