Dr. Greene's Answer
Each meal is a matter of life and death for children with propionic acidemia. Children need protein in order to grow and thrive, but for these children extra protein is a deadly poison.
Here’s the problem: The amount they need to grow is a little more than the amount they can handle. Each meal becomes a delicate balancing act that can make the difference between normal development and long-term disability.
Breastfeeding with Propionic Acidemia
Knowing that your baby has this precarious illness must make the desire to nurse and comfort your baby even stronger. But, as cruel as it seems, even breastmilk can be dangerous, unless it is used in just the right way.
Propionic acidemia is one of what we call the inborn errors of metabolism. The individual metabolic disorders are rare, but taken as a group they are fairly common. I do know women who have nursed successfully with metabolic disorders. Some of the metabolic disorders make nursing difficult but still a great benefit.1 Others make nursing harmful.2
Normally, when we eat protein in our food, our enzymes break the protein down into molecular building blocks. We then reassemble these into the specific protein molecules and other substances our bodies need. Proteins are made up of amino acids.
In propionic acidemia, one little enzyme is missing, but this is enough to change an entire life. Without the enzyme propionyl CoA carboxylase, some common amino acids in protein (isoleucine, valine, threonine, and methionine), are only partially processed. One of the intermediate stages, propionic acid, builds up in the bloodstream.
The propionic acid causes poor feeding, vomiting, dehydration, floppiness, and lethargy, which usually show up in the first weeks of life, and can progress rapidly to coma and death. Seizures occur in about 1/3 of babies. If a baby survives the first attack, similar episodes may occur during an unrelated infection, constipation, or following a high-protein meal.
Some children sail through the early months without apparent problem and don’t come to attention until much later in life.
Before it was recognized and treated, propionic acidemia was usually fatal. With right treatment, it is possible for children to grow and develop normally. The right treatment is crucial. It greatly improves children’s odds but is not the whole story.
Some children are treated perfectly and still have bad outcomes. Others receive no treatment at all and thrive. Even within the same family, there can be wide variability of this disease. One boy was first diagnosed at age 5 because of mental retardation; his 13-year-old sister turned out to have the same level of enzyme deficiency but had no symptoms at all!3
The cornerstone of treatment is to restrict protein. Other measures can be helpful (supplementing with L-carnitine, supplementing with thiamine,4 using antibiotics to kill gut bacteria that produce amino acids, using alkaline treatment to decrease acid, treating any constipation immediately, etc), but without restricting protein, none of the other treatments help.
Generally with the low-protein diet, regular protein must be restricted to 1.0-1.5 g/kg per 24 hours. To get enough protein to grow and thrive, kids can supplement this with specially made proteins without isoleucine, valine, methionine, and threonine. This allows the total protein to be increased to 1.5-2.0 g/kg per 24 hours.5 The baby needs to be carefully monitored, especially during times of stress or infection, to achieve just the right balance of protein.
Is Breastfeeding with Propionic Acidemia Possible?
I was not aware of anyone who had breastfed successfully with propionic acidemia, so I contacted Iraj Rezani, M.D., the Chief of the Section of Metabolic Disorders at the Temple University Children’s Medical Center and the author of the leading pediatric text on propionic acidemia. He explained that the act of nursing is impossible, even once a day, because the concentration of protein in human milk (1.5%) is just too high-even in small amounts. In those few precious days after a baby is born and before a mom’s milk comes in, the concentration of protein is even higher in the little bit of colostrum that appears. Breastmilk must be pumped, diluted, and carefully measured to be safely used.
In the past few years, researchers at the Istanbul Medical Faculty in Istanbul, Turkey, have studied the possibility of safely breastfeeding children with inborn errors of metabolism. Unfortunately, to date, only one child with propionic acidemia was included in their studies. During three months of breastfeeding, that child had two metabolic emergencies and was quickly switched to a low-protein formula. (Journal of Inherited Metabolic Disease. 28(4):457-65, 2005.)
Ross Labs (with whom I have no affiliation) has designed a comprehensive line of medical foods designed to meet nutrition needs in people with this and other inborn errors of metabolism (more than 3 dozen in all). I applaud them for addressing the needs of families with these rare conditions. Propimex-1 is a ready-to-feed formula for infants and toddlers. Propimex-2 is designed for children and adults with propionic acidemia.
What’s on the Horizon?
I am hopeful that, in your baby’s lifetime, gene therapy will be able to replace the missing enzyme. For now, liver transplantation is the most effective way to do this.7 But unless and until your child has the enzyme replaced, the propionic acidemia diet should be followed carefully.
I feel for the poignancy of your situation. Because your baby was diagnosed before birth, I suspect there may have been another baby in your family who died. How hard this time must be for you!
I am a huge fan of nursing, but I am also confident that the love you already feel will surround and caress and comfort and nourish your baby. When people are denied their eyesight, their other senses become more powerful. I observe that when people who want to nurse are denied the opportunity, all of the other ways of bonding give rise to unexpected levels of closeness.
1 Position of the American Dietetic Association: promotion of breast-feeding- J Am Diet Assoc – 1997 Jun; 97(6): 662-6
2 Lawrence RM – Given the benefits of breastfeeding, what contraindications exist?- Pediatr Clin North Am – 01-Feb-2001; 48(1): 235-51
3 Nelson Textbook of Pediatrics – 16th edition. WB Saunders 2000
4 Matern D – Primary treatment of propionic acidemia complicated by acute thiamine deficiency. – J Pediatr – 1996 Nov; 129(5): 758-60
5 Nelson Textbook of Pediatrics – 16th edition. WB Saunders 2000
6 Feillet F – Resting energy expenditure in disorders of propionate metabolism. – J Pediatr – 2000 May; 136(5): 659-63
7 Yorifuji et al.- Living-related liver transplantation for neonatal-onset propionic acidemia – J Pediatr 2000 Oct; 137(4).