A cross-sectional study measuring vanadium and chromium levels in paediatric patients with CKD

Abstract

Objectives: Although many secondary effects of high levels of vanadium (V) and chromium (Cr) overlap with symptoms seen in paediatric patients with chronic kidney disease (CKD), their plasma V and Cr levels are understudied.

Design: Ancillary cross-sectional study to a prospective, longitudinal, randomised controlled trial.

Setting: Children's Hospital of Western Ontario, London Health Sciences Centre, London, Ontario, Canada.

Participants: 36 children and adolescents 4-18 years of age with CKD.

Interventions: 1-6 trace element measurements per patient. Cystatin C (CysC) estimated glomerular filtration rate (eGFR) was calculated using the Filler formula. Plasma V and Cr levels were measured using high-resolution sector field inductively coupled mass spectrometry. Anthropomorphic data and blood parameters were collected from our electronic chart programme. Water Cr and V data were obtained from the Ontario Water (Stream) Quality Monitoring Network.

Primary and secondary outcome measures: Primary outcomes: plasma Cr and V.

Secondary outcomes: age, season, CysC, CysC eGFR, and Cr and V levels in environmental water.

Results: The median (IQR) eGFR was 51 mL/min/1.73 m2 (35, 75). The median V level was 0.12 µg/L (0.09, 0.18), which was significantly greater than the 97.5th percentile of the reference interval of 0.088 µg/L; 32 patients had at least one set of V levels above the published reference interval. The median Cr level was 0.43 µg/L (0.36, 0.54), which was also significantly greater than the established reference interval; 34 had at least one set of Cr levels above the published reference interval. V and Cr levels were moderately correlated. Only some patients had high environmental exposure.

Conclusions: Our study suggests that paediatric patients with CKD have elevated plasma levels of V and Cr. This may be the result of both environmental exposure and a low eGFR. It may be necessary to monitor V and Cr levels in patients with an eGFR <30 mL/min/1.73 m2.

Trial registration number: NCT02126293; HC#172241.

Keywords: Chronic renal failure; Environmental Impact on Health; PUBLIC HEALTH; Paediatric nephrology; TOXICOLOGY.

Conflict of interest statement

Competing interests: None declared.

© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Figures

Figure 1

Patient flow chart. Of the 38 subjects assessed for eligibility in the study, we included 36 in our analysis. These 36 patients had 94 trace element panel measurements. CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate.

Figure 2

Scatter plot of vanadium levels versus estimated glomerular filtration rate (eGFR). Vanadium levels (μg/L) were not normally distributed. The non-linear regression line (one-phase exponential decay) has been included. Glomerular filtration rate was measured in mL/min/1.73 m2. The formula reads: Y=(Y0−Plateau)×exp(−K×x)+Plateau, where Y0 is the value when x is 0, plateau is Y at a large value, K is the rate constant, and the values were Y0=4.555, Plateau=0.1457 and K=0.1111 (GraphPad Prism).

Figure 3

Repeated measures plot of first and last vanadium level in those patients who had repeated levels. Vanadium levels (μg/L) were not normally distributed. While the median vanadium level lowered from 0.1510 to 0.1410 µg/L, and many patients demonstrated an increase of their vanadium level with repeated measures, this did not reach statistical significance (p=0.4140, Wilcoxon matched-pairs signed-rank test).

Figure 4

Scatter plot of chromium levels versus estimated glomerular filtration rate (eGFR). Chromium levels (μg/L) were not normally distributed. The non-linear regression line (one-phase exponential decay) has been included. Glomerular filtration rate was measured in mL/min/1.73 m2. The formula reads: Y=(Y0−Plateau)×exp(−K×x)+Plateau, where Y0 is the value when x is 0, Plateau is Y at a large value, K is the rate constant, and the values were Y0=1.641, Plateau=0.4841 and K=0.09060 (GraphPad Prism).

Figure 5

Repeated measures plot of first and last chromium level in those patients who had repeated levels. Chromium levels (μg/L) were not normally distributed. The median chromium level did not change from 0.44 µg/L and the rise in the values was not statistically significant (p=0.3381, Wilcoxon matched-pairs signed-rank test).

Figure 6

Heat map showing the concentration of vanadium in 2014 in various streams around Southwestern Ontario. Map created using 2014 data from the Provincial (Stream) Water Quality Monitoring Network at https://www.ontario.ca/data/provincial-stream-water-quality-monitoring-network in open-source software found at www.openheatmap.com.

Figure 7

Heat map showing the concentration of chromium in 2014 in various streams around Southwestern Ontario. Map created using 2014 data from the Provincial (Stream) Water Quality Monitoring Network at https://www.ontario.ca/data/provincial-stream-water-quality-monitoring-network in open-source software found at www.openheatmap.com.