Indications:
There are a number of structurally similar, naturally occurring compounds which have vitamin K activity. The major plant form is phylloquinone (vitamin K1). The menaquinones (vitamins K2, also referred to as MK) are predominately of bacterial origin.
In the typical Western diet, K1 and MK account for 90% and 10% of the vitamin K intake, respectively.
The liver synthesises seven vitamin K-dependent proteins that have a crucial role in blood coagulation (factors II, VII, IX and X, proteins C, S, and Z). Other vitamin K-dependent proteins (Gla proteins), with a widespread tissue distribution, have also been identified; this has led to a re-evaluation of the general physiological function of vitamin K and its role in human health.
Putative roles of Gla proteins now extend to a diversity of functions, such as the regulation of bone turnover and calcification, inhibition of vascular calcification, and roles in vascular repair processes.
There is an accumulating body of evidence that has linked sub-optimal vitamin K reserves in bone to an increased risk of osteoporotic fracture or to reduced bone mineral density.
Vitamin K1 is found chiefly in green leafy vegetables, while vitamin K2 is present in animal tissues. Like other fat-soluble vitamins, vitamin K is absorbed from the duodenum, where it is dependent on bile and pancreatic secretions for solubilisation. Any condition causing the intestinal malabsorption of fat will therefore lead to a secondary deficiency of fat-soluble vitamins, including vitamin K.
Patient Instructions:
Patients should ideally fast for 12 hours before taking blood for the assessment of vitamin K status and should have refrained from taking nutritional supplements for 24 hours prior to venepuncture.
Sample Requirements:
Yellow top (SST) blood collection tube. Sample must be centrifuged immediately and protected from light (light-proof mailing container provided with VHL test kit). Store serum chilled or frozen if any delay before submitting.
Postal Samples: Accepted (return by next-day post)