Abstract
The assessment of the vitamin K status and its effects on clinical outcomes in kidney transplantation (KT) patients has sparked interest, but it is still largely unfulfilled. In part, this is due to difficulties in laboratory measurements of vitamin K, especially K2 vitamers. Vitamin K status is currently best assessed by measuring undercarboxylated vitamin-K-dependent proteins. The relative contribution of vitamin K1 and K2 to the health status of the general population and CKD (chronic kidney disease) patients, including KT patients, is also poorly studied. Through a complete and first review of the existing literature, we summarize the current knowledge of vitamin K pathophysiology and its potential role in preventing KT complications and improving organ survival. A specific focus is placed on cardiovascular complications, bone fractures, and the relationship between vitamin K and cancer. Vitamin K deficiency could determine adverse outcomes, and KT patients should be better studied for vitamin K assessment and modalities of effective therapeutic approaches.
Highlights
Kidney transplantation (KT) has several significant benefits compared to dialysis treatment, such as a better quality of life, prolonged survival, and lower costs [1]
Among the causes of vitamin K deficiency in chronic kidney disease (CKD) patients, the following are more common—dietary restrictions determining inadequate intake; dysbiosis due to the uremic condition that leads to a decreased vitamin K; production by microbiota; and hemodialysis associated deficits [8,22,23]
In a secondary analysis of the VItamin K Italian (VIKI) study, we found that calcimimetics and vitamin D analogs might play a role in preserving Vitamin-K-Dependent Proteins (VKDPs) activity
Summary
Kidney transplantation (KT) has several significant benefits compared to dialysis treatment, such as a better quality of life, prolonged survival, and lower costs [1]. Several factors can influence vitamin K status in CKD patients, either reducing or enhancing its activity (Table 2). Among the causes of vitamin K deficiency in CKD patients, the following are more common—dietary restrictions determining inadequate intake; dysbiosis due to the uremic condition that leads to a decreased vitamin K (especially long-chain MKs); production by microbiota; and hemodialysis associated deficits [8,22,23]. Warfarin use interferes with vitamin K recycling, reducing γ-carboxylation, and the activity of VKDPs. warfarin-treated patients develop vitamin K deficiency, associated with a high prevalence of VCs, VFs (in males), and mortality, both in the general population [27,28] and in CKD patients [29,30]. A recent prospective study of 34 patients assessed changes in VKDPs during the 1st year of KT, showing a decrease in the undercarboxylated (inactive form) amount [33]
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