Abstract
Introduction:
Vitamin D deficiency is common in dialysis patients, whereas vitamin K status is less investigated despite its important implications for bone metabolism (bone Gla protein is vitamin K-dependent) and for vascular calcifications (matrix Gla protein is vitamin K-dependent).
Materials and methods:
The aim of the study was to assess the prevalence of vitamin D and K deficiency and the presence of vertebral fractures and vascular calcifications in haemodialysis patients (compared with a healthy control group). Subjects: 68 patients, 49 males and 19 females, mean age 66.62 years (± SD 11.3), undergoing thrice-weekly haemodialysis; mean dialytic age: 68.14±56.14 months.
The presence of vertebral fractures was assessed by means of vertebral morphometry (D5–L4) using a quantitative, computerised method (MorphoXpress).
The presence of vascular calcifications was assessed by means of vertebral spinal X-ray in L-L.
We measured biohumoural bone-vascular mineral metabolism parameters: total BGP and decarboxylated BGP (ucBGP), total MGP and decarboxylated MGP (ucMGP).
The presence of vertebral fractures was taken to correspond to a >20% reduction in the height of the vertebral body; a reduction of between 15 and 20% was considered borderline (B).
Results:
In the patients, versus controls, there emerged: deficit of 25(OH)D (98%, 60% carenti-38% insufficienti); vitamin K1 deficiency 32.08%; increased total BGP and ucBGP, increase in total MGP and reduction of ucMGP.
The prevalence of vertebral fractures was 57.35%+B: 27.94%. Vertebral fractures were associated with: anagraphical age (p=0.028), P (p=0.0445) and total BGP (p=0.0420).
The prevalence of vascular calcifications was 84%. Vascular calcifications were associated with: anagraphical age (p=0.0205), Ca (p=0.0192) and ucMGP (0.0453).
Conclusions:
Marked vitamin D and K deficiency was associated with a high prevalence of vertebral fractures and vascular calcifications in haemodialysis patients with biohumoural bone mineral metabolism parameters within the KDOQI targets. Vitamin K is an important new biomarker of the bone-vascular axis in patients with chronic renal insufficiency.