Vitamin K is very important for coagulation, but it is also important for proper utilization of calcium. So don't just take calium supplements, but also take vitamin D(1,000-2,000 units), and perhaps 100 mcg a day of vitamin K if you don't eat foods high in vitamin k.

http://whfoods.org/genpage.php?tname=nutrient&dbid=112

Vitamin K2 is much more versatile and effective at a wide range of things. I would reccomend getting vitamin K from green veggies and taking a supplement like Jarrows MK-7 which is K2 extracted from Natto (fermented soy).