Patients with chronic kidney disease (CKD) suffer disproportionately from a high burden of cardiovascular disease, which, despite recent scientific advances, remains partly understood. Vascular calcification (VC) is the result of an ongoing process of misplaced calcium in the inner and medial layers of the arteries, which has emerged as a critical contributor to cardiovascular events in CKD. Beyond its established role in blood clotting and bone health, vitamin K appears crucial in regulating VC via vitamin K-dependent proteins (VKDPs). Among these, the matrix Gla protein (MGP) serves as both a potent inhibitor of VC and a valuable biomarker (in its inactive form) for reflecting circulating vitamin K levels. CKD patients, especially in advanced stages, often present with vitamin K deficiency due to dietary restrictions, medications, and impaired intestinal absorption in the uremic environment. Epidemiological studies confirm a strong association between vitamin K levels, inactive MGP, and increased CVD risk across CKD stages. Based on the promising results of pre-clinical data, an increasing number of clinical trials have investigated the potential benefits of vitamin K supplementation to prevent, delay, or even reverse VC, but the results have remained inconsistent.

The available evidence on vitamin K status in cystic fibrosis (CF) is scarce, lacking data on vitamin K2 (menaquinones-MK). Therefore, we assessed vitamin K1, MK-4 and MK-7 concentrations (LC-MS/MS) in 63 pancreatic insufficient and modulator naïve CF patients, and compared to 61 healthy subjects (HS). Vitamin K1 levels did not differ between studied groups. MK-4 concentrations were higher (median <1st-3rd quartile>: 0.778 <0.589-1.086> vs. 0.349 <0.256-0.469>, p < 0.0001) and MK-7 levels lower (0.150 <0.094-0.259> vs. 0.231 <0.191-0.315>, p = 0.0007) in CF patients than in HS. MK-7 concentrations were higher in CF patients receiving K1 and MK-7 supplementation than in those receiving vitamin K1 alone or no supplementation. Moreover, vitamin K1 concentrations depended on the supplementation regime. Based on multivariate logistic regression analysis, we have found that MK-7 supplementation dose has been the only predictive factor for MK-7 levels. In conclusion, vitamin K1 levels in CF are low if not currently supplemented. MK-4 concentrations in CF patients supplemented with large doses of vitamin K1 are higher than in HS. MK-7 levels in CF subjects not receiving MK-7 supplementation, with no regard to vitamin K1 supplementation, are low. There do not seem to be any good clinical predictive factors for vitamin K status.

Newborns are prone to hemorrhagic disease due to vitamin K deficiency for multiple reasons, including vitamin K absence in breast milk and formula preparation, sterile gut with limited absorption, and lack of placental transfer. Despite the importance of vitamin K administration at birth in preventing hemorrhagic disease in infants, some parents still refuse administration to their newborns. One of the unexpected but preventable reasons is the language barrier related to special dialects, resulting in misunderstanding the benefits of vitamin K administration and complications related to vitamin K deficiency. We present a case of hemorrhagic disease of the newborn due to vitamin K deficiency following the parental refusal of postnatal prophylactic vitamin K due to a language barrier that resulted in miscommunication. Although appropriate education was provided to the family via Spanish interpreter as requested, it was later revealed that the family was speaking a special dialect, and they did not fully understand the importance of vitamin K prophylaxis. The patient experienced intracranial hemorrhage with full recovery after treatment and surgical intervention. Upon reviewing the case, the parents were speaking a rare dialect of Spanish, that was not known to the Spanish medical interpreters. A combination of a Spanish medical translator and a family friend was necessary for effective communication with the family.

BACKGROUND: Vitamin K deficiency can lead to severe coagulation dysfunction, which may be dangerous and fatal, especially in patients undergoing surgery.
METHODS: We report an 84-year-old male patient with gallstones and cholecystitis who had a severe coagulation disorder without bleeding symptoms after endoscopic papillary balloon dilation for removal of bile duct stones. After vitamin K supplementation, the coagulation dysfunction was corrected the next day.
RESULTS: In this case, long-term antibiotic treatment, inadequate diet, and abnormal liver function led to coagulation dysfunction. After vitamin K supplementation, the blood coagulation disorder was corrected and serious consequences were prevented. Significantly elevated coagulation function was considered to be caused by vitamin K deficiency.
CONCLUSIONS: This case indicates that coagulation dysfunction caused by vitamin K deficiency may occur within a few days. Laboratory personnel should fully understand the risks of vitamin K deficiency in elderly patients undergoing surgery with severely restricted diet, impaired absorption, and long-term use of cephalosporin anti-inflammatory therapy, and promptly remind clinical doctors.

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This case report presents a rare occurrence of coagulopathy induced by antibiotics in a woman in her 90s with chronic bowel obstruction and massive colon cancer. The patient developed vitamin K deficiency-related coagulopathy following antibiotic administration, resulting in bleeding complications. Despite initial consideration of disseminated intravascular coagulation, further investigations revealed antibiotic-induced vitamin K deficiency. Prompt discontinuation of antibiotics and IV vitamin K2 administration led to the resolution of coagulopathy. The case emphasizes the importance of cautious antibiotic use in patients with chronic bowel obstruction and prolonged fasting. The protein induced by vitamin K absence-II (PIVKA-II) proved valuable in diagnosing vitamin K deficiency. The learning points include the potential for coagulopathy with antibiotics in prolonged bowel obstruction and the utility of PIVKA-II in assessing vitamin K deficiency. Healthcare providers should exercise caution when administering antibiotics in similar clinical scenarios.

BACKGROUND: Extra-hepatic vitamin K-status, measured by dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP), maintains vascular health, with high levels reflecting poor vitamin K status. The occurrence of extra-hepatic vitamin K deficiency throughout the disease of COVID-19 and possible associations with pulmonary embolism (PE), and mortality in intensive care unit (ICU) patients has not been studied. The aim of this study was to investigated the association between dp-ucMGP, at endotracheal intubation (ETI) and both ICU and six months mortality. Furthermore, we studied the associations between serially measured dp-ucMGP and both PE and mortality.
METHODS: We included 112 ICU patients with confirmed COVID-19. Over the course of 4 weeks after ETI, dp-ucMGP was measured serially. All patients underwent computed tomography pulmonary angiography (CTPA) to rule out PE. Results were adjusted for patient characteristics, disease severity scores, inflammation, renal function, history of coumarin use, and coronary artery calcification (CAC) scores.
RESULTS: Per 100 pmol/L dp-ucMGP, at ETI, the odds ratio (OR) was 1.056 (95% CI: 0.977 to 1.141, p = 0.172) for ICU mortality and 1.059 (95% CI: 0.976 to 1.059, p = 0.170) for six months mortality. After adjustments for age, gender, and APACHE II score, the mean difference in plasma dp-ucMGP over time of ICU admission was 167 pmol/L (95% CI: 4 to 332, p = 0.047). After additional adjustments for c-reactive protein, creatinine, and history of coumarin use, the difference was 199 pmol/L (95% CI: 50 to 346, p = 0.010). After additional adjustment for CAC score the difference was 213 pmol/L (95% CI: 3 to 422, p = 0.051) higher in ICU non-survivors compared to the ICU survivors. The regression slope, indicating changes over time, did not differ. Moreover, dp-ucMGP was not associated with PE.
CONCLUSIONS: ICU mortality in COVID-19 patients was associated with higher dp-ucMGP levels over 4 weeks, independent of age, gender, and APACHE II score, and not explained by inflammation, renal function, history of coumarin use, and CAC score. No association with PE was observed. At ETI, higher levels of dp-ucMGP were associated with higher OR for both ICU and six month mortality in crude and adjusted modes, although not statistically significantly.

Vitamin K deficiency can cause coagulopathy; therefore, supplementation is recommended to prevent intracranial hemorrhage in newborns. Some reports have shown that maternal vitamin K deficiency is associated with intracranial hemorrhage in the fetus. However, no clear guidelines exist for the diagnosis and treatment of maternal vitamin K deficiency to prevent fetal intracranial hemorrhage. We report a case of intrauterine fetal death due to intracranial hemorrhage associated with maternal vitamin K deficiency resulting from hyperemesis gravidarum. In this case, maternal protein induced by vitamin K absence II (PIVKA-II) was high at the time of intrauterine fetal death. Therefore, measuring maternal PIVKA-II levels in high-risk cases may help determine the timing of therapeutic interventions for vitamin K deficiency during pregnancy.

Vitamin K (VK), a fat-soluble vitamin, is essential for the clotting of blood because of its role in the production of clotting factors in the liver. Moreover, researchers continue to explore the role of VK as an emerging novel bioactive molecule with the potential function of improving bone health. This review focuses on the effects of VK on bone health and related mechanisms, covering VK research history, homologous analogs, dietary sources, bioavailability, recommended intake, and deficiency. The information summarized here could contribute to the basic and clinical research on VK as a natural dietary additive and drug candidate for bone health. Future research is needed to extend the dietary VK database and explore the pharmacological safety of VK and factors affecting VK bioavailability to provide more support for the bone health benefits of VK through more clinical trials.

Nutritional support is essential for patients with severe motor and intellectual disabilities (SMID) to ensure the smooth provision of medical care. These patients often require long-term tube feeding with enteral formulas, potentially leading to deficiencies in vitamins and trace elements. Additionally, frequent antibiotic use for infections often disrupts gut microbiota, inhibiting vitamin K2 production by intestinal bacteria. We assessed the serum protein induced by vitamin K absence or antagonists-II (PIVKA-II) and undercarboxylated osteocalcin (ucOC) levels to assess the vitamin K status in 20 patients with SMID (median age: 44.1 years, 11 men and 9 women) undergoing long-term tube feeding for durations ranging from 3 to 31 years. Thirteen (65%) and nine (45%) patients had elevated PIVKA-II (<40 mAU/mL) and serum ucOC levels (reference value < 4.50 ng/mL), respectively. Dietary vitamin K1 intake did not differ between patients with and without elevated PIVKA-II levels. Vitamin K2 supplementation for 3 months decreased serum PIVKA-II levels near those within the reference range. Approximately half of the patients with SMID on tube feeding had subclinical vitamin K deficiency. Further studies are needed to ascertain if long-term vitamin K2 supplementation effectively prevents vitamin K deficiency-induced hypercoagulation, osteoporosis, and vascular calcification in patients with SMID.