Effect of different healing stages on stable isotope ratios in skeletal lesion

Abstract

Introduction:Physiological stress is one of the various factors that can have animpact on stable isotope ratios. However, its effect on bone collagen stable isotoperatios is still not fully understood. This study aims to build on previous research onhow different disease stages may affect bone collagen stable isotope ratios.Materials and Methods:Carbon (δ13C) and nitrogen (δ15N) isotope ratios wereassessed in 33 skeletons that retained evidence of infectious disease and healed frac-tures. Samples were taken from active lesions (long bonesn= 14; ribsn= 4), healedlesions (long bonesn= 10; ribsn= 9), or a fracture callus (long bonesn= 9; ribsn= 3). Results were compared to stable isotope ratios calculated for regions on thesebones that did not retain evidence of disease or fracture.Results:Long bones with active lesions had a significantly higher averageδ15N(δ15N = 11.1 ± 0.9‰) compared to those without lesions (δ15N = 10.7 ± 0.7‰;p= .02), while fracture calluses showed the largest range for bothδ15N andδ13C. There were no significant differences in stable isotope ratios when comparedbetween nonlesion and lesion sites in the ribs.Discussion:The increase inδ15N seen in active lesions, when compared withδ15Nfrom nonlesion regions on the same long bone, may be a consequence of altered pro-tein metabolism. The high variability ofδ15N andδ13C in fractures may be related todifferent healing stages of the calluses. This study suggests that stable isotope datacan contribute information about diseases in the past, as well as an individual'sresponse to diseases in the absence of modern medicine and antibiotics.