Introduction:
Older adults with chronic kidney disease (CKD) can have low bone mineral density (BMD) with concurrent vascular calcification. It is not known if mineral accrual by the growing skeleton protects young people with CKD from extraosseous calcification. My hypothesis was that children and young adults with increasing BMD do not develop vascular calcification.
Methods:
Multicentre longitudinal study in children and young people (5-30 years) with CKD stages 4-5 or on dialysis. Cortical (Cort) and trabecular (Trab) BMD were assessed by peripheral quantitative Computed Tomography and lumbar spine BMD by DXA (Dual Energy X-ray Absorptiometry). Vascular calcification was assessed by cardiac CT for coronary artery calcification (CAC) and ultrasound for carotid intima-media thickness (cIMT). Arterial stiffness was measured by pulse wave velocity (PWV) and carotid distensibility.
Results:
One hundred participants (median age 13.82 years) were assessed at baseline and 57 followed-up after a median of 1.45 years. The cohort had a significant bone and cardiovascular disease burden. 10% suffered at least one previous atraumatic fracture, and 58% reported bone pain affecting activities of daily living. The majority had evidence of vascular calcification and arterial stiffness with increased cIMT and PWV z-scores. 10% had CAC at baseline. Baseline TrabBMD was independently associated with cIMT (R2=0.10, β=0.34, p=0.001). An annualised increase in TrabBMD was an independent predictor of cIMT increase (R2=0.48, β=0.40, p=0.03), with 6-fold greater odds of an increase in ΔcIMT in those with an increase in ΔTrabBMD [(95%CI 1.88 to 18.35), p=0.003]. Young people that demonstrated statural growth (n=33) had attenuated vascular changes compared to those with static growth.
Conclusion:
These hypothesis generating studies suggest that children and young adults with CKD or on dialysis may develop vascular calcification even as BMD increases. A presumed buffering capacity of the growing skeleton may offer some protection against extraskeletal calcification.