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Abstract: TH-PO579

Hyperparathyroidism Helps to Explain the Disagreement Between Bioimpedance and Dual-Energy Absorptiometry in the Analysis of Nutritional Status

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Crispilho, Shirley Ferraz, Universidade Nove de Julho, São Paulo, Brazil
  • de Sa C. Filho, Eduardo J. Duque, Universidade de Sao Paulo, Brazil, SÃO PAULO, Brazil
  • Bezerra de carvalho, Kalyanna Soares, Universidade de Sao Paulo, Brazil, SÃO PAULO, Brazil
  • Pereira, Rosa M., Universidade de Sao Paulo, Brazil, SÃO PAULO, Brazil
  • Jorgetti, Vanda, Universidade de Sao Paulo, Brazil, SÃO PAULO, Brazil
  • Elias, Rosilene M., Universidade de Sao Paulo, Brazil, Brazil
  • Moyses, Rosa M.A., Universidade de Sao Paulo, Brazil, SÃO PAULO, Brazil
Background

Body composition is critical in the evaluation of patients with CKD and can be obtained from multifrequency bioelectrical impedance analysis (BIA) or from the gold standard dual-energy absorptiometry (DXA). Previous studies have shown disagreements between these two methods, mainly regarding the bone mineral content (BMC). We hypothesized that secondary hyperparathyroidism, which is associated with bone loss, is the main responsible for this discrepancy.

Methods

We studied 20 pre-dialysis CKD patients (CKD) and 29 on hemodialysis (18 with severe hyperparathyroidism (HD-SHPT) and 11 already submitted to parathyroidectomy at least 1 year before our analysis (HD-PTX). The total-body composition was determined using DXA and BIA.

Results

HD-SHPT patients tended to be younger (CKD = 52.5 ± 14.3 ys.; HD-SHPT = 41.6 ± 14.9 ys.; HD-PTX 44.9 ± 13.4 ys.; p = 0.06), but had lower BMC measured through DXA (CKD = 2,266 ± 565 g; HD-SHPT = 1,808 ± 522 g; HD-PTX 2,301 ± 658 g; p = 0.04). This difference was not found in BMC measured by BIA (CKD = 3,011 ± 596 g; HD-SHPT = 2,896 ± 711 g; HD-PTX 2,650 ± 467 g; p = 0.30).The highest disagreement between DXA and BIA was found in HD-SHPT group (CKD = -711 g; HD-SHPT = - 915 g; HD-PTX -688 g; p = 0.004). There was a significant correlation between the difference of BMC obtained from DXA and BIA with parathormone (PTH; r = -0.394; p = 0.006) and alkaline phosphatase (AP; r = -0.489; p < 0.0001).

Conclusion

Our results confirm that BIA should be interpreted cautiously in patients with SHPT since higher PTH and AP lead to a greater disagreement between these methods. Moreover, the recovery of bone mass and the decrease of the disagreement after PTX support our hypothesis. BIA loss of accuracy occurs because BMC is not measured, but obtained from an algorithm derived from normal individuals, using the fat-free mass values. Therefore, BMC overestimation is associated with an underestimation of lean mass. This misinterpretation might compromise the management of the nutritional status, as well as of the bone disease, in SHPT patients.

Funding

  • Government Support - Non-U.S.