Unraveling the Mystery of CSID

Unraveling the Mystery of CSID

All too frequently, those individuals who have rare diseases spend years trying to find out what’s wrong with them, going from doctor to doctor, medication to medication, trying anything to find some relief for the pain and discomfort they are suffering.


This story chronicles the tale of a family which, after four years, was finally unable to unravel the mystery of Sucrose Intolerance caused by Congenital Sucrase-Isomaltase Deficiency (CSID) and find their youngest daughter, Emma, a path for as normal a life as possible when living with a rare disease.

Something’s Wrong

Emma was only 2 weeks old when I had to stop breast-feeding and begin giving her a highly recommended baby formula. Within a week, we realized that something was terribly wrong. She would shriek with pain unrelentingly for hours at a time. Nothing I could do, not walking her, holding her, nor rocking her could relieve her discomfort. She vomited often and had constant gas and diarrhea. She couldn’t get comfortable in any position and her body would stiffen and arch. Her older sister, Jenny, and her two half-brothers tried to help, as did my husband; but nothing any of us did could ease her pain. We tried other formulas with the same lack of success. We had never dealt anything quite like this with our other children, except a bout with reflux and silent reflux that Jenny experienced when she was a baby. A friend suggested colic, so I checked on the internet and found that much of the Emma’s behavior was similar. I read the suggestions for helping to alleviate the pain; and we put them into practice, but they didn’t work.

Seeking Emergency Medical Help

One night, after two more long weeks of Emma’s unending screaming, vomiting, and diarrhea, my husband walked in from work. Unable to deal with her pain, we took her to the emergency room (ER) at the local hospital. When we mentioned Jenny’s experience with reflux when she was a baby, the ER doctor thought maybe Emma was experiencing the same problem and treated her for reflux and silent reflux. We were given a pretty strong prescription and told to visit our pediatrician as soon as possible. Unfortunately, the medication prescribed seemed to make things worse, so we immediately we made an appointment with Emma’s pediatrician.

Visiting Emma’s Pediatrician

When we saw Emma’s pediatrician, she felt that Emma had cow’s milk protein allergy (CMPA), one of the most common childhood food allergies. It is similar to lactose intolerance, except the immune system is involved in CMPA, but not in lactose intolerance. The pediatrician suggested that I remove all dairy from her diet and try a non-dairy formula. We tried several formulas, but she vomited everything and still suffered from diarrhea, gas, and bloating. By this time, her pediatrician was at a loss and referred her to the pediatric specialty unit at the university teaching hospital close by.

Working with the Pediatric Unit

Now that we had a whole team of doctors looking at Emma’s issues, we thought that maybe we would now be able to find an answer, but things progressed from bad to worse. Emma was initially diagnosed with food protein-induced enterocolitis syndrome (FPIES), a severe condition characterized by vomiting and diarrhea caused by a rare food allergy; but that diagnosis didn’t quite fit with the symptoms Emma exhibited. Emma’s symptoms appeared immediately after eating, while the symptoms of FPIES don’t occur until hours later. Then a doctor on the unit suggested gut motility issues; we treated for that and she didn’t get any better. When another suggested small intestine bacterial overgrowth (SIBO), we began treatments for SIBO. No change in her condition. Then irritable bowel syndrome was dropped into the mix. Nothing. We tried all the treatments associated with these conditions and nothing worked. By now, Emma was 2 years old and we were no further along that we had been when she was 2 weeks old.

It was during this period that we had one of our worst experiences during this whole ordeal. One of the pediatric specialists on the unit was disdainful of my constant questioning about Emma’s diagnoses and treatment, seeming to think that my constant stress and worry were transferring to my daughter and causing her illness. She had run blood tests to determine enzyme levels in Emma’s blood. As she talked with us about Emma’s test results, she noted that all of her test had come back normal. When I asked why more than half of the tests had been highlighted, she said they were at the very low end of the normal scales. After we researched gastrointestinal enzymes, we specifically asked her to rule out CSID. She refused, saying to do that we would have to put Emma on a milk diet for at least 8 weeks for the tests to show anything. When we persisted, she said that she thought that we should wait for a year until Emma could talk and tell us how she felt. Wait a year? Not likely. Not when I had a child who could eat only five foods and was always uncomfortable, often gassy and vomiting. Instead, we were assigned to a new physician on the unit. A pediatric allergist.

Being Tested for Allergies

The pediatric allergist conducted blood tests for Immunoglobulin E (IgE) allergies, in which the body produces antibodies called IgE, causing an allergic reaction, but nothing conclusive was discovered. Because she continued to maintain a healthy weight, primarily from drinking large amounts of soy-based formula, the allergist thought perhaps Emma wasn’t really that sick. But he quickly became a believer when we tried to wean Emma onto food and the problem became worse, making her vomit and giving her constant diarrhea. She stopped gaining weight and grew more and more passive, eating little. By now, she was almost 3 years old and she began exhibiting “failure to thrive.”

Discovering Emma’s Intolerance to Sucrose

By this time, we were so frustrated and desperate that we sought the assistance of a noted homeopath living in our area. For Emma’s treatment, we were given the homeopathic treatment encased in a small sugar-coated pill. She took this pill for a couple of days and seemed calmer and more relaxed, then she started vomiting violently every time we gave her the pill. This was how we discovered that she couldn’t tolerate sucrose. While the homeopathic treatment didn’t help, it did confirm what we had expected for some time. Our daughter was sucrose-intolerant. We immediately made an appointment with a pediatric gastroenterologist at the university.

Getting the Run-Around

Because of the research we had done and because of our experience with the homeopathic treatment, we had finally figured out that Emma could not tolerate any form of sugar. When we met with the pediatric gastroenterologist, we told him about our experiences and asked him to check for celiac disease and CSID. But after he met with several other members of the pediatric unit, he said the doctors felt it was not possible for Emma to have CSID because it was so rare. He also admitted that the members of the unit were not familiar with the condition. Essentially, they were giving up on her. We went home and searched on the internet for physicians with expertise in CSID. Luckily, we were able to find a pediatric gastroenterologist with experience in CSID in private practice.

The Worst 48 Hours of Our Daughter’s Journey

We were excited to meet the new pediatric gastroenterologist until he explained what he wanted to do. Even though we went over all Emma had gone through in the past 3 and ½ years, he wanted Emma admitted to the hospital for two days so he could observe her symptoms and conduct tests first-hand. Those two days we spent with her in the hospital were probably the worst 48 hours of our journey with Emma.

The pediatric gastroenterologist activated all her symptoms by giving her foods that she couldn’t tolerate so that he could observe her and carry out some tests. After a day, she became progressively lethargic and pale and refused to eat anything at all. Her stomach was very badly bloated, she had terrible diarrhea and burns on her bottom. They were unable to carry out the tests they needed because she refused to swallow the barium liquid and screamed. She became so sick so rapidly that we were sent home early.

Finally Diagnosing CSID

While those 48 hours were the worst in our experience, her hospital stay gave the green light for Emma to have the gastrointestinal endoscopy and biopsies that we really wanted. We had researched enough by now to know that a disaccharidase assay test using a small bowel biopsy could measure for the enzymes lactase, sucrase, isomaltase, and maltase. This biopsy is the gold standard used for diagnosing CSID. After the doctor saw Emma’s reaction in the hospital, he scheduled the procedure immediately.

Analyzing the Results

The results of the assay were very surprising. When we were told Emma’s results were normal and that she didn’t have CSID, we were shocked. We had been so sure that Emma had CSID. That’s when I asked to see the results myself. As I reviewed the data with the pediatric gastroenterologist, I realized that although the numbers were within the normal range, they were right at the lowest end of normal. They had also tested for only two of the disaccharidase enzymes, when they should have tested for all four. How could this happen? How could they not have completed the assay we had expected? As we walked out of the doctor’s office, we decided to seek a second opinion, this time from a noted professor in pediatric gastroenterology who was a CSID specialist located at a large university about 100 miles from our home.

Meeting with the Professor

Meeting with the professor was like a breath of fresh air. We were immediately comfortable with him. He thoroughly examined Emma, asked questions about our family’s history since CSID is a genetic disease, and reviewed her gastrointestinal endoscopy results. In all our other interviews and meeting, no one had asked us about family history. I related that I had never been able to tolerate sugar very well and avoided eating sugary foods. It was so much my way of life, I hadn’t even connected my avoidance of sugar with Emma’s CSID. With my history and Emma’s CSID symptoms and test results, the professor suggested that we try a potential treatment to see if that treatment would help Emma. He also conducted a second gastrointestinal endoscopy and tested for all four disaccharidase enzymes and found Emma was at the low end of normal for all four.

Treating Emma’s Disease

Nothing could have prepared us for the change we saw in our little girl with proper treatment. Immediately, she had much more energy, and became the precocious 3-year-old she was meant to be. No more debilitating pain and fatigue. Normal bowel movements. Less fear in trying new food. No more vomiting. Joy instead of tears. It was amazing and rewarding to see that she began acting like a normal kid, eager to play with the other children in the neighborhood.

Getting a Final Diagnosis

We were so lucky to find our professor. Based on Emma’s test results, even though they were just barely within the normal range, her symptoms, a positive response to treatment, and some diet modification, the professor definitively diagnosed her with CSID. His ability to view the totality of Emma’s tests and range of experiences instead of so rigidly adhering to low-normal test numbers, as other pediatricians and pediatric gastroenterologists had done, gave us the finality we so desperately needed to begin to help Emma learn to live with CSID. We know that she will never be cured, that she won’t grow out of CSID; but we also know what we need to do to help her.

Catching up with Emma

Emma has now been treated for CSID for 5 months, and she is just like a normal 4-year-old girl, exploring everything, making new friends at the playground, full of life and energy, going to birthday parties, and friend’s houses. She’s still on a limited diet, but there are so many good, healthy recipes for those with CSID that the whole family has begun eating healthier foods. We know how many grams of starch and sugar she can tolerate each day, so we can adjust her diet accordingly.

Finding Help in Diagnosing Rare Diseases

After all that Emma and our family have been through, I’d like to suggest a few ways that doctors who are unfamiliar with a given rare disease can learn to make better diagnoses. First, they need to really listen to parents and ask as many probing questions as possible. Next, they should admit when they don’t have the answer and try to find someone who can actually help you out. Just those two items could have actually saved us years in trying to unravel the mystery of CSID and more quickly get Emma on the right path. Besides strictly relying on a doctor, search the internet. More and more information is available about rare diseases, and you can find the facts you need to justify your suspicions, as well as locate the right provider and ask the right questions once the provider is found. On more than one occasion in our search, we actually knew more than the physician we were consulting. So, use a variety of resources to find out as much as you can and be prepared to stand up for yourself and your ideas.

Never Giving Up

There is nothing more distressing than a chronically ill child who is in immense pain and who doesn’t have the words to tell you what’s wrong. But you can’t give up. Your path may be long and winding, but if you persevere, you will find out what’s happening with your child and what you can do to make life better, like we did for Emma.

Remember it took us four – four! – years to finally get a definitive diagnosis for Emma. Many times, we were so frustrated, we just wanted to give up, but we couldn’t bear to see her suffer and were determined we would find a way to make things right. You can do this! It may be hard, but you can help solve the mystery of CSID and other rare diseases.

This story includes the insight of one patient. Individual experiences can and do vary.

Sucrose Intolerance may be more common than you think.