Osteoporosis International
Volume 26, Issue 11, 2015, Pages 2607-2615

Biochemical and clinical deficiency is uncommon in African immigrants despite a high prevalence of low vitamin D: the Africans in America study (Article)

Thoreson C.K. , Chung S.T. , Ricks M. , Reynolds J.C. , Remaley A.T. , Periwal V. , Li Y. , Sumner A.E.*
  • a Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bld 10-CRC, Rm 6-5940, MSC 1612, 9000 Rockville Pike, Bethesda, MD 20892-1612, United States
  • b Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bld 10-CRC, Rm 6-5940, MSC 1612, 9000 Rockville Pike, Bethesda, MD 20892-1612, United States
  • c Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bld 10-CRC, Rm 6-5940, MSC 1612, 9000 Rockville Pike, Bethesda, MD 20892-1612, United States
  • d Nuclear Medicine Division, Radiology and Imaging Sciences Department, Clinical Center, NIH, Bethesda, MD 20892, United States
  • e Lipoprotein Metabolism Section, Cardiopulmonary Branch, National Heart Lung Blood Institute, NIH, Bethesda, MD 20892, United States
  • f Laboratory of Biological Modeling, Computational Medicine Section, NIDDK, NIH, Bethesda, MD 20892, United States
  • g Laboratory of Biological Modeling, Computational Medicine Section, NIDDK, NIH, Bethesda, MD 20892, United States
  • h Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bld 10-CRC, Rm 6-5940, MSC 1612, 9000 Rockville Pike, Bethesda, MD 20892-1612, United States

Abstract

Summary: African ancestry is associated with low vitamin D levels but high bone density. Fifty percent of African immigrants had low vitamin D levels, but <10 % had evidence of deficiency. The value of providing vitamin D supplementation to African immigrants without evidence of deficiency needs to be determined. Introduction: The Endocrine Society and Institute of Medicine (IOM) have concluded from studies in largely white populations that 25(OH)D is necessary for bone health. However, their definition of vitamin D insufficiency differs. The Endocrine Society recommends a 25(OH)D threshold of <30 ng/mL. The IOM uses a lower threshold of 25(OH)D of <20 ng/mL. As African ancestry is associated with decreased 25(OH)D but increased bone mineral density (BMD), the applicability of these thresholds to Africans is unknown. Therefore, we examined in African immigrants the relationship of 25(OH)D to parathyroid hormone (PTH) and BMD. Methods: One hundred eighty-six African immigrants(69 % male, age 38 ± 10 (mean ± SD), range 20–64 years) living in metropolitan Washington, DC, were enrolled. BMD was determined from whole-body dual-energy X-ray absorptiometry (DXA) scans. Decreased BMD required T-scores ≤−1.0. The threshold for low 25(OH)D was the concentration of 25(OH)D at which PTH became suppressed. This is known as the inflection point. Biochemical deficiency required low 25(OH)D and PTH of >65 pg/mL. Clinical deficiency required low 25(OH)D and T-scores ≤−1.0. Results: 25(OH)D <30 and <20 ng/mL occurred in 83 and 46 % of African immigrants, respectively. PTH inversely correlated with 25(OH)D (r = −0.31, P = 0.002). The inflection point occurred at a 25(OH)D concentration of 20 ng/mL. Biochemical and clinical deficiency occurred in only 8 and 3 % of immigrants, respectively. Conclusion: As PTH became suppressed at 25(OH)D of 20 ng/mL, the 25(OH)D <20 ng/mL threshold for insufficiency may apply to African immigrants. However, ~50 % of African immigrants have 25(OH)D <20 ng/mL, but only <10 % had evidence of deficiency. The value of providing vitamin D supplementation to the large number of African immigrants with 25(OH)D <20 ng/mL and no detectable evidence of deficiency needs to be determined. © 2015, International Osteoporosis Foundation and National Osteoporosis Foundation.

Author Keywords

Bone mineral density Vitamin D African immigrants Parathyroid hormone

Index Keywords

dual energy X ray absorptiometry photon absorptiometry immigrant Absorptiometry, Photon controlled clinical trial physiology PTH protein, human physical disease by body function vitamin blood level human epidemiology middle aged District of Columbia statistics and numerical data Vitamin D controlled study priority journal Seasons ethnology African American procedures analogs and derivatives season United States Young Adult cross-sectional study parathyroid hormone migrant Humans 25 hydroxyvitamin D male Emigrants and Immigrants female clinical evaluation diagnostic test accuracy study biochemical deficiency clinical deficiency prevalence seasonal variation vitamin D deficiency Article blood major clinical study adult Bone Density vitamin supplementation bioavailability 25-hydroxyvitamin D African Americans pathophysiology parathyroid hormone blood level
Link
https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944353670&doi=10.1007%2fs00198-015-3169-z&partnerID=40&md5=84b1460a748364230828a3c269c74e85
DOI: 10.1007/s00198-015-3169-z
ISSN: 0937941X
Cited by: 3
Original Language: English