Early Secondary Hyperparathyroidism and the Evolving Spectrum of Mineral and Bone Disorder in Chronic Kidney Disease: A Single-Centre Experience From Central India

Background: Chronic kidney disease-mineral and bone disorder (CKD-MBD) is characterised by disturbances of calcium, phosphate and parathyroid hormone metabolism, and may be accompanied by vascular and valvular calcification. We set out to characterise stage-associated differences in these abnormalities in a Central Indian cohort, a setting for which region-specific data remain limited. Methodology: In this retrospective, cross-sectional single-centre study, we reviewed the records of 150 consecutive patients with CKD stages 3-5D managed at a tertiary care centre in Central India between May 2024 and April 2025. Demographic, clinical and biochemical variables - albumin-corrected calcium, phosphorus, alkaline phosphatase (ALP), intact parathyroid hormone (iPTH) and 25-hydroxyvitamin D - were extracted, together with radiological assessment of vascular calcification by lateral abdominal radiography and of valvular calcification by echocardiography in patients with complete imaging records (n = 57). The stage-wise prevalence of each abnormality was determined and its relationship with calcification examined. Results: Secondary hyperparathyroidism was the earliest and most consistent abnormality, present in 11 (45.8%) of stage 3 patients and rising to 50 (90.9%) by stage 5. Among dialysis-dependent (stage 5D) patients, the pattern broadened, with 11 (44.0%) showing elevated iPTH and 9 (36.0%) showing suppressed iPTH, suggestive of low bone turnover. Hypocalcaemia and hyperphosphataemia were uncommon in stages 3-4 but affected 25 (45.5%) and 33 (60.0%) patients, respectively, at stage 5 and 14 (56.0%) and 19 (76.0%) patients, respectively, at stage 5D, while the rise in ALP paralleled that of iPTH, consistent with increased bone turnover. Vitamin D deficiency was highly prevalent throughout (58%-80%) and showed no clear stage gradient. Vascular calcification increased from none in stage 3 to 5 (55.6%) in stage 5D, and valvular calcification from none to 2 (22.2%). Calcification was associated with higher phosphorus and iPTH and lower corrected calcium, but not with vitamin D status. Conclusions: In this Central Indian cohort, CKD-MBD showed a coherent stage-associated pattern: early secondary hyperparathyroidism from stage 3, more frequent mineral derangement at advanced stages, and vascular and valvular calcification in advanced disease. While this pattern mirrors international observations, the high background burden of vitamin D deficiency and the frequency of late presentation lend a distinct regional character to the disorder. The findings support early and serial biochemical monitoring from stage 3, with stage-specific, individualised intervention aimed at limiting cardiovascular risk.