Reply to Janssen et al. Comment on “Kremer et al. Kidney Function-Dependence of Vitamin K-Status Parameters: Results from the TransplantLines Biobank and Cohort Studies. Nutrients 2021, 13, 3069”

• Published in: Nutrients Vol. 14; no. 12; p. 2440
• Main Authors: Kremer, Daan, Groothof, Dion, Keyzer, Charlotte A., Eelderink, Coby, Knobbe, Tim J., Post, Adrian, van Londen, Marco, Eisenga, Michele F., TransplantLines Investigators, Schurgers, Leon J., Berger, Stefan P., de Borst, Martin H., Bakker, Stephan J. L.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 13.06.2022; MDPI
• Subjects: Biobanks; Cohort analysis; cohort studies; Creatinine; Intervention; Kidney diseases; Kidney transplants; kidneys; nutrients; Plasma; Proteins; Reply; vitamins
• ISSN: 2072-6643; 2072-6643
• DOI: 10.3390/nu14122440

Importantly, with a molecular mass similar to the emerging glomerular filtration marker cystatin C, and the absence of material renal excretion, which is also quite similar to the behavior of cystatin C, MGP is likely subject to glomerular filtration, followed by tubular uptake and further catabolism without tubular secretion, much like cystatin C [3,4]. Undoubtedly, such a plot would have been supportive of the conclusion regarding the kidney function-dependence of circulating MGP concentrations. [...]we would like to highlight that in their comment, Janssen et al. only refer to the cross-sectional analyses of our study, which show that kidney function parameters are strongly associated with dp-ucMGP. [...]we disagree with the statement in the comment by Janssen et al. that the correlation between dp-ucMGP and creatinine is “far more likely the result of vitamin K deficiency than a function of decreased glomerular filtration rate”.