Whereas some vitamin deficiencies can lead to serious illnesses that can be life threatening down the line, Vitamin D can pose serious health problems. Studies have shown that people who have Vitamin D deficiency are more likely to develop heart disease and blockages in their coronary arteries. Vitamin D deficiency is also related to hypertension. Hypertension can lead to kidney failure. Similarly, among the aged, Vitamin B12 deficiency can lead to many life-threatening health complications. Therefore, it is very important to get a vitamin deficiency test done as early as possible.