Naturally occurring stable calcium isotope ratios are a novel biomarker of bone calcium balance in chronic kidney disease

Bone Mineral Density and Vascular Calcification in Children and Young Adults With CKD 4 to 5 or on Dialysis

“… 41 This work has been extended to children with CKD and on dialysis in whom δ 44/42 Ca serum values were the strongest predictor of total bone mineral content. 42 …”

Renal osteodystrophy: A historical review of its origins and conceptual evolution

“…Dual calcium isotope methodologies have been utilized to quantify these fluxes and bone balance in response to therapeutic interventions but are expensive and involve clinical research center testing ( Hill et al, 2013 ; Hill Gallant et al, n.d. ). More recently advances in mass spectrometry have allowed the assessment of naturally occurring (in food and bone) stable calcium isotopes, allowing the development of techniques to assess bone balance from blood or urine samples ( Shroff et al, 2021 ; Shroff et al, 2022 ). The possibility of measuring real time changes will almost certainly advance knowledge of the role of bone in normal mineral homeostasis.…”

Natural stable calcium isotope ratios: a new gold standard for bone balance?

“…Shroff et al 2 utilized the natural stable calcium isotope ratio (expressed as d 44/42 Ca) measured in serum and urine in children with CKD stage 4-5 or receiving dialysis to assess its potential as a biomarker of bone calcium balance in this population. The authors found that d 44/42 Ca serum was positively correlated with bone mineral density and BMC measures from DXA and peripheral quantitative computed tomography (pQCT) in dialysis patients (but not children with CKD stage 4-5), as well as the traditional bone formation marker, serum total alkaline phosphatase, and inversely correlated with traditional markers of bone resorption, serum parathyroid hormone, tartrate-resistant c o m m e n t a r y acid phosphatase 5b, and C-terminal telopeptide of type I collagen.…”

“…see clinical investigation on page 624 E stimated glomerular filtration rate (eGFR) has substantial heritability in family-based studies, and genetic contributions to the risk of chronic kidney disease (CKD) are well established. 1,2 Prior genome-wide association studies (GWAS) have identified hundreds of loci associated with crosssectional creatinine (Cr)-based eGFR. 3,4 However, a single time point Cr-based eGFR may be influenced by several nonrenal and nongenetic factors, such as age, sex, muscle mass, rates of Cr metabolism, or transient changes in Cr clearance due to volume depletion, illness, or medications.…”