Bone marrow fat is increased in chronic kidney disease by magnetic resonance spectroscopy

Abstract

Summary In aging, the bone marrow fills with fat and this may lead to higher fracture risk. We show that a bone marrow fat measurement by magnetic resonance spectroscopy (MRS), a newer technique not previously studied in chronic kidney disease (CKD), is useful and reproducible. CKD patients have significantly higher bone marrow fat than healthy adults. Introduction Renal osteodystrophy leads to increased morbidity and mortality in patients with CKD. Traditional bone biopsy histomorphometry is used to study abnormalities in CKD, but the bone marrow, the source of osteoblasts, has not been well characterized in patients with CKD. Methods To determine the repeatability of bone marrow fat fraction assessment by MRS and water-fat imaging (WFI) at four sites in patients with CKD, testing was performed to determine the coefficients of reproducibility and intraclass coefficients (ICCs). We further determined if this noninvasive technique could be used to determine if there are differences in the percent bone marrow fat in patients with CKD compared to matched controls using paired t tests. Results The mean age of subjects with CKD was 59.8±7.2 years, and the mean eGFR was 24±8 ml/min. MRS showed good reproducibility at all sites in subjects with CKD and controls, with a coefficient of reproducibilities ranging from 2.4 to 13 %. MRS and WFI assessment of bone marrow fat showed moderate to strong agreement (ICC 0.6–0.7) at the lumbar spine, with poorer agreement at the iliac crest and no agreement at the tibia. The mean percent bone marrow fat at L2–L4 was 13.8 % (95 % CI 8.3–19.7) higher in CKD versus controls (p<0.05). Conclusions MRS is a useful and reproducible technique to study bone marrow fat in CKD. Patients with CKD have significantly higher bone marrow fat than healthy adults; the relationship with bone changes requires further analyses.

The Role of Bone Marrow Fat in Skeletal Health: Usefulness and Perspectives for Clinicians

“….) and chronic kidney disease (85), in which BMF abnormalities have been demonstrated. In daily practice, the usefulness for clinicians of assessing BMF using MRI is still limited, but perspectives are exciting, particularly in terms of improving the diagnosis and management of osteoporosis.…”

Chronic Kidney Disease Is Associated With Greater Bone Marrow Adiposity

“…(3) Those with CKD (mean eGFR 24 mL/min/1.734cm 2 ) had 13.8% higher (L2 to L4) vBMAT compared with the control group. (3) Participants in our study with eGFR <45 (mean eGFR 35 mL/min/1.734cm 2 ) had a mean (L1 to L4) vBMAT of 58.5%, which is similar to that reported in the 8 CKD subjects (57.8% at L2, 56.9% at L3, and 59.8% at L4). The magnitude of difference in vBMAT between the CKD subjects and controls was greater (13.8%) than the difference we observed (4.9%).…”

“…One previous study reported higher vertebral BMAT (vBMAT) in those with chronic kidney disease (CKD) compared with age-matched healthy controls. (3) However, this study had a small sample size ( n = 16) and did not include a full range of kidney function. The primary goal of the current study was to determine if impaired kidney function is associated with vBMAT in older adults enrolled in the Age Gene/Environment Susceptibility (AGES)-Reykjavik study.…”

Low Bone Turnover in Chronic Kidney Disease Is Associated with Decreased VEGF-A Expression and Osteoblast Differentiation

“…In BM-derived MSC, there is a progressive increase in adipocyte formation and a decrease in osteoblast number with aging [34] . We have also demonstrated increased BM fat in patients with CKD compared to healthy age-, gender-and race-matched individuals [10] . Older individuals have reduced BFRs and a high fat to bone ratio in their BMs compared with young and healthy controls [35], suggesting that the control of the fates of osteoblast/adipocyte differentiation in BM MSC is important in bone formation, similar to the findings in the CKD animals in the present study.…”

“…With aging [9] , and in CKD [10] , MSC preferentially differentiate to adipocytes rather than osteoblasts, leading to increased marrow fat and low BFRs. One regulator of normal osteoblast differentiation is vascular endothelial growth factor-A (VEGF-A) [11] .…”