When Brenden was born, other families affected by X-linked myotubular myopathy (XLMTM or MTM) told me that kids like ours often needed amino acid–based formulas and that liver issues were common—an “MTM thing.”

At the time, there was so much to learn. I focused most of my energy on the respiratory (breathing) system and didn’t really understand the “why” behind the gastrointestinal and liver issues. Honestly, I didn’t even know what the liver really did. When Brenden was about a year old, his liver enzymes were normal, so I thought, Okay, no reason to worry. But everything changed when we switched his feeding formula.

His GI doctor wanted him on Pediasure because he was “too thin.” From what I had learned in the MTM community, kids often did better on plant-based proteins like Nourish or amino acid–based formulas. I also didn’t think Brenden was underweight—his thinner build was part of his diagnosis. After much debate, the doctor agreed to a 50/50 mix of Pediasure and Nourish.

I specifically asked for liver testing after the switch, since families had warned me. Once we made the change, Brenden started vomiting his Pediasure at least once a day. I was told that was “normal” and that the problem must be the Nourish, even though he never vomited that.

A few weeks later, his enzyme tests showed slightly elevated ALT levels. I brought up the possibility of it being the “MTM thing” I’d heard about, but the doctor dismissed me, saying I was “looking for something that isn’t there.”

Not long after, we took a trip with Brenden. Our nurse mistakenly gave him only Pediasure for three straight days, skipping the Nourish overnight entirely. By the time I realized, it was too late. When we got home, Brenden’s liver enzymes were very high. His ALT was in the 100–200 range. His skin turned tan, his eyes yellow: classic jaundice. Within a week, his ALT shot up to ~600, AST to ~560, and his bilirubin was 12.6. Even his mucous was yellow. We saw the top pediatric hepatologist in our area. Unlike the GI, he truly listened to my concerns and the information I brought from conversations within the MTM community. Testing showed Brenden’s PT-INR (clotting factor) was dangerously low due to a vitamin K deficiency, and he needed an emergency transfusion.

The doctor told us waiting any longer could have been catastrophic. His bile salts were 25 times higher than normal. The doctor ordered extensive genetic screening and everything short of a biopsy (we refused). During this time, his ALT reached over 1,000.

Through research and connecting with other MTM families, I learned this same crisis had happened to many children when they switched formulas. Most ended up on peptide- or amino acid–based formulas plus medication (Brenden has been on that regimen ever since). The hepatologist concluded that XLMTM boys may have a “bile transport defect.” Gallbladder sludge leads to malabsorption of vitamins A, D, E, and K. This directly affects PT-iNR and causes the bile salts to build up.

He started a regimen that required ursodiol (to clear gallbladder sludge) and colestipol (a bile salt sequestrant). Once on medication, his levels gradually improved, though it took a long time. A special liver scan showed no permanent damage, thank God. With an ALT over 1,000, the doctor was shocked that his liver wasn’t damaged!

Meanwhile, after a routine pediatrician appointment after we were getting these enzyme levels settled, the doctors thought it would be ok to do a childhood vaccination. His ALT spiked again (live vaccines can temporarily raise these numbers) and took nearly a year to normalize. Doctors and nutritionists concluded that Brenden couldn’t process Pediasure because it’s too heavy in sugar and carbs. This led to the gallbladder sludge. So ever since, he’s been on Peptamen Jr, which is amino acid–based and includes peptides and MCT oil. They’ve told me that my insistence on including Nourish likely saved him from complete disaster, since he was at least getting some plant-based proteins during that time.

Since Brenden’s crisis, I’ve been contacted by many parents (probably at least 20) who went through similar situations when their children switched formulas around age one. One boy had nearly the same experience; he now does great on Nourish and ursodiol. Clearly, the problem wasn’t Nourish. It was the Pediasure in our case, that sparked the bile transport defect.

Today, more than five years later, Brenden is incredibly healthy with perfect liver markers and no recurrence. He’s still on the same dosage of medications, even at higher body weight/height. Because suctioning and limited mobility can cause fluid loss and constipation, he needs a lot of fluids: about 1,250 mL of Peptamen Jr daily plus roughly 1,000 mL of water flushes (about four cups total). We now check his liver levels annually and do ultrasounds every two years.

Looking back, I wish I had known this from the start. That entire experience easily took 15 years off my life. However, I now try my best to be there to support other families, so they can learn from our experience.

by Jessica Gregory, mom of Brenden

You can find out more on the suggestions for liver testing here: Liver Summary – updated September 2023 (PDF)

*Glossary

What is ALT? Alanine aminotransferase (ALT) is an enzyme found inside liver cells. Liver enzymes, including ALT, help your liver break down proteins to make them easier for your body to absorb. When your liver is damaged or inflamed, it can release ALT into your bloodstream. This causes your ALT levels to rise.

What is AST? Aminotransferase (AST) is an enzyme that’s present in various tissues of your body. An enzyme is a protein that helps trigger chemical reactions that your body needs to function. AST is found in the highest concentrations in your liver, muscles, heart, kidney, brain and red blood cells. A small amount of AST is typically in your bloodstream. Higher-than-normal amounts of this enzyme in your blood may be a sign of a health problem. Abnormal levels can be associated with liver injury.

What is Bilirubin? Bilirubin is a brownish yellow substance found in bile. Bile is a fluid in your liver that helps you digest food. If your liver is healthy, it will remove most of the bilirubin from your body. But if it rises due to an underlying health problem it can cause Jaundice.

What is Jaundice? Jaundice is a condition in which the skin, whites of the eyes and mucous membranes turn yellow because of a high level of bilirubin, a yellow-orange bile pigment. Jaundice has many causes, including some medicines; a natural genetic disposition (Gilbert’s Syndrome); or more serious underlying problems like hepatitis; gallstones and tumors. In adults, jaundice usually doesn’t usually need to be treated.