NEW YORK (Reuters Health) - In an unselected group of cystic fibrosis (CF) patients, 70% were found to have suboptimal levels of vitamin K, British researchers report. The say the findings suggest routine vitamin K supplementation for CF should be considered.
Currently, the team notes in their report in the May issue of Pediatrics, vitamin K supplementation is not routine in UK clinics, although patients do routinely receive vitamin A, D and E.
While studies have not established the ideal dose of vitamin K for these patients, Dr. Steven P. Conway told Reuters Health, he and his colleagues at St. James’ University Hospital in Leeds recommend 5 to 10 mg of phytomenadione preparation, with 10 mg for children over age 5.
Their current findings also suggest a relationship between vitamin K deficiency and low bone mass in patients with CF, although they do not prove it, the investigators say. Dr. Conway noted that both osteopenia and osteoporosis are common among CF patients, particularly after adolescence.
Osteocalcin plays a key role in bone formation, while vitamin K deficiency leads to a rise in levels of undercarboxylated, and thus dysfunctional, osteocalcin, the researchers note. A high ratio of undercarboxylated to total osteocalcin “is the first functional marker to respond to vitamin K depletion and the last to respond to repletion,” they explain.
For their study, Dr. Conway and colleagues recruited 106 children with CF. Of 93 children who provided blood samples, 70% has suboptimal levels of vitamin K, meaning they had low serum levels of the vitamin, increased prothrombin levels, or both.
While the researchers found no correlation between vitamin K status and several markers of bone turnover or bone mineral content and bone density, vitamin K deficiency was significantly related to levels of undercarboxylated osteocalcin C. And the researchers found that undercarboxylated osteocalcin levels were negatively related to bone mineral density and content.
The researchers conclude: “The supplemental dose of vitamin K necessary to achieve maximal gamma-carboxylation of osteocalcin among patients with CF and the effects of these supplements on bone mineral turnover, bone mineral density and bone mineral content remain to be determined in longitudinal and controlled studies.”
Source: Pediatrics 2005;115:1325-1331. [ Google search on this article ]
MeSH Headings:Musculoskeletal Physiology: Musculoskeletal, Neural, and Ocular Physiology: Bone Density: Biological SciencesCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
