Hypercalciuria in children with haemophilia suggests primary skeletal pathology.

Several factors can compromise optimal bone mass accrual during childhood and predispose to osteoporosis later in life. Patients with haemophilia are already at risk of low bone mass during childhood, partly due to reduced physical activity related to joint bleeds and haemarthrosis. The introduction of primary prophylaxis with regular infusions of the deficient coagulation factor has enabled reduction or prevention of haemophilic arthropathy. Finnish children with severe haemophilia start prophylaxis early and are encouraged to participate in physical activities. We hypothesized that prophylactic therapy would ensure normal childhood bone mass development and carried out a case-control study in 29 children with haemophilia (2 mild, 6 moderate, 21 severe) and 58 age-matched controls. Their bone health was determined by fracture history, blood and urine biochemistry, bone densitometry and spinal imaging. Bone mineral density was lower in children with haemophilia but there was no evidence for significantly increased fracture rate. The patients had significantly higher urinary calcium excretion and higher serum calcium concentration, and reduced bone resorption as compared with the controls. Our findings suggest primary skeletal pathology, resulting in increased urinary calcium loss and altered bone metabolism, which may over time contribute to the development of osteoporosis in patients with haemophilia.