Vitamin D deficiency is widespread

Recommended dosages of essential vitamin are insufficient for children with cystic fibrosis

By: Lindsey Hutzler

Posted: 11/13/08

Physicians at Hopkins Children's Center have been studying vitamin D deficiency in juvenile patients with cystic fibrosis, a hereditary disease that affects the exocrine or mucus glands of the intestines, pancreas, lungs and liver.

Cystic fibrosis results in frequent lung infections and decreased secretion of pancreatic enzymes, which in turn leads to difficulty in absorbing fat-soluble vitamins.

As such, children with CF are often at risk for malnutrition, as their condition makes it nearly impossible for them to absorb the necessary nutrients.

Deanna Green, a pediatric pulmonologist at Hopkins Children's Center, Peter Mogayzel, director of the Hopkins Children's Cystic Fibrosis Center and colleagues studied 262 children with cystic fibrosis.

They found current recommendations for correcting vitamin D deficiency in children with CF to be too low, leaving them at risk for bone loss and rickets.

Despite being provided with dosages of the vitamin equal to or greater than the current recommendations to treat the deficiency, approximately half of the participants in the study consistently had low bloodstream levels of vitamin D.

The researchers decided to treat adults and children with cystic fibrosis with 50,000 IU (standard unit for drug dosages) of ergocalciferol, a form of vitamin D, every day over the course of four weeks in an attempt to alleviate the deficiency. The deficiency is defined as less than 30 nanograms of vitamin D per cubic millimeter by the Cystic Fibrosis Foundation.

They found that the recommended 50,000 IU that was given weekly over the span of eight weeks to be effective in a mere 33 percent of patients and a twice-weekly dose to be effective in 26 percent of patients.

In comparison, 43 percent of children with CF who were treated three times a week with the identical dosage showed improvements.

Researchers have just completed an additional study, which found that 50,000 IU daily over the course of 28 days only worked over the short term.

"This higher dose only transiently improves vitamin D levels," Mogayzel said. "Our new approach, which we just instituted in the clinic, is to increase the routine dose of vitamin D for every patient."

"We are using cholecalciferol (vitamin D3), which some researchers feel is better absorbed than the ergocalciferol (vitamin D2) that we were using to treat vitamin D insufficiency."

An additional roadblock to patients coping with CF is that their level of vitamin D varies according to the time of year. Sunlight is necessary for vitamin D to be synthesized in the skin. When the number of daylight hours decreases and temperatures drop, the majority of the population tends to spend more time indoors.

Thus 83 percent of patients with Cystic Fibrosis had deficient levels of vitamin D during this time of the year, compared to near-optimal levels during the spring and summer months.

Although optimal levels of vitamin D to treat those with CF suffering a deficiency are yet to be found, researchers are in agreement that higher levels will allow patients to survive well into adulthood more often than ever before.

Sufficient levels of the vitamin will help prevent such issues as bone disease and osteoporosis as the population of CF patients is able to survive for longer periods of time.

Lower levels of vitamin D affect even the general population. In August, researchers at Hopkins concluded that having lower levels of the vitamin led to an increased death rate as high as 26 percent, in addition to a greater death rate from heart disease and a higher chance of developing breast cancer or facing depression.