The couple sat in silence as they drove home from Blank Children’s Hospital in Des Moines. Their 5-month-old baby appeared to be dwarfed by the pram tied to the back seat. He’s tiny. It hasn’t grown since it was 2 months old. He weighs only 10 pounds – only 3 pounds heavier than when he was born.
The baby had been breastfed since birth, but his mother realized right away that he had more difficulty doing so than his three older brothers. Try putting breast milk in a bottle to see if it makes breastfeeding easier. When that didn’t work, she tried adding infant formula. He spits often; sometimes it looks as if more is coming out than coming in. His pediatrician started him on an acid-reducing medication. It doesn’t seem to do much either.
Other than his size, he looks healthy. He was active. He was able to meet all of his milestones. He can hold his head high. He can roll. His fontanelle, the soft spot on the top of his head, is flat – as it should. The pediatrician advised him to be patient, but when the boy still hadn’t gained weight at his 4-month visit, she sent a blood sample to the lab.
In the afternoon of the same day, parents received a call announcing the results. The baby had worrisome blood chemistry abnormalities. His blood salt levels were so high that it could cause a seizure. In fact, it was so high that if left unresolved, he could die. The parents rushed the boy to Blank Children’s Hospital.
Problems in the brain? Or kidney?
Samples taken at the hospital emergency room quickly confirmed the abnormality. The child’s sodium level was 159, 10 points above normal. The high number told his doctors not only that he had too much sodium but that he did not have enough water in his body, that he was very dehydrated.
Normally, when there is too much sodium in the body, the brain activates the urge to drink to provide more water. The brain also asks the kidneys to keep as much water as possible.
The brain communicates all of this with a hormone called vasopressin. Problems with vasopressin can cause a disorder first described in the 18th century as diabetes insipidus (DI) – a disease that produces profuse and watery (tasteless) urine.
The combination of high sodium and watery, dilute urine in the child immediately led doctors to suspect DI. Yet his urine is almost all water. Why? Is the pituitary gland in his brain unable to make hormones? Or is there a problem at the receiving end of the message in his kidneys?
No matter where the problem begins, there are medications that can help. Doctors gave the baby two medications commonly used to control high blood pressure, which trigger the kidneys to excrete sodium. Almost immediately, your baby’s sodium begins to drop. That shows that the baby has had DI If so, is the problem with the brain, which produces hormones, or the kidneys? How the problem is handled depends on its origin.
An MRI scan was done to look for signs of a problem in the pituitary gland. It looks normal. Doctors determined the problem was probably in his kidneys. They sent out samples to look for the genetic reason for his abnormality, but those results wouldn’t come back for weeks.
In the meantime, they continued to give him medicines to help him run out of salt. And slowly the levels drop. After a few days of taking these medicines, the baby’s chemicals were completely normal. The parents told them he should start gaining weight now. But he didn’t. On the day the doctors decided the baby was well enough to go home, he still hadn’t grown a bit.
Still not growing
Parents were instructed to feed their children every three hours to help them get the maximum amount of calories. They should see their pediatrician again and see a geneticist. Then they were sent home. They feel strongly that their child is not ready to leave the hospital. He was admitted to the hospital with a diagnosis of “failure to grow,” and he is still failing to thrive. On the growth chart, he’s at zero percent. Zero. They made this argument with the boy’s doctors. He will gain weight now because his chemicals are normal, they have been told. Just give him time.
The child’s parents felt that he did not have the time, that his life was still in danger. So early the next morning, the parents and the baby got in the car to return. They talked about an appointment with genetics specialists at the University of Iowa’s Stead Children’s Hospital in Iowa City, two hours away. When they got there, the parents shared their concerns. Is the baby not gaining weight due to DI? Or is there something else going on?
At Blank Hospital, the child was tested for cystic fibrosis. The test yielded no results. Dozens of other disorders can interfere with a baby’s development. The parents and baby were sent to the lab to have blood drawn to look for other genetic abnormalities and to the cardiology department to make sure the baby’s heart was normal.
The geneticist also wants the baby to be examined by a pediatric gastroenterologist. He was clearly having trouble feeding and seemed to have spat out much of what he was able to absorb. The geneticist contacted Dr Eyad Hanna, who saw the child later that day. In just a few minutes, the gastroenterologist decided that the baby was too small to send home. Like the child’s parents, he worries that if the baby can’t gain weight in the hospital, he can’t do it at home either. The baby was placed in Hanna’s care and was started on round-the-clock feeding to try to get her back on the growth curve. Hanna also contacted a pediatric nephrologist, Dr Pat Brophy, who recommended extra water to replace the amount of water the boy had lost in his urine. Usually doctors advise mothers not to give water to their babies because breast milk already has enough water in it. But clearly this is no ordinary child. And because of reflux and difficulty feeding, Brophy also recommends putting a tube in your baby’s stomach – a nasogastric tube or a G-tube – to make sure he’s getting enough calories, medication, and fluids. necessary supplement.
The baby continued to spit out the large amount of milk and water it received. Usually, this type of saliva disappears as the baby’s esophagus lengthens and the stomach gets larger. But this baby won’t grow at all without extra nutrition. Hanna recommends adding infant formula as well as dry baby food to the milk. He had them widen the hole in the nipple of the bottle so that the thick liquid could pass through easily.
Back to the growth curve
And then they wait. Test results are not clear. He does not have cystic fibrosis. His heart is completely normal. But even if the negative results slowly come in, the baby’s parents can see that the baby is making progress just by getting enough calories and especially the necessary amount of water. Each night, he would take an 8-ounce glass of water through his G-tube. Every day he was fed every three hours for a total of 1,300 calories. And gradually he began to gain weight – 30-40 grams a day. He was hospitalized for nearly two weeks, by the time his parents got home, he had gained more than a pound. It took him a few more months to get back on the growth curve. Only then did they receive the results of a genetic test, confirming what they already knew: The baby had DI
That baby is now 7 years old. He is learning to live with DI. He continues to take medicines that help me get rid of sodium in my body. He has to go to the toilet often. And he must drink a lot of water to replace all that he lost in the urine. He’s not as big as his brothers – not yet, and possibly never. But he was still growing and developing, and as far as his parents were concerned, that was more than enough.
Lisa Sanders, MD, is a contributing writer for the magazine. Her latest book is “Diagnosis: Solving Medical Mysteries.” If you have a resolved case to share, write to her at Lisa.Sandersmdnyt@gmail.com.