Osteoporosis affects approximately 25% of individuals with hereditary hemochromatosis, report researchers who also identified the factors influencing this relationship.
"Hereditary hemochromatosis is a common inherited disorder with a prevalence of about 1 in 300 in Caucasians, characterized by increased intestinal iron absorption and progressive accumulation in parenchymal tissues, leading to organ damage during the forth/fifth decade of life," explain Silvia Fargion (Universita degli Studi di Milano, Italy) and associates.
Hereditary hemochromatosis and osteoporosis have previously been linked in small studies. It is thought that the excess iron concentrations associated with the disorder reduce BMD by inhibiting osteoblast activity and bone apposition.
However the researchers note, in the journal Osteoporosis International, that "few observations are available on the role of acquired factors influencing iron absorption."
Fargion and colleagues used dual energy X-ray absorptiometry to measure BMD at the lumbar spine in 87 consecutive patients with hereditary hemochromatosis and to at the femoral neck in 66 of them.
The analysis showed that 25.3% of the patients had osteoporosis and 41.4% had osteopenia, with typical Z-scores of -0.92 and -0.35 at the lumbar spine and femoral neck, respectively.
Furthermore, T-score at the lumbar spine was significantly and independently correlated with bone turnover, as shown by measuring levels of bone-specific alkaline phosphatase, as well as the presence or absence of hypogonadism or menopause, and iron overload.
In addition, the researchers showed that the presence of osteoporosis in the lumbar spine among 81 of the patients was significantly more likely as body mass index decreased, total levels of bone-specific alkaline phosphatase increased, and the amount of iron removed from a patient during phlebotomy increased, at odds ratios of 0.73, 1.17, and 1.53.
The relationship between osteoporosis and hereditary hemochromatosis was independent of genetic background.
Concluding, the authors suggest that their study could have been strengthened by measuring femoral neck BMD in all patients as well as more thoroughly analyzing levels of bone turnover markers and concentrations of 25-hydroxy vitamin D.