Vitamin D deficiency is a major risk factor for bone loss and fracture. Although hypovitaminosis D has been detected frequently in elderly and housebound people, the prevalence of vitamin D deficiency among patients hospitalized on a general medical service is unknown.

As the risks of allogeneic blood transfusion (ABT)–transmitted viruses were reduced to exceedingly low levels in the US, transfusion-related acute lung injury (TRALI), hemolytic transfusion reactions (HTRs), and transfusion-associated sepsis (TAS) emerged as the leading causes of ABT-related deaths. Since 2004, preventive measures for TRALI and TAS have been implemented, but their implementation remains incomplete. Infectious causes of ABT-related deaths currently account for less than 15% of all transfusion-related mortality, but the possibility remains that a new transfusion-transmitted agent causing a fatal infectious disease may emerge in the future. Aside from these established complications of ABT, randomized controlled trials comparing recipients of non–white blood cell (WBC)–reduced versus WBC-reduced blood components in cardiac surgery have documented increased mortality in association with the use of non-WBC–reduced ABT. ABT-related mortality can thus be further reduced by universally applying the policies of avoiding prospective donors alloimmunized to WBC antigens from donating plasma products, adopting strategies to prevent HTRs, WBC-reducing components transfused to patients undergoing cardiac surgery, reducing exposure to allogeneic donors through conservative transfusion guidelines and avoidance of product pooling, and implementing pathogen-reduction technologies to address the residual risk of TAS as well as the potential risk of the next transfusion-transmitted agent to emerge in the foreseeable future.

In 2002, as mosquitoes carried West Nile virus across the United States, infecting 4200 people, 23 confirmed cases of transfusion-transmitted infection and 7 related deaths were reported.¹ This was a dramatic demonstration that an emerging agent can threaten the safety of the blood supply. Because the virus's incubation period is usually 3 to 15 days and transmission by transfusion stood out against the background of a mosquito-borne epidemic, these transmissions were recognized quickly, nucleic acid–amplification technology was adapted for the detection of the virus, and the Food and Drug Administration (FDA) and Health Canada mandated the screening of donated blood . . .