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Studio osservazionale cross-sectional volto a valutare lo status della vitamina K e del suo potenziale ruolo nell'ambito delle fratture vertebrali e delle calcificazioni vascolari nel dializzato (Studio Kappa)
Full text linkBackground
Vitamin K, vitamin K1 or Phylloquinone (PK) and vitamin K2 or Menaquinone (MK), is involved not only in the production of coagulation proteins, but also in the production of bone and matrix Gla proteins regulating bone and vascular calcification. Studies suggest that low vitamin K concentrations are associated with increase in the risk of fractures and vascular calcification. Hemodialysis (HD) patients are at high risk of these complications. We carried out a cross-sectional study to establish the prevalence of vitamin K deficiency and to assess the relationship between vitamin K status, vertebral fractures (VF) and vascular calcification (VC) in HD patients.
Materials and Methods
Multicenter, cross-sectional study in 387 HD patients, 18 hospital based dialysis centers in Northern and Middle Italy. We assessed plasma levels Vitamin K (in High-performance liquid chromatography, HPLC), Osteocalcin o Bone GLA Protein (BGP), Matrix GLA Protein (MGP) and other routine biomarkers. We had a Healthy Control Group ( comparable for age and sex).
VF and VC assessment was centralized and double blind. We evaluated VF with a computerized analysis, of scanned L-L vertebral X-rays (D4 to L5). A reduction of > 20% of vertebral body height was considered VF. The severity of the vertebral fractures was estimated as Mild, Moderate or Severe (reduction: 20–25%, 25–40% or >40%, respectively).
We evaluated VC with Witteman’s method (Lancet, 1994). VC was quantified by measuring the length of calcific deposits along the wall of the Abdominal Aorta (Mild 0.1-5 cm, Moderate 5.1-10 cm and Severe 10 cm). We also evaluated the presence or absence of calcifications of the Iliac Arteries in the same radiograph.
Any differences were resolved by consensus.
Results
Important proportions of patients had deficiency of vitamin K.
We found High prevalence VF and VC.
Conclusions
This multicenter study, based on a significant dialysis population in the North and Middle Italy shows a relevant Vitamin K deficiency related to clinical important complications such as VF and VC. We believe that in dialysis patients an adequate intake of vitamin K should be recommended together to the Calcium and Vitamin D Intake in CKD patients to promote correct Bone calcification and avoiding in this way to cause harmful VC.
Additional studies should be performed to investigate the role of vitamin K in bone fractures and in vascular calcification in the general populationPremessa
La vitamina Kappa (K), intesa K1 o Fillochinone (PK) e K2 o Menachinone (MK), è coinvolta nella produzione non solo delle proteine della coagulazione ma anche nella produzione di proteine GLA dell’osso e della matrice che regolano la mineralizzazione ossea e le Calcificazioni Vascolari (CV). Studi in letteratura suggeriscono che basse concentrazioni di Vitamina K sono associate con aumentato rischio di fratture e calcificazioni vascolari. I pazienti (pz) in emodialisi (HD) sono ad alto rischio di tali complicanze. Noi abbiamo condotto uno studio osservazionale volto a valutare la Prevalenza del Deficit di Vitamina K e la associazione tra lo Status della Vitamina K, le Fratture Vertebrali (FV) e le CV nei pz in HD.
Materiali e Metodi
Studio Osservazionale Multicentrico in 387 pz in HD, 18 centri dialisi tra il nord e centro Italia. Abbiamo misurato i livelli di: vitamina K (in High-performance liquid chromatography, HPLC), Osteocalcina o Bone GLA Protein (BGP), Matrix GLA Protein (MGP) e altri biomarkers di routine. Un gruppo di soggetti sani (comparabile per età e sesso) è stato usato come controllo.
La valutazione delle FV e delle CV era centralizzata e a doppio cieco. Le FV erano valutate mediante analisi computerizzata scannerizzando la Radiografia della Colonna vertebrale in L-L (T5-L4). Era considerata FV una riduzione dell’altezza del corpo vertebrale >20%. La severità della FV era stimata in Lieve, Moderata e Severa (rispettivamente riduzione del: 20-25%, 25-40% e > 40%).
Valutammo le CV con il metodo di Witteman (Lancet,1994). La CV era misurata dalla lunghezza del deposito calcifico lungo la parete dell’Aorta Addominale (Lieve 0.1-5cm, oderato 5.1- 10cm e severa > 10cm). Valutammo anche la presenza o assenza della calcificazione delle Arterie Iliache nella medesima Radiografia.
Ogni differenza era risolta dal consensus.
Risultati
I pazienti in dialisi cronica presentavano importanti deficit di Vitamina K.
Abbiamo inoltre trovato alta prevalenza di FV e CV.
Conclusioni
Questo studio, basato su una importante casistica di pazienti in dialisi del Nord e Centro Italia dimostra che un’importante frazione di tali pazienti è carente di vitamina k e che tale stato carenziale è correlato a complicanze di estremo interesse clinico, quali le FV e le CV. Su tale base si ritiene che ai pazienti con malattia renale cronica, assieme all’intake di Calcio e Vitamina D, si dovrebbe raccomandare l’assunzione di un adeguato introito di vitamina K al fine di realizzare una corretta Calcificazione dell’osso ed evitando in questo modo di causare il danno della CV.
Studi aggiuntivi dovrebbero essere effettuati per investigarae il Ruolo della Vitamina K nelle Fratture Ossee e nelle CV anche nella popolazione general
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use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
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