Vitamin D testers have different test results if there is chronic kidney disease

Created December 2019

Chronic kidney disease is a main confounding factor for 25-vitamin D measurement

J Bras Nefrol. 2019 Sep 26. doi: 10.1590/2175-8239-JBN-2019-0053.

Hanna Karla Andrade Guapyassú Machado, Carolina Steller Wagner Martins, Vanda Jorgetti, Rosilene Motta Elias, Rosa Maria Affonso Moysés

Jornal Brasileiro de Nefrologia: ʹorgão Oficial de Sociedades Brasileira e Latino-Americana de Nefrologia

The founder of VitaminDWiki does not recall seeing this before * More than 30 ng of vitamin D is sometimes needed (Kidney needs 50 ng) – March 2019 * 1 in 10 have Chronic Kidney Disease (but only 5% are aware of it) – review Sept 2019 * Tests for Vitamin D --- Items in both categories Kidney Disease and Vitamin D Test are listed here: {category} --- 1. [Not a single citation of this study was made as of Feb 2021](https://scholar.google.com/scholar?hl=en&as;_sdt=0%2C48&q;=%22Chronic+kidney+disease+is+a+main+confounding+factor+for+25-vitamin+D+measurement%22&btnG;=) This is a strong hint that the study was not believed

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BACKGROUND: Current guidelines recommend assessment of 25-vitamin D status in patients with chronic kidney disease (CKD). Although significant differences among assays have been described, the impact of CKD on this variability has never been tested.

METHODS: We tested the variability between two 25-vitamin D assays in patients with CKD (eGFR < 60 mL/min/1.73m2) who had consecutive 25-vitamin D measurements in 2015 (

  • Assay 1 - Diasorin LIASON 25 TOTAL - D assay®) and 2016 (

  • Assay 2 - Beckman Coulter Unicel Xl 800®).

The cohort consisted of 791 adult patients (122 with normal renal function and 669 with CKD - 33, 30, and 37% in stages 3, 4, and 5 on dialysis, respectively).

RESULTS: Levels of 25-vitamin D were lower and the prevalence of hypovitaminosis D using assay 1 was higher than using assay 2 in patients with CKD, regardless of similar levels of calcium, phosphate, and parathyroid hormone. As kidney function decreased, the percentage of disagreement between the assays increased.

CONCLUSION: There is a noteworthy variability between assays in patients with CKD such that the diagnosis of hypovitaminosis D is modified. The mechanism behind this result is still unclear and might be due to a possible interference in the analytical process. However, the clinical significance is unquestionable, as the supplementation of vitamin D can be erroneously prescribed to these patients.

Tags: Kidney Tests