Bone microarchitecture using HR-pQCT in adult patients with renal tubular acidosis presenting with rickets/osteomalacia.

UNLABELLED: Adults with renal tubular acidosis (RTA) show high bone turnover, reduced trabecular volumetric bone mineral density (vBMD), and compromised bone microarchitecture, especially in trabecular bone. HR-pQCT analysis reveals lower total vBMD, reduced trabecular number, increased separation, and cortical thinning, highlighting bone deterioration in RTA patients compared to controls.

BACKGROUND

Renal tubular acidosis (RTA) impairs urinary acidification, leading to a normal anion gap metabolic acidosis and often hypokalemia. RTA can result in poor bone mineralization and reduced bone density in adults. This study aims to evaluate bone microarchitecture in adults with RTA using second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT).

METHODS

In this cross-sectional case-control study, 12 adult RTA patients with rickets/osteomalacia and 12 age, sex, and BMI-matched controls were enrolled. Clinical assessments, biochemical tests with calcium, phosphate, alkaline phosphatase, 25(OH)D, intact PTH, bone turnover markers, dual-energy X-ray absorptiometry (DXA), and HR-pQCT scans were conducted.

RESULTS

Patients with RTA had increased bone turnover compared to the controls. RTA patients had significantly lower total hip areal bone mineral density (aBMD) [g/cm2] (median, 0.792 vs. 0.943; p = 0.014) and lower distal radius aBMD [g/cm2] (median, 0.469 vs. 0.694, p 0.000), compared to controls. HR-pQCT findings suggest lower total and trabecular volumetric BMD (v.BMD), at both the radius (median total vBMD [mg HA/cm3]: 236 vs. 380.1, p = 0.001; median trabecular vBMD [mg HA/cm3]; 83.4 vs. 170.1, p = 0.000) and tibia (median total vBMD [mg HA/cm3]: 222.1 vs. 317.4, p = 0.000; median trabecular vBMD [mg HA/cm3]: 69.0 vs. 160.9, p = 0.000) in RTA patients compared to controls. Cortical vBMD was comparable between groups. Microarchitecture analysis revealed reduced trabecular number, increased trabecular separation, increased trabecular bone inhomogeneity, and reduced cortical thickness in RTA patients, both at radius and tibia.

CONCLUSION

Adults with RTA exhibit high bone turnover, reduced trabecular vBMD, and compromised bone microarchitecture, particularly in trabecular bone.