[Usefulness of immature platelet fraction measurement for diagnosis and monitoring of iron deficiency associated thrombocytopenia: about two cases]. / Apport de la mesure de la fraction de plaquettes immatures dans le diagnostic et le suivi des thrombopénies ferriprives : à propos de deux cas.

Iron deficiency anemia is frequently associated with thrombocytosis. However, in some rare cases of very severe iron deficiency, a thrombocytopenia may occur. This condition may lead to a misdiagnosis of immune thrombocytopenic purpura and thus to unnecessary tests in this context. Here we report two patients who presented with iron deficiency associated thrombocytopenia rapidly corrected after martial supplementation. We then discuss the value of measuring immature platelet fraction (IPF), which represents the population of newly formed platelets containing a greater amount of residual RNA. For both cases, low IPF values at admission indicated a central origin of thrombocytopenia with decreased platelet production, which is the pathophysiological mechanism of iron deficiency associated thrombocytopenia.

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. OBJECTIVES: 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. CONCLUSION: 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.