Recently there has been a lot of news about Vitamin D, whether it is network news, a medical magazine or Reader’s Digest. They are all talking about Vitamin D and its deficiency. The importance of Vitamin D can be realized when it is linked with cardiovascular problems as well as blood pressure, bone disease and prevention of many cancers.

Vitamin D is found in many dietary sources such as fish, eggs, fortified milk, etc. The sun also contributes significantly to the daily production of Vitamin D and as little as 10 minutes of exposure to the arms, legs, face and hands is thought to be enough to prevent deficiencies. There are several forms of Vitamin D: Vitamin D2 is synthesized by plants and Vitamin D3 is synthesized by humans in the skin when exposed to sunlight. Sun screen and dark skin pigmentation also reduce skin synthesis of Vitamin D.

The major biologic function of Vitamin D is to maintain normal blood levels of calcium and phosphorous. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. Recently, research also suggests Vitamin D may provide protection from osteoporosis, hypertension, cancer and several autoimmune diseases. Patients with chronic kidney disease are especially susceptible due to the inability to convert Vitamin D to an active form, leading to Vitamin D deficiency.

According to Dr. Edward Giovannucci of Harvard University, a study of 18,225 men provides the strongest evidence to date for a link between Vitamin D deficiency and higher risk of heart attack. Vitamin D deficiency is associated with an increased risk of new onset coronary artery calcification, a finding that may help explain why cardiovascular events and death are more likely in this type of patient.

This association is stronger in a patient with impaired kidney function. Cardiovascular disease and death rise dramatically as kidney failure progresses.

The study led by Austrian researchers involved 3,258 men and women in southwest Germany. Participants were 62 years old on average, most with heart disease, whose Vitamin D levels were checked in weekly blood tests. During eight years of followup, 737 died, including 463 from heart related problems. According to some of the vitamin tests they used, there were 307 deaths in patients with the lowest levels versus 103 deaths in those with the highest levels. The researchers calculated that deaths from all causes were about twice as common among patients in the lowest level group.

In fact, Vitamin D has been shown to help regulate the body's disease fighting immune system and also linked to high blood pressure, diabetes and obesity, all of which can contribute to heart problems. Low Vitamin D levels also have been linked with several kinds of cancer and some researchers believe Vitamin D could even be used to help prevent malignancies.

It is estimated that at least 50 percent of older adults worldwide have low Vitamin D levels and it is thought to probably effect substantial numbers of younger people as well. Possible reasons may be decreased outdoor activities, air pollution and as people age, a decline in the skin's ability to produce Vitamin D from ultraviolet rays.

The daily requirement of this vitamin in adults is 400 to 600 International Units. For chronic kidney disease patients much higher doses of up to 50,000 IU (Drisdol) is prescribed either weekly or monthly depending on the level of vitamin. Hemodialysis patients are requiring it monthly to prevent deficiency as long as they are on dialysis.

In conclusion, in light of the recent discoveries, the role of Vitamin D is taking on much more significance. As nephrologists, we are required to check Vitamin D levels on every patient with abnormal kidney function and correct the deficiency if found.

This Week's Circulars