Abstract: TH-PO1037

Hidden Hypocalcemia at the Initiation of Dialysis

Session Information

Category: Mineral Disease

  • 1201 Mineral Disease: Ca/Mg/PO4

Authors

  • Yamaguchi, Satoshi, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Isaka, Yoshitaka, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Hamano, Takayuki, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Shimada, Karin, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Matsumoto, Ayumi, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Hashimoto, Nobuhiro, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Oka, Tatsufumi, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Mori, Daisuke, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Sakaguchi, Yusuke, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
  • Matsui, Isao, Osaka Univ Graduate School of Medicine, Suita, Osaka, Japan
Background

Hypocalcemia (HypoCa) often leads to arrhythmia and heart failure. Our aims of this study are to reveal serum calcium abnormalities in incident hemodialysis (HD) patients and its clinical significance.

Methods

We performed a retrospective cohort study of incident HD patients. We collected the latest data just before the initiation of HD. We used logistic regression models to examine the factors associated with true HypoCa defined as ionized Ca (iCa) <1.15 mmol/L. We performed analyses to explore the association between the iCa levels and QTc prolongation in electrocardiogram, which was reported to be a predictor of cardiovascular death in CKD. Restricted cubic spline analyses were employed to explore potential nonlinear relationships between iCa and ALP or intact PTH (iPTH) levels.

Results

Among the enrolled 336 patients, the mean (SD) eGFR was 5.1 (1.9) mL/min/1.73m2. Eighty-one % of the patients showed true HypoCa, 60 % of whom showed normal corrected Ca (cCa), in other words, hidden HypoCa. Among patients with normal cCa levels, the ALP levels greater than upper normal limit were significantly associated with hidden HypoCa (Odds ratio; 8.4, 95%CI 1.1~64), accounting for 75% of normal cCa. Multivariate analysis showed the significant factors associated with true HypoCa were male, lower eGFR and serum albumin levels, higher serum phosphate levels, non-use of active vitamin D in pre-dialysis CKD, polycystic kidney disease, and high BNP levels (Fig.1). Moreover, lower iCa levels were associated with higher prevalence of QTc prolongation. A negative association between iCa and ALP were observed. Additional adjustment for iPTH did not change the relationship between iCa and ALP substantially (Fig.1), implying that osteomalacia induced by low iCa levels might explain high ALP levels.

Conclusion

Hidden HypoCa was prevalent just before the start of HD and associated with high ALP and BNP levels accompanied by QTc prolongation. High ALP levels despite normal cCa imply the presence of hidden HypoCa. The impact of pre-dialysis HypoCa on hard outcomes after HD initiation remains to be elucidated.