Vitamin D may prevent osteoporosis in EPP patients, study finds
Researchers suggest supplements as part of treatment guidelines
Vitamin D plays a crucial role in maintaining and enhancing bone mineral density in people with erythropoietic protoporphyria (EPP), according to a study from the Netherlands.
EPP patients in the study had high prevalence of osteopenia, or lower-than-normal bone density, and osteoporosis, a more severe form of bone loss.
“We suggest that future guidelines on the treatment of EPP include continuous vitamin D monitoring, supplementation, and a one-time [bone density] scan for all adult EPP patients,” the researchers wrote. “Follow-up … scans can be considered to assess treatment effects or [bone density] deterioration in patients ineffectively addressing their vitamin D deficiency.”
The study, “The impact of minimal sunlight exposure on bone health: insights from a cohort study in erythropoietic protoporphyria,” was published in The Journal of Clinical and Endocrinology & Metabolism.
EPP is a type of porphyria — a group of diseases caused by disruption in the production of heme, a protein component essential for oxygen transport in the body — caused by mutations in the FECH gene, resulting in a deficiency of the terminal enzyme involved in heme production. The disease is marked by skin hypersensitivity to sunlight due to the accumulation of protoporphyrin IX, a component of heme, which can start in early childhood. This symptom may lead to severe pain, light-avoiding behavior that limits daily and social activities, and vitamin D deficiency.
Vitamin D and osteoporosis
While previous studies involving EPP patients have found they have a high prevalence of osteoporosis, a condition characterized by reduced bone mineral density and leading to fragile bones and an increased risk of fractures, none assessed the impact of available EPP treatments, such as Scenesse (afamelanotide) or cholecalciferol (vitamin D3), on bone mineral density in this population.
The researchers at Erasmus University Medical Center analyzed data from adults with EPP who underwent at least one DEXA scan, an assessment of assess bone mineral density, at their specialized center.
A total of 139 patients, with a mean age of 39.5 when the first exam to assess bone density was performed, were included in the analysis. A quarter of the patients were older than 50, and men and women were equally represented.
Low bone density classified as osteopenia affected 39.6% of the patients, while osteoporosis affected 15.1%. Those diagnosed with osteoporosis had a significantly higher average age — 51.2 — than those with normal bone mineral density, whose average age was 37.4.
At a follow-up scan, available for 89 patients at a mean of about 3.5 years after the first scan, the proportion of patients with osteopenia increased to 48.3%, while those with osteoporosis rose to 18%.
A total of 68 patients (46.6%) experienced fractures. In about a third (50 patients) the fracture was related to osteoporosis, most commonly in the wrist and caused by falling.
The risk for osteoporosis was significantly associated with age. The risk for osteopenia, although not statistically significant, was associated with persistent vitamin D deficiency and body mass index, a measure of body fat based on height and weight.
Among EPP patients receiving osteoporosis treatment, such as bisphosphonates or denosumab, all experienced improved bone mineral density.
Being a woman, having a baseline vitamin D deficiency, or not taking cholecalciferol were associated with higher odds of increasing bone mass density, while treatment with Scenesse did not improve bone density.
Both vitamin D deficiency and higher BMI were significantly associated with a decrease in bone density.
Further analysis revealed that patients with adequate vitamin D levels between baseline and follow-up evaluations were more likely to experience increases in bone density, while those with persistent vitamin D deficiency had declines in bone density.
“EPP is a natural model for lack of sunlight exposure and vitamin D deficiency, underlining the importance of lifelong adequate vitamin D status for bone health in the general population,” the researchers wrote.
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