Vitamin D in Rheumatology: Cause and Effect Unclear

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September 15, 2015 • By

The controversy over vitamin D is hearty enough to confuse even seasoned rheumatologists, says Nathan Wei, MD, The Arthritis Treatment Center, Frederick, Md.

Vitamin D appears to be in the same conundrum right now in rheumatology. Although there’s the general thought that optimal levels can be beneficial for patients, it’s not always clear how much is needed, how much vitamin D contributes to disease development, and whether D has any protective factor against rheumatic disease.

What’s certain is testing -keep reading- for vitamin D levels is popular right now, says Stuart D. Kaplan, MD, chief of rheumatology atSouth Nassau Communities Hospital in Oceanside, N.Y. When he started to practice rheumatology in 1989, he says checking vitamin D levels was not even on the radar screen.

As the specialty’s knowledge of rheumatic disease has increased, there’s a general thought that vitamin D may help combat osteoporosis and reduce the risk for falls, says Linda A. Russell, MD, assistant attending physician, Hospital for Special Surgery, New York.

The current enthusiasm for Vitamin D stems, in part, from the public’s interest in finding more “natural” ways to prevent and treat disease that do not involve conventional medications, says Sharon L. Kolasinski, MD, Division of Rheumatology, University of Pennsylvania, Philadelphia.

What We Know about Vitamin D

There’s a multitude of ongoing research related to vitamin D right now, and while some questions remain unanswered, what’s clear is that a deficiency is a risk factor for many diseases, including heart disease and cancer, says Amber Toyer, community outreach manager at the nonprofit Vitamin D Council in San Luis Obispo, Calif. “Researchers are discovering that vitamin D deficiency can make some diseases more severe. Researchers are also discovering that vitamin D can be an important piece in the treatment of some illnesses and diseases,” she says. There’s a substantial amount of evidence that shows the importance of vitamin D in preventing breast, colorectal and prostate cancer, and there’s also a good deal of research showing a relationship between vitamin D and multiple sclerosis, Ms. Toyer adds.

Within rheumatology, it’s clear from the research that vitamin D plays a role in bone health and the possible development of osteoporosis and other bone conditions, Ms. Toyer says.

“The important role of vitamin D in osteoporosis is indisputable,” says Petros Efthimiou, MD, FACR, associate chief of rheumatology, New York Methodist Hospital, and associate professor of clinical medicine and rheumatology, Weill Medical College of Cornell University, New York. “However, when it comes to autoimmune diseases, low vitamin D levels have been implicated in some, but not all diseases. Several recent studies have produced conflicting results.”

“With the discovery that vitamin D receptors are present on all nucleated cells, including cells of the immune system, there has been speculation that vitamin D could modulate immune function and potentially influence the risk of or the course of autoimmune disease,” Dr. Kolasinski says. Still, the evidence is not yet definitive, she says.

In the Clinic

So how does the research translate into clinical daily life? First, many rheumatologists actively check vitamin D levels in their patients at least once a year, if not more often.

“I frequently test for vitamin D levels in patients at risk of or who have osteopenia/osteoporosis, including peri- and postmenopausal women,” says Orrin Troum, MD, rheumatologist, Providence Saint John’s Health Center, Santa Monica, Calif. “Other ‘at-risk’ patients are those who don’t have adequate sun exposure or use sunscreen on all sun-exposed areas.”

“I test vitamin D levels at least annually and recommend supplementation to all those who are found to be deficient, as well as those on steroids [because] I know they will be at increased risk for osteoporosis,” Dr. Kolasinski says.

It’s especially common to find low vitamin D levels in the colder parts of the country, such as the Northeast, Dr. Kaplan says. However, those levels will likely rise in the summer.

Dr. Wei tests patients at three different sun-exposure times of the year—the fall, the early spring and in the dead of winter.

Then, rheumatologists must determine what they consider to be a low vitamin D level. Many believe a level of at least 30 or 32 nanograms is acceptable to sufficiently suppress the parathyroid hormone, Dr. Russell says.

A level of 30 or less is when Dr. Efthimiou will recommend supplementation.

The Vitamin D Council recommends a sufficient level as 40 to 80 nanograms—and it recommends most people should strive for a level of 50, which is what Dr. Wei aims for in patients as well. The Endocrine Society says 30 or more is sufficient. Althoughvitamin D toxicity is not seen often, it’s generally considered to occur at 150 nanograms or higher.

Then there’s the decision of how much supplementation to recommend. If a patient has a level of 20 or lower, Dr. Kaplan advises a dose of 2,000 international units (IU) daily. If a patient’s level is below 10, he’ll start with a pharmaceutical dose of 50,000 units once a week and sometimes even twice a week. He will check levels at four to eight weeks to see if there is any improvement.

Dr. Russell believes that recommendations from the National Osteoporosis Foundation are reasonable; it recommends a dose of 400 to 800 IU for patients under age 50 and 800 to 1,000 IU daily for those aged 50 or older. If a patient is taking 1,000 IU daily and is still low, she’ll recommend taking more—although she notes that patients may feel overwhelmed by the variety of choices they see at the drugstore, with doses ranging from 400 IU to 10,000 IU. She advocates asking patients to report all over-the-counter supplements they take and the dosage to ensure there are no out-of-the-norm dosing issues.

For patients with levels between 20 and 30, Dr. Efthimiou advises a dose of 2,000 to 4,000 IU daily, along with an appropriate diet. Although supplementation is the most often recommended route to boost vitamin D, eating certain foods, such as fish, milk and eggs, can also improve vitamin D levels.

And what about sun exposure? It may not be music to a dermatologist’s ears, but some clinicians also recommend brief sun exposure to boost absorption. Dr. Troum recommends 10 minutes of sun exposure daily without sunscreen, if it’s not contraindicated, because it can be in patients who have had skin cancer. Still, the idea of sun exposure for vitamin D is always a push/pull, with the dermatologists treating patients as well, Dr. Wei says.

Another population that may want to stick with supplements is lupus patients, because they tend to be photosensitive, Dr. Kaplan says. Their vitamin D levels tend to be low, but it’s not clear if that’s because they often avoid the sun and, thus, have low levels or because lack of the vitamin exacerbates lupus, he says.

Vitamin D has many benefits, but Dr. Kolasinski says it’s important not to overestimate the benefits of any single vitamin or supplement.

What Needs Further Research

There are still many questions that rheumatologists would like answered about vitamin D.

One major question is whether increasing vitamin D in patients with insufficient levels, either with diet or supplements, can improve outcomes in patients with autoimmune disease, such as RA or lupus, Dr. Troum says. Randomized controlled trials with supplementation would be helpful to answer this question.

At the same time, such studies would be difficult because there are so many confounding variables that can affect disease, Dr. Kaplan says.

It would also be valuable to see research that correlates vitamin D levels with an increase or decrease in falls within the rheumatology population, Dr. Russell says.

There are some vitamin analogues under research that may exert the immunomodulatory effects of vitamin D while dissociating it from its effects on calcium metabolism, Dr. Efthimiou says.

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