Blood and Bone - Epidemiological studies on the association between blood and bone

Abstract: Introduction: Preclinical and clinical studies have suggested that blood- and bone cells are interconnected. Aims: To study the association between hematological variables, specifically serotonin, erythropoietin (EPO), hemoglobin (Hb), neutrophil-, lymphocyte-, and platelet count, and bone mineral density (BMD), and/or risk for fractures (paper I-III). To study the risk for hip fractures in patients with lymphoma (paper IV). Methods: In paper I-III data from MrOS (The Osteoporotic Fractures in Men Study), a prospective, population-based study, was used. Men in the ages 69-81 years were randomly selected from Gothenburg (n=1010), 2002-2004. In the second part of paper I, additional cohorts from Uppsala and Malmö were used. Baseline data included blood tests (serotonin, EPO, Hb, neutrophil-, lymphocyte-, and platelet count) and dual x-ray absorptiometry (DXA). Subjects were followed until the end of 2013. In paper IV adults ≥18 years diagnosed with lymphoma between 1995 and 2015 were identified in the Swedish Cancer Register. Data on the Swedish population and lymphoma patients was retrieved from Statistiska Centralbyrån, and hip fractures were identified via the Inpatient Register. The risk for hip fractures in patients with lymphoma was compared with that of the Swedish population. Results: Serotonin was negatively associated with total hip BMD. Men with serotonin in quintile 5 had an increased risk for all fractures, nonvertebral osteoporotic fractures and hip fractures. In men with normal renal function EPO was positively associated with total hip BMD, inflammation, and comorbidities, as well as increased risk for all fractures and major osteoporotic fractures. Platelet- and neutrophil count, and not Hb and lymphocyte count, were negatively associated with total hip BMD. Women with lymphoma had increased risk for hip fracture compared with the Swedish population. Conclusions: The results support the hypothesis that blood and bone are interconnected. Serotonin and EPO both predict for fractures in elderly men. Platelet- and neutrophil count are associated with BMD. Physicians treating lymphoma patients should be aware of the increased risk for hip fractures in women.