ORLANDO, Florida—Vitamin D got considerable attention at the American Association of Clinical Endocrinologists “sunshine state” 2008 annual meeting. Presentations included one documenting hypocalcemia due to vitamin D deficiency in a patient adhering to a vegan diet, a second showing widespread underdiagnosis of vitamin D deficiency in patients with osteoporosis, and a third reporting high rates of continuing vitamin D deficiency in patients who have had a previous hip fracture.

Bad news for vegans: hypocalcemia and vitamin D deficiency from a “healthy” diet

Kateryna Komarovskiy, MD, and Nathaniel Winer, MD, described hypocalcemia due to vitamin D deficiency in a patient who had followed a strict vegan diet.¹ The authors are at St. Vincent's Catholic Medical Center, Staten Island, NY.

The patient, who was from Grenada, was a 44-year-old male without significant past medical history. He presented with generalized weakness and bone pain for 2 to 3 months. He was practicing Rastafarian culture, including strict vegan diet, which included only unprocessed food of nonanimal origin. He was working night shifts.

Laboratory tests showed significant abnormalities for calcium, corrected by albumin of 6.6 mg/dL, phosphorus 2.8 mg/dL, intact PTH (parathyroid hormone) 214 pg/mL, creatinine 0.4 mg/dL, magnesium 2 mg/dL, vitamin D 25 level <4 (20-100) ng/mL, vitamin D1-25 8 (19-67) pg/mL. There was no evidence of malabsorption.

Because of the bone pain, plain film radiography was done and showed poorly healed old fractures of multiple ribs, and pelvic bones with evidence of severe osteopenia. The patient was diagnosed with secondary hyperparathyroidism and hypocalcemia due to vitamin D deficiency. The investigators believe this resulted from a combination of his diet, minimal exposure to sunlight, and race (hyperpigmented skin). “After dietary counseling, calcium and vitamin D supplementation, his calcium level normalized, and his generalized weakness and bone pain improved,” Dr. Komarovskiy said.

Dr. Komarovskiy explained that vegetarians consume food rich in oxalic (chives, parsley, spinach) and phytic acids (flaxseed, whole grains, nuts). These compounds interfere with calcium absorption from vegetable sources. Furthermore, the typical vegetarian diet contains less protein and may reduce calcium excretion.

“Our patient presented with hypocalcemia secondary to vitamin D deficiency and decreased calcium consumption. As a 44-year-old adult, he should have been consuming about 1000 mg/day of dietary calcium and 200 IU of vitamin D. By following the vegan diet, our patient believed that his healthy eating habits would protect him from obesity, diabetes, and dyslipidemia, which are common to the typical Western die,” Dr. Komarovskiy said.

Because ~2.5% of adults in the United States follow vegan diet, the study has important public health implications. A well-balanced vegan diet can provide an adequate source of the necessary vitamins and minerals, but this patient's did not.

“Clinicians should emphasize the importance of a well-balanced diet to their vegan patients, educate them about diet supplementation and vegetable-based sources of calcium and vitamin D, and provide early screening for osteoporosis,” Dr. Komaroskiy said.

Even osteoporosis patients taking calcium and vitamin D need routine vitamin D testing

Harinder Singh, MD, and colleagues reported retrospective data showing that >30% of osteoporosis patients who were regularly taking recommended levels of vitamin D and calcium supplements had low vitamin D levels.² “Our observations suggest that vitamin D deficiency in patients diagnosed with osteoporosis by DEXA scanning is underdiagnosed. We suggest vitamin D levels as part of initial evaluation of patients with osteoporosis,” Dr. Singh said.

The chart review study was conducted at the outpatient endocrinology clinic in Las Vegas, which included osteoporosis patients diagnosed on DEXA scan who had documented vitamin D levels, irrespective of race, gender, age, or other underlying diagnoses. The researchers analyzed data for 71 patients, all of whom were on vitamin D 800 IU and calcium 1200 mg/day. Laboratory data showed that 18.3% of subjects were vitamin D deficient (<20ng/mL) and 22.5% (16) were vitamin D insufficient (20-30 ng/mL). Furthermore, 9.86% of patients were hypocalcemic (<9 mg/dL).

“Our study demonstrates that many patients with osteoporosis who were on vitamin D and calcium had low vitamin D levels, which in turn contributes to increased risk of fractures. Therefore, all patients with osteoporosis should have vitamin D levels measured, and replaced adequately,” Dr. Singh said.

Vitamin D also overlooked after hip fracture

Even after a hip fracture, vitamin D deficiency is often overlooked, according to Akta Patel Mukherjee, MD, and Suzanne Rieke, MD. Their retrospective analysis of 117 patients who presented with acute hip fracture from November 2004 to January 2006 to Lahey Clinic in Burlington, Massachusetts, showed that 90.6% presenting were vitamin D insufficient, including 48% of patients who had been previously diagnosed with osteopenia or osteoporosis and 68% of those who had suffered previous fractures.

“The majority of patients presenting to our hospital with hip fracture, even with history of a previous fracture, were vitamin D deficient,” Dr. Mukerjee said. The investigators noted that history of fracture is not routinely identified as an osteoporosis risk equivalent that should be is aggressively treated with vitamin D.

References

1. Komarovskiy K and Winer N. Unhealthy outcome from a “healthy” diet. Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 706.
2. Singh H, Karmegan S, Manandhi A, et al. Vitamin D deficiency in patients with osteoporosis. Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 520.
3. Mukherjee AP, Rieke S, Prevalence of vitamin D deficiency among acute hip fracture patients in a New England hospital. Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 500.