Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Zajic, P.
Diagnosis of Vitamin D Deficiency in Critical Care.
Doktoratsstudium der Medizinischen Wissenschaft; Humanmedizin; [ Dissertation ] Graz Medical University; 2020. pp. 112
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Amrein Karin
- Fruhwald Sonja
- Toller Wolfgang
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- Abstract:
- Introduction: Vitamin D deficiency is common in critically ill patients; yet there is uncertainty how acute illness and its treatment affect levels and how vitamin D should best be measured in critically ill patients. This study therefore sought to assess the influence of fluid loading and inflammation on 25-hydroxy-vitamin D [25(OH)D] and 1,25-diyhydroxy-vitamin D [1,25(OH)2D] levels using a readily available chemi-luminescence assay (ECLIA, IDS-iSYS) and the presumed gold standard of liquid chromatography / mass spectrometry (LC-MS/MS) for diagnosis of vitamin D deficiency perioperatively and during intensive care. Materials and Methods: A prospective, observational pilot study in adult patients undergoing cardiovascular surgery on cardiopulmonary bypass (CPB) was conducted. Blood samples drawn at preoperative baseline (t1), after weaning from CPB (t2) and at intensive care unit (ICU) admission (t3) were analysed in a “perioperative phase” cohort, further samples were collected on the first (t4) and second (t5) postoperative day and analysed in a “critical care phase” patient cohort. Results – Findings: 66 patients were included in the “perioperative phase”, 26 of these were included in the “critical care phase”. Fluid loading by CPB led to a median 25(OH)D reduction of 23% (p<0.001) between t1 and t2 with recovery towards t5, while 1,25(OH)2D levels were reduced by 55% (p<0.001) and did not recover during the observation period. Mean difference between 25(OH)D measurements by ECLIA and LC-MS/MS was 4.8ng/ml (±5.7). Pearson’s r for correlation of these measurements was 0.73 (p<0.001). LC-MS/MS results for 25(OH)D were not influenced by the inactive C3-epimer. Discussion: Vitamin D can indeed be considered a “negative acute-phase reactant”; its levels are significantly altered by fluid loading and inflammation. 25(OH)D measurements using chemiluminescence assays may be notably different from LC-MS/MS, which can be considered the gold standard for measurements in this patient group. Stricter definitions of vitamin D deficiency than in the normal population, such as serum levels of 25(OH)D below 12ng/ml, may be better suited for the diagnosis of vitamin D deficiency in critically ill patients with a low false-positive rate.