Pri-Med Southwest: What Is the Best Approach to Treating Vitamin D Deficiency?

At Pri-Med Southwest, Frank Domino, MD, discussed the dangers of vitamin D deficiency and recommended screening and supplementation for at-risk patients.

There has been much attention given to the prevalence of vitamin D deficiency in the United States. Frank Domino, MD, Associate Professor and Clerkship Director of Family Medicine and Community Health at the University of Massachusetts Medical School, spoke Thursday at Pri-Med Southwest 2011 about the condition and offered practical information for its diagnosis and treatment. During his presentation, “Vitamin D Deficiency in an Ambulatory Setting,” Domino said that the cause of this widespread vitamin D deficiency is not known, but it has been suggested that decreased milk consumption, obesity, reduced sun exposure (due to lifestyle, UV-protected windows, and sunscreen use), and increased use of proton-pump inhibitors may all play a role. Vitamin D obtained through ultraviolet light, diet, or supplements is processed in the liver to calcidiol (25-hydroxy vitamin D). It is then converted to its active form, calcitriol (1,25-dihydroxy vitamin D), usually by the kidney. Calcitriol increases intestinal absorption of calcium, increases parathyroid hormone-mediated bone resorption, and decreases renal calcium and phosphate excretion.

Who is at risk for Vitamin D deficiency?

Domino recommended that primary care providers should immediately initiate routine screening for vitamin D deficiency among their patients who are most at risk, namely:

• Senior citizens
• Women who are pregnant or who are 50 years of age or older
• People who are dark-skinned, wear veils frequently, are home bound, live in a long-term care facility, have chronic aches, have multiple fractures, are prone to intestinal malabsorption, have coronary heart disease

Prevention, testing, and treatment

Routine daily supplementation of vitamin D is recommended for all patients according to their vitamin D level status (see table, below). The minimum daily doses of vitamin D recommended by the Institute of Medicine (IOM) are: 600 IU for adults who are between the ages of 19 and 70 years and 800 IU for adults who are 71 years of age or older. Aside from sun exposure, vitamin D supplements in the form of vitamin D2 or vitamin D3 are the best option for obtaining vitamin D, said Domino. Both forms have been shown to be equally effective in maintaining serum 25-hydroxyvitamin D levels. According to the IOM, the maximum amount daily amount of vitamin D that can be safely added to the diet is 4,000 IU.

Foods that offer substantial amounts of vitamin D include cod liver oil (1,360 IU per 1 tbsp. serving), cooked salmon (360 IU per 3.5 oz. serving), cooked mackerel (345 IU per 3.5 oz. serving), canned tuna fish (200 IU per 3 oz. serving), and canned sardines (250 IU per 1.75 oz. serving). Contraindications to vitamin D supplementation include: sarcoidosis, tuberculosis, lymphoma, and primary hyperparathyroidism.

The 25-hydroxy vitamin D level is the most reliable and sensitive measure of vitamin D.

Status

25-hydroxy Vitamin D Level

Treatment^*

Within normal limit

30-100 ng/ml

2,000 IU per day

insufficient

20-30 ng/ml

4,000 IU per day

Deficient

<20 ng/ml

50,000 IU vitamin D₂ per week for 12 weeks

Then 4,000 IU vitamin D₃ per day

* All patients should also receive daily Calcium (1,000 mg).

Outcomes that may be influenced by vitamin D

There is good evidence associating vitamin D deficiency with: depression among obese individuals, risk of fall and fracture, risk of myocardial infarction and all-cause mortality, osteoporosis, and hypertension among non-Hispanic blacks. There is also data indicating that vitamin D deficiency may be linked to premenstrual syndrome and cancer.

When studied in randomized clinical trials, vitamin D supplementation did not improve the following outcomes: chronic myalgia, fibromyalgia, seasonal affective disorder, obesity, and pain from osteoarthritis.

Take-home Message

• Screen at-risk patients
• Test 25-hydroxy vitamin D level
• Treat according to status
• Prescribe prevention for all patients: 2,000 - 4,000 IU per day, plus calcium