CHAPEL HILL -- North Carolina researchers have discovered new evidence that nutritional rickets, a bone-weakening condition in infants and children caused by too little vitamin D, is making a comeback, especially among breastfed black children. Other dark-skinned children may be at risk for what appears to be a growing, potentially crippling problem, physicians say.
Surprisingly, causes may include more women breastfeeding, fewer infants receiving vitamin D supplements, and mothers and children being exposed to less sunlight than in the past. Breastfeeding still needs to be encouraged, the researchers say, but all dark-skinned, breastfed infants ought to receive vitamin D supplements.
Doctors at the University of North Carolina at Chapel Hill School of Medicine identified and treated 17 cases of nutritional rickets between 1990 and 1999, while colleagues at Wake Forest University School of Medicine found and treated another 13. More than half the cases occurred in 1998 and the first half of 1999. They also received reports of other cases across North Carolina and the nation.
Working together, the researchers described their findings in a paper appearing in the August issue of the Journal of Pediatrics.
"Nutritional rickets, once a major problem in industrialized nations, largely disappeared in this country beginning in the 1930s when it became law that vitamin D had to be added to milk," said Dr. Henry N. Kirkman Jr., Kenan professor emeritus of pediatrics at UNC-CH and an expert on the illness. "The only cases of rickets I treated between 1965 and about 1990 were inherited ones. Then, to my surprise, nutritional rickets began showing up in our clinic in the early 1990s."
Kirkman checked with his counterpart at Wake Forest University, Dr. Robert P. Schwartz, a pediatrics professor who said he also was beginning to see cases of nutritional rickets. All occurred in black children whose mothers had breastfed them.
Besides Schwartz and Kirkman, authors of the paper are Drs. Shelley R. Kreiter, a WFU pediatrician, and Ali S. Calikoglu, Marsha L. Davenport and Philippa A. Charlton, assistant professor, associate professor and former fellow, respectively, of pediatrics at UNC-CH.
Their study involved analyzing all physical and X-ray findings on diagnosed children, along with chemical tests revealing vitamin D levels and certain minerals. They also determined that breastfeeding increased more than four-fold among black women and almost two-fold among white women enrolled in the N.C. Women, Infants and Children (WIC) program between 1988 and 1998.
The average length of breastfeeding among affected children was 12.5 months, and the average age at diagnosis was about 15 months, the team found. In two-thirds of cases, patients were shorter in length than more than 95 percent of all other children.
"We are all strong proponents of breastfeeding, and we're pleased that it's been increasing, but we think this may partially explain why we're now seeing nutritional rickets," Kirkman said. "Rickets is a very cruel disease that causes bowed legs, shorter stature and can even be life-threatening. If treatment isn't started early enough, it becomes irreversible. Surgery helps in some cases but not all."
Vitamin D can either be taken in through diet or produced naturally by the skin in response to sunlight, he said. But just as darker skin protects people from excessive sunlight, it also decreases natural production of vitamin D. Although almost perfect otherwise, breast milk is not a good source of vitamin D. Also, on average, people of all races in the United States are outdoors far less than their ancestors.
"For the past million years, people didn't spend a lot of time watching television in homes with central heating and air conditioning," Kirkman said.
"This is a significant problem, and it's time for a change in physician practice," Davenport said. "We believe that all dark-skinned breastfed infants should receive vitamin D supplements beginning in early infancy.
Calikoglu grew up and trained in Turkey, where he saw and treated many nutritional rickets cases. Schwartz has been instrumental in persuading the state's WIC program to pay for free vitamins for all breastfed infants.
Note: Davenport and Calikoglu can be reached at 919-966-4435, extensions 232 and 241, respectively. Davenport also can be paged at 800-216-1392. Kirkman's number is 919-942-5651. Kreiter's number is 336-716-1292, and Schwartz can be reached at 336-716-3199 or paged at 800-277-7654.
By DAVID WILLIAMSON UNC-CH News Services
Journal
The Journal of Pediatrics