Fracture After Fall in a Middle-Aged African American Woman

A 58-year-old African American woman comes for a follow-up visit after sustaining a fracture of the right radius, which occurred when she tripped on loose carpeting and broke her fall with an outstretched hand.

HISTORY

The patient is postmenopausal and was in good health before this incident. She takes a daily multivitamin supplement that contains 400 IU of vitamin D₂ and 200 mg of calcium. She eats no fish but drinks 1 small glass of milk daily. She has had no other fractures and has no known personal or family history of osteoporosis. She reports minimal physical activity and sunlight exposure. She has had no dual-energy x-ray absorptiometry (DEXA) scans.

PHYSICAL EXAMINATION

The patient's vital signs are normal; body mass index (BMI) is 30. Her right forearm is immobilized in a plaster case. She has no scoliosis.

LABORATORY AND IMAGING RESULTS

Results of a chemistry panel are normal; serum 25-hydroxyvitamin D level is 10 ng/mL. The alkaline phosphatase level is 172 U/L, and the calcium level is 9.1 mg/dL; γ-glutamyl transpeptidase level is 19 U/L. DEXA scanning reveals a T-score of –2 at L1 and a T-score of –1 at the hip.

Which of the following is true?

Answer and discussion on next page

CORRECT ANSWER: A

This patient has osteopenia that most likely is associated with vitamin D deficiency. Estimates of the prevalence of vitamin D deficiency among communitydwelling elderly men and women in the United States and Europe range from 40% to 100%.^1,2 Vitamin D is essential to bone health because it plays a critical role in calcium regulation; deficiency contributes to the development and progression of osteoporosis.

Most of the morbidity and mortality associated with osteoporosis results from fractures, particularly fractures of the spine and hip. Between 10% and 20% of persons who sustain a hip fracture die within 1 year, and 50% have permanent functional disability.³ Vitamin D deficiency in adults also causes muscle weakness, which contributes to the risk of falls and increases the rate of fracture.²

In addition, vitamin D has been associated with several other aspects of health maintenance. Higher levels reduce the risk of several cancers, including breast cancer, prostate cancer, non-Hodgkin lymphoma, and colorectal cancer.² Moreover, vitamin D deficiency has been associated with increased mortality from these cancers. Thus, choice A is correct.¹ Maintaining an adequate level of vitamin D has also been found to diminish the risk of multiple sclerosis and type 1 and type 2 diabetes mellitus and to normalize blood pressure in patients with hypertension.²

Causes of vitamin D deficiency. Sun exposure is the primary source of vitamin D for most persons. Energy absorbed from UV-B radiation converts previtamin D₃ into vitamin D₃ in the skin.⁴ Skin synthesis of vitamin D is limited by sunscreen use; darker skin; aging; and decreases in UV-B radiation associated with certain seasons, latitudes, and times of the day.^2,4 Thus, a lack of moderate sun exposure is the major cause of vitamin D deficiency.

Vitamin D can be obtained from some dietary sources. Oily fish are a natural source; and in the United States, some foods are fortified with vitamin D, including milk and some juices, bread, yogurt, and cheese. However, it is unusual for a person's diet to supply enough vitamin D to maintain adequate body stores. Thus, choice D is incorrect.¹

Diagnosis and screening. Vitamin D status is determined by measuring the serum level of 25-hydroxyvitamin D. Deficiency is defined as a serum 25-hydroxyvitamin D level of less than 20 ng/mL. More recent research has given rise to the concept of "vitamin D insufficiency." Insufficiency is a less well-defined parameter; however, a 25-hydroxyvitamin D level of more than 30 ng/mL is generally considered necessary to obtain the maximum clinical benefits.¹ Thus, choice B is incorrect. Note that a recommendation for routine screening for vitamin D status in healthy adults is not currently included in any universally accepted guidelines.

Treatment. Options for treating laboratory-confirmed vitamin D deficiency include the following regimens:

Vitamin D₃ supplementation is more effective than vitamin D₂ supplementation in maintaining serum levels of 25-hydroxyvitamin D; thus, higher doses of vitamin D₂ are required to achieve the same level.¹ However, in the United States, vitamin D₂ is the form of the vitamin that is usually prescribed.¹

The dosage required to maintain adequate levels of vitamin D after stores of 25-hydroxyvitamin D have been repleted is a subject of controversy. The Institute of Medicine's 1997 guidelines recommended 200 IU of vitamin D daily for children and adults aged 50 years or younger, 400 IU/d for persons aged 51 to 70 years, and 600 IU/d for persons aged 72 years and older.¹ However, many experts have suggested that these dosages are not adequate to obtain the maximum health benefits of this vitamin. It has been proposed that all persons who do not receive adequate sun exposure (defined by various formulas that take into account skin pigmentation, amount of skin exposed, time of day, time of year, and latitude) should receive 800 to 1000 IU of vitamin D daily.^1,4 Thus, this patient's multivitamin, which provides only 400 IU, does not contain this optimal quantity, making choice E incorrect.

Prognosis. The efficacy of vitamin D supplementation has been the subject of several recent studies. Vitamin D has been shown to reduce the incidence of hip fractures, nonvertebral fractures, and vertebral fractures.^3,5,6 One meta-analysis found that vitamin D at a dosage of 700 to 800 IU/d reduced the relative risk of hip fracture by 26% and the relative risk of nonvertebral fracture by 23% compared with calcium or placebo.³ The same meta-analysis showed that a daily dose of 400 IU did not prevent either type of fracture.³ However, a second meta-analysis found that 400 IU of vitamin D per day resulted in a 37% reduction in the risk of vertebral fractures.⁵

THE TAKE-HOME MESSAGE:

Treat vitamin D deficiency, defined as a 25-hydroxy-
vitamin D level of less than 20 ng/mL, with a high-dose regimen of vitamin D

₂

or D

₃

until the level is above 30 ng/mL; follow with a maintenance dosage.

Because 90% of all hip fractures in the elderly are the result of falls, studies have also investigated the ability of vitamin D to reduce fall risk.⁶ Several meta-analyses have found that supplementation with vitamin D resulted in reductions in fall risk of 22% to 35%.^2,3 A larger reduction was seen when a dosage of 800 IU/d was used. Thus, choice C is incorrect: supplementation with at least 800 IU of vitamin D per day should reduce this patient's risk of future falls and fractures.

Outcome of this case. The patient was given 50,000 IU of vitamin D₂ weekly for 8 weeks. A follow-up 25-hydroxyvitamin D level obtained at the end of 8 weeks was 36 ng/mL. A maintenance regimen of twice-daily oral supplementation with a combination of 500 mg of calcium citrate and 400 IU of vitamin D₂ was started. Weekly bisphosphonate therapy was initiated as well. The patient has had no subsequent fractures.

References:

REFERENCES:

1.

Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences.

Am J Clin Nutr.

2008;87:1080S-1086S.

2.

Holick MF. Vitamin D deficiency.

N Engl J Med.

2007;357:266-281.

3.

Bischoff-Ferrari HA, Willett WC, Wong JB, et al. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials.

JAMA.

2005;293:2257-2264.

4.

Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease.

Am J Clin Nutr.

2004; 80(suppl):1678S-1688S.

5.

Papadimitropoulos E, Wells G, Shea B, et al; Osteoporosis Methodology Group and The Osteoporosis Research Advisory Group. Meta-analyses of therapies for postmenopausal osteoporosis, part 8: meta-analysis of the efficacy of vitamin D treatment in preventing osteoporosis in postmenopausal women.

Endocr Rev.

2002;23:560-569.

6.

Jackson C, Gaugris S, Sen SS, Hosking D. The effect of cholecalciferol (vitamin D

₃

) on the risk of fall and fracture: a meta-analysis.

QJM.

2007;100: 185-192.

FOR MORE INFORMATION:

• Shoback D. Update in osteoporosis and metabolic bone disorders.

J Clin Endocrinol Metab.

2007;92:747-753.