No difference in sex, indoor or outdoor working, diabetes mellitus, estimated creatinine clearance, hypocalcemia, hyperphosphatemia, and hyperparathyroidism between two groups of decreased and normal serum 1.25-dihydroxycholecalciferol. Conclusion: Serum 1.25-dihydroxycholecalciferol decreased in 82% predialysis ESRD patients.