UC San Diego

Bone marrow adiposity is associated with aging, osteoporosis, and reduced hematopoiesis, as well as anorexia nervosa, but little is known about the underlying mechanisms that affect marrow adiposity. Chronic kidney disease (CKD) may influence bone marrow adipose tissue (BMAT), possibly through loss of lean mass or higher circulating levels of sclerostin. To test these hypotheses, we investigated the cross-sectional association between estimated glomerular filtration rate (eGFR) as a measure of kidney function and ¹ H-MRS-based measurement of vertebral BMAT (L1 to L4) in 475 older adults from the Age Gene/Environment Susceptibility (AGES)-Reykjavik study. Mean BMAT was compared in those with eGFR >60 (n = 297) versus those with eGFR 45 to 60 (n = 120) or eGFR <45 (n = 58) using linear regression models. Participants had a mean age of 81.5 (SD 4.1) years, mean eGFR of 64.3 (SD 16.1) mL/min/1.734 cm² , mean BMAT of 54.5% (SD 8.5); 48.2% were women. In unadjusted and adjusted models (age, visit window, gender, diabetes and visceral adipose tissue), BMAT was higher in those with eGFR <45 (adjusted mean 58.5%; 95% CI, 56.2 to 60.7) compared with those with eGFR >60 (adjusted mean 53.8%; 95% CI, 52.8 to 54.8) (p = 0.0002). BMAT did not differ in those with eGFR 45 to 60 (adjusted mean 54.3%; 95% CI, 52.8 to 55.9) compared with those with eGFR >60 (p = 0.58). In a subgroup of participants with serum sclerostin available (n = 253), additional adjustment for sclerostin attenuated the difference in adjusted mean vertebral BMAT between those with eGFR <45 versus >60 from 3.7% (p = 0.04) to 2.4% (p = 0.20). CKD stage 3b or worse was associated with greater bone marrow adiposity; this association may be partially mediated by sclerostin. © 2018 American Society for Bone and Mineral Research.