Relationship between vitamin D deficiency and bone fragility in sickle cell disease: a cohort study of 56 adults.
BACKGROUND
Recent studies suggest that patients with sickle cell disease (SCD) have profound vitamin D (VD) deficiency. Limited data exist on the effect of VD deficiency on bone fragility in these patients.


OBJECTIVE
To assess the prevalence of VD deficiency in adults with SCD and its consequences on bone metabolism and fragility.


METHODS
This prospective study included 56 SCD adult patients (mean age 29.8 ± 9.5 years), in a clinically steady state. Clinical and laboratory data were recorded. Bone mineral density (BMD) was measured using dual X-ray absorptiometry. Fracture history, BMD, avascular osteonecrosis, H-shaped vertebra and markers of mineral metabolism were compared between two groups of patients presenting very low (≤ 6 ng/mL, n=26) (group 1) and low (>6 ng/mL, n=26) (group 2) 25(OH)D concentration, respectively.


RESULTS
Median 25(OH)D concentration was 6 ng/mL. VD deficiency (25(OH)D <10 ng/mL) was found in 42 out of 56 patients (75%) and secondary hyperparathyroidism in 40 (71.4%). History of fracture was documented in 17 patients (30.3%), osteopenia and/or osteoporosis in 39.6% of patients. Overall, patients of group 1 were more likely to have sustained a fracture (42.8%) compared to patients of group 2 (17.8%) (p=0.04). These patients had also lower body mass index and significantly higher parathyroid hormone, C-terminal telopeptides of type I-collagen and bone-specific alkaline phosphatase serum levels. There was no difference between group for BMD, avascular osteonecrosis history, H-shaped vertebra, and disease severity markers.


CONCLUSIONS
This study suggests that VD deficiency is a key feature in SCD-bone disease. It is highly prevalent and associated with hyperparathyroidism, bone resorption markers, and history of fracture. The optimal supplementation regimen remains to be determined.
Service de médecine interne, Faculté de médecine Paris Descartes, Sorbonne Paris-Cité et Assistance publique - hôpitaux de Paris, hôpital européen Georges Pompidou, 75908 Paris, France. jean-benoit.arlet@egp.aphp.fr
Jean-Benoît
JB
Arlet
Marie
M
Courbebaisse
Gilles
G
Chatellier
Dominique
D
Eladari
Jean-Claude
JC
Souberbielle
Gerard
G
Friedlander
Mariane
M
de Montalembert
Dominique
D
Prié
Jacques
J
Pouchot
Jean-Antoine
JA
Ribeil
D000328:Adult; D000755:Anemia, Sickle Cell / Q000150:complications / Q000503:physiopathology*; D001842:Bone and Bones / Q000503:physiopathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications / Q000503:physiopathology*
D014807:Vitamin D; C104450:25-hydroxyvitamin D