Transient mixed hematopoietic chimerism in dogs given thymic irradiation before and pharmacologic immunosuppression after marrow transplantation.

pathologic hair loss or even alopecia, was noticed. In the other 4 patients, hair was coming out in handfuls, leaving large areas of mutilating patchy alopecia. Those 4 patients reported that hair loss had begun approximately 6 weeks to 3 months after initiation of hemodialysis. We suspected that repeated anticoagulation with dalteparin, which shares many side effects with heparin,4 was responsible for the unexplained hair loss in our patients. To test this hypothesis, regional citrate anticoagulation2,3 was initiated, thus avoiding further exposure to dalteparin. Six weeks to 3 months after the anticoagulation regimen had been changed, all 5 patients reported cessation of the excessive hair loss. In patients 2 to 5, normal hair growth allowing fashionable hairstyling was observed. Citrate anticoagulation was stopped in patient 2, and excessive effluvium reoccurred some weeks after readministration of dalteparin. In patient 1, objective changes in hair growth were not observed. In summary, in 4 of 5 chronic hemodialysis patients, a clear temporal association of excessive hair loss with the start of dalteparin anticoagulation was observed. The resolution of the excessive effluvium in these 4 patients and the restoration of normal hair growth after the anticoagulation had been switched to citrate suggest that dalteparin was responsible for the mutilating alopecia. The recurrence of the hair loss in patient 2 soon after reexposure to dalteparin is a further hint in favor of this hypothesis. Our case series supports the observation of Barnes et al, who reported a potential association of alopecia with the administration of dalteparin in a child treated for sinus venous thrombosis.5 We conclude that long-term anticoagulation with dalteparin causes alopecia in some chronic hemodialysis patients. Regular hair growth can be restored by replacing low-molecular-weight heparin by regional citrate anticoagulation.