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Endocrine Abstracts (2020) 70 AEP150 | DOI: 10.1530/endoabs.70.AEP150

ECE2020 Audio ePoster Presentations Bone and Calcium (121 abstracts)

Analysis of 25OHD levels in chronic renal failure depending on the methods

Erzsébet Toldy 1,2,3 , Judit Konderak 1 , László Kovács 4,5 , Ágnes Tüttő 3 , Gellért Balázs Karvaly 6 & Zoltán Lőcsei 4

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1Budapest, SYNLAB Hungary Ltd., Budapest, Hungary, Diagnostic Centre Clinical Chemistry and Immunology Laboratories, Budapest, Hungary; 2Szeged QualiCont In Vitro Diagnostic Quality Control Nonprofit Ltd., Szeged, Hungary; 3Pécs University of Pécs Faculty of Health Science, Institute of Diagnostics, Pécs, Hungary; 4Szombathely Markusovszky University Teaching Hospital, Department of General Internal Medicine, Szombathely, Hungary; 5Szombathely, B. Braun Avitum Hungary Dialysis Center No 6, Szombathely, Hungary; 6Budapest, Faculty of Medicine, Institute of Laboratory Medicine, Semmelweis University, Budapest, Hungary


Vitamin D deficiency is common in patients with chronic renal failure (CRF) based on routinely determined total-25-hydroxyvitaminD (t-25OHD) levels. The present knowledge is contradictory whether the direct measured free-25OHD (dm_f-25OHD) or the calculated free-25OHD (c_f-25OHD) is the best indicator of the vitamin D supply for CRF patients. Adding methods to our previously described first experiences on this subject, in this study we aimed to serve newer data to make this question clearer.

Method: 95 patients [39 men; 56 women; 69 ± 12 years: 30 on peritoneal dialysis (PD) 34 on haemodialysis (HD), both on 3000 IU D3/day; 31 pre-dialysis (preD) on 1400 IU D3/day] were investigated. Their sera were analysed for vitamin D-binding protein (DBP) (Dako), albumin (immunoturbidimetry, Integra), Ca, PTHi (Roche) dm_f-25OHD (ELISA, FutureDiagnostics), t-25OHD [using two methods: liquid chromatography/mass spectrometry (t-25OHD_MS) and chemiluminescence immunoassay (t-25OHD_CLIA; DiaSorin]. The c_f-25OHD levels were calculated from both t-25OHD (c_f-25OHD_MS; c_f-25OHD_CLIA). Differences between the methods were evaluated by Passing&Bablok regression and Bland & Altman analysis.

Results: Albumin levels were the lowest (PD:33 ± 4 vs HD:37 ± 4; preD:39 ± 4 g/l; P < 0,001) and DBP concentrations the highest (PD:351 ± 39 vs HD:307 ± 48 mg/l; P < 0,001) in PD group. The t-25OHD_CLIA levelswere lower compared to t-25OHD_MS t-(73.4 ± 22.4 vs 106.2 ± 30.5 nmol/l; P < 0,0001) in all groups, but the greatest bias was in PD patients (37%; test of linearity: P = 0.660). Free 25OHD levels obtained by calculation were overestimated compared to dm_f-25OHD concentrations in all three groups (all groups: dm_f-25OHD: 13.2 ± 4.5 vs c_f-25OHD_MS: 26.4 ± 11.4 and c_f-25OHD_CLIA: 20.0 ± 8.2 pmol/l; P < 0.001). The negative biases were significantly higher in case of c_f-25OHD_MS in all groups compared to c_f-25OHD_CLIA (preD: −53% vs −35,2%; PD: −67% vs −31%; HD: −45% vs −66%) but the test of linearity showed the best correlation between direct measured and c_f-25OHD_MS in PD (P = 0,999). All 25OHD fractions were significantly lower (P < 0,010) in PD compared to HD (t-25OHD_CLIA:73.4 vs 94.8 nmol/l; t-25OHD_MS:106 vs 122 nmol/l; dm-f-25OHD: 11.9 vs 14.9 pmol/l; c_f-25OHD_CLIA:24.2 vs 31.3 pmol/l) though the patients received the same dose of vitamin D3. Out of the five obtained 25OHD levels only dm_f-25OHD showed significant positive correlation (r = 0.39) with Ca and only in preD patients.

Conclusions: Our results highlight that determination of cut-off values that reflect the appropriate vitamin D supply should be defined according to the diseases and the methods as well. Calculated free levels overestimate the 25OHD supply. The dm_f-25OHD promises to be the most reliable marker in preD. All five methods certify that patients on PD need much higher doses of cholecalciferol.

Volume 70

22nd European Congress of Endocrinology

Online
05 Sep 2020 - 09 Sep 2020

European Society of Endocrinology 

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