The role of sclerostin/dickkopf-1 and receptor activator of nuclear factor kB ligand/osteoprotegerin signalling pathways in the development of osteoporosis in patients with haemophilia A and B: A cross-sectional study.

AIM: Haemophilia A and B are associated with reduced bone mineral density (BMD). The aim of this study was to assess circulating sclerostin and dickkopf-1 (Dkk-1), (inhibitors of osteoblastic differentiation), as well as the receptor activator of nuclear factor kB ligand (RANKL)/osteoprotegerin (OPG) system (the major regulator of osteoclastogenesis), in patients with haemophilia (PWH), their possible correlations with clinical risk factors and the effect of ibandronate on these markers. METHODS: Eighty-nine male PWH (mean age 45.9 ± 15.3 years) and 30 age-matched healthy male controls participated. BMD was assessed by DXA. Sclerostin, Dkk-1, RANKL and OPG were measured in serum of patients, controls, as well as in ten patients receiving oral ibandronate (150 mg/mo), at baseline and after 12 months. RESULTS: Patients with haemophilia had lower circulating sclerostin (median ± IQR: 47.4 ± 26.93 vs 250 ± 250 pmol/L, P < .001), Dkk-1 (21.24 ± 17.18 vs 26.16 ± 15.32pg/mL, P = .04) and higher levels of RANKL (0.23 ± 0.03 vs 0.04 ± 0.03 pmol/L, P = .001), RANKL/OPG ratio (0.063 ± 0.25 vs 0.005 ± 0.11, P = .001) compared with controls. Patients with low BMD had higher OPG concentrations compared to those with normal BMD. Sclerostin and RANKL/OPG correlated positively with BMD. Patients with severe haemophilia had lower sclerostin concentrations compared with those with mild or moderate disease. The degree of arthropathy negatively correlated with sclerostin and Dkk-1 levels. PWH who received ibandronate showed a decrease in serum Dkk-1 without any significant effect on sclerostin and RANKL/OPG. CONCLUSIONS: Patients with haemophilia present increased osteoclastic activity coupled with compensatory increased osteoblastic activity. Ibandronate did not affect RANKL/OPG ratio, but it decreased Dkk-1.

Bone mineral density in men and children with haemophilia A and B: a systematic review and meta-analysis.

SUMMARY: Although haemophilia is not considered among the classic causes of secondary osteoporosis, the present meta-analysis provides strong evidence that men with haemophilia have a significant reduction in both lumbar spine and femoral bone mineral density, which appears to begin in childhood. INTRODUCTION: Haemophilia is not considered among the classic causes of secondary osteoporosis. The aim of this study was to systematically review the literature for case-control trials that have studied bone mass in males with haemophilia and to meta-analyze the best evidence available. METHODS: Electronic databases MEDLINE, EMBASE and CENTRAL were systematically searched for case-control trials that have studied bone mass in men or boys with haemophilia. Standardized mean difference (SMD) for bone mineral density (BMD) in the lumbar spine was the main study outcome and SMD in femoral neck and total hip BMD the secondary ones. Patient and control characteristics, such as age, body mass index (BMI), level of physical activity and blood-borne infections were recorded as possible predictors of the main outcome. RESULTS: Thirteen studies were included in the systematic review and ten in the main outcome meta-analysis. Men with haemophilia demonstrated reduced lumbar spine [random effects SMD [95 % confidence interval (CI)] = -0.56 (-0.84, -0.28), between-study heterogeneity (I (2)) = 51 %] and femoral neck BMD [random effects SMD (95 % CI) = -0.82 (-1.21, -0.44), I (2) = 63 %] compared with controls, which indicated a large and clinically significant association. Similar results were obtained for children [random effects SMD (95 % CI) = -0.92 (-1.77, -0.07), I (2) = 92 %]. No evidence of publication bias was detected. There was no evidence that age, BMI, level of physical activity or presence of blood-borne infections predicted lumbar spine BMD. CONCLUSIONS: This meta-analysis shows that men with haemophilia present a significant reduction in both lumbar spine and hip BMD, which appears to begin in childhood.

Laboratory investigation of platelet function in patients with thalassaemia.

The aim of this study was to investigate platelet function in patients with thalassaemia and to detect any relation to chelation treatment (deferasirox or deferiprone/deferiprone plus desferioxamine). Thirty-three transfusion-dependent patients with thalassaemia were included. The investigation consisted of aggregation testing of platelet-rich plasma by light transmission aggregometry (LTA) with the use of 5 agonists as well as the global test of haemostasis by means of the PFA-100 platelet function analyser. In 66.67% of the patients, there was reduced LTA to at least one agonist and in 18.18% there was reduced LTA to two or more agonists. The PFA-100 test was prolonged in 60.6% of the cases. An abnormal LTA and a prolonged PFA-100 time were recorded in 33.3% of the patients and 27.4% had a normal aggregation and PFA-100 test. No correlation between chelation regimen and either LTA or PFA-100 test was found. The abnormal LTA can be explained either by the release of ADP from the haemolysed red blood cells, which leads to defective platelet aggregation, or by the presence of two platelet populations. An in vitro effect without an in vivo impact could be an alternative explanation. In patients with thalassaemia, the reduced LTA and the prolonged PFA-100 closure time could be an in vitro effect and has a close correlation to the bleeding phenotype of each patient.

The clinical utility of bone turnover markers in the evaluation of bone disease in patients with haemophilia A and B.

Haemophilia A and B have been associated with increased prevalence of low bone mineral density (BMD). However, the utility of bone turnover markers (BTM) remains unknown. The aim of this study was to evaluate bone metabolism in men with haemophilia and to investigate associations between BTM and bone disease. Serum N- (NTX-I), C-terminal telopeptide of type I collagen (CTX-I) and tartrate-resistant acid phosphatase band-5b (TRAP-5b), as bone resorption markers, and osteocalcin (OC) and bone-specific alkaline phosphatase (b-ALP), as bone formation markers, were assessed. Seventy men with haemophilia A (n = 59) or B (n = 11) were studied. Patients with low BMD had significantly higher b-ALP concentrations compared with those with normal BMD (12.8 ± 1.60 vs. 9.72 ± 0.58 µg/L, P = 0.009), without any differences in the other BTM. NTX-I and CTX-I concentrations were negatively associated with oestradiol levels and hip BMD and positively with human immunodeficiency virus infection, number of affected joints and arthropathy scores. B-ALP and OC concentrations were negatively associated with hip BMD, severity of haemophilia and fracture history, and positively with the number of affected joints and testosterone concentrations. After multivariate analysis, NTX-I levels remained negatively associated with oestradiol levels, whereas b-ALP concentrations negatively correlated with the level of physical activity and positively with the number of affected joints. Increased bone metabolism exists in men with haemophilia and low BMD. Increased b-ALP levels may identify patients at high risk for fracture. Increased number of target joints, low physical activity and low oestradiol concentrations are independently associated with increased bone metabolism.

Management of acute bleeding in a patient with congenital afibrinogenaemia.

Congenital afibrinogenaemia is a rare bleeding disorder characterized by absence of fibrinogen and varying bleeding tendency. Treatment with fibrinogen concentrates is considered to be the best choice for afibrinogenaemic patients who experience bleeding. We report the case of a 22-year-old Greek patient who presented with large muscular haematomas and was treated with fibrinogen concentrates. The efficacy of this treatment and the problems that arose during his hospitalization are being discussed.

Fibrinogen Bbeta14 Arg-->Cys: further evidence for a role in thrombosis.

A single base substitution (C-->T) in exon II of the Bbeta fibrinogen gene resulting in an Arg14-->Cys replacement was identified in a young woman with a history of recurrent thrombotic stroke. The patient's plasma showed prolongation of the thrombin and Reptilase times, and plasma fibrinogen, which was low when determined by chronometric assay (Clauss technique) was normal by clot weight. Dysfibrinogenaemia associated with the same mutation was identified in eight family members including two siblings with a history of venous and arterial thrombosis. Fibrin monomer polymerization with thrombin, Reptilase and Agkistrodon contortrix contortrix venom was defective. Polymerization studies revealed a reduced rate of polymerization compared with normal plasma, which improved on cooling from 37 degrees C to 20 degrees C. Plasma viscosity in the affected individuals was normal. Flow cytometric analysis of platelets from the proband and another affected member showed no increase in surface bound fibrinogen. Euglobulin clot lysis time was normal. The same point mutation has been described previously in individuals with thrombosis. This family adds further to the genotype-phenotype correlation of the dysfibrinogenaemias and provides strong evidence for a genuine association of fibrinogen BbetaArg14Cys with thrombosis. The mechanism underlying a causal relationship with the increased incidence of thrombosis remains obscure but a review of related dysfibrinogens suggests that the addition of a free thiol group rather than the loss of the thrombin cleavage site may be important.