Elsevier

Mayo Clinic Proceedings

Volume 88, Issue 2, February 2013, Pages 176-183
Mayo Clinic Proceedings

Original article
Increasing Incidence of Nutritional Rickets: A Population-Based Study in Olmsted County, Minnesota

https://doi.org/10.1016/j.mayocp.2012.10.018Get rights and content

Abstract

Objective

To determine temporal trends in incidence and risk factors of nutritional rickets in a community-based population.

Patients and Methods

Rochester Epidemiology Project data were used to identify all children (aged <18 years) residing in Olmsted County, Minnesota, between January 1, 1970, and December 31, 2009, with diagnostic codes corresponding to rickets, vitamin D deficiency, hypovitaminosis D, rachitis, osteomalacia, genu varum, genu valgum, craniotabes, hypocalcemia, hypocalcemic seizure, and tetany. Record abstraction was performed to select individuals with radiographic confirmation of rickets. Age- and sex-matched controls were identified for the evaluation of risk factors. The main outcome measure was radiographic evidence of rickets without identifiable inherited, genetic, or nonnutritional causes. Incidence rates were calculated using Rochester Epidemiology Project census data.

Results

Of 768 children with eligible diagnostic codes, 23 had radiographic evidence of rickets; of these, 17 children had nutritional rickets. All 17 children were younger than 3 years, and 13 (76%) were of nonwhite race/ethnicity. Clinical presentation included poor growth (n=12), leg deformity (n=8), motor delay (n=5), leg pain (n=3), weakness (n=3), and hypocalcemia or tetany (n=2). The incidence of nutritional rickets in children younger than 3 years was 0, 2.2, 3.7, and 24.1 per 100,000 for the decades beginning in 1970, 1980, 1990, and 2000, respectively (P=.003 for incidence trend). Nutritional rickets was associated with black race, breast-feeding, low birth weight, and stunted growth (P<.05 for all). Four of 13 patients (31%) who underwent 25-hydroxyvitamin D testing had values less than 10 ng/mL.

Conclusion

Nutritional rickets remains rare, but its incidence has dramatically increased since 2000. Not all cases of rickets can be attributed to vitamin D deficiency.

Section snippets

Olmsted County and the Rochester Epidemiology Project

Olmsted County is located in the upper midwestern United States (centered at 44° North latitude). The population of Olmsted County increased from 82,955 in 1970 to 145,225 in 2009. Despite the 75% increase in total population, the number of children younger than 3 years, who are at greatest risk of rickets, had a much smaller increase—from 5133 in 1970 to 6277 in 2009 (a 22% increase). Racial diversity has been increasing. In the 2000 and 2010 censuses, the proportions of Olmsted County

Results

In total, 768 medical records were identified using the eligible diagnostic codes; diagnoses included leg deformities (n=517), hypocalcemia or tetany (n=131), vitamin D deficiency (n=60), osteomalacia (n=23), rickets (n=27), and craniotabes (n=10). Of the 369 patients who underwent radiography, 23 (6%) had confirmed rickets, and 17 of these (74%) were judged to have nutritional rickets. Of the 6 excluded cases of confirmed rickets, 3 had hypophosphatemic rickets and 1 each had rickets of

Discussion

As a population-based incidence study over 40 years, this report provides better information regarding the incidence and temporal trends of diagnosed nutritional rickets than previous studies. Unlike other case series, this study had the advantage of a defined population (ie, denominator), and, consequently, we could determine the actual incidence trend of nutritional rickets without the risk of referral bias. By requiring radiographic evidence of rickets, we avoided disease misclassification

Conclusion

We provide population-based evidence that the incidence of rickets has dramatically increased since 2000. Because all cases of nutritional rickets in this study were identified in children younger than 3 years, strategies for rickets prevention should focus on infants and toddlers. These strategies include vitamin D supplementation of breast-fed infants and ensuring adequate maternal vitamin D status during pregnancy, particularly in black children and in children who have recently entered the

Acknowledgment

The content of this article is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

References (36)

  • C.M. Gordon et al.

    Prevalence of vitamin D deficiency among healthy infants and toddlers

    Arch Pediatr Adolesc Med

    (2008)
  • (2011)
  • G.A. Plotnikoff

    Weather or not: the importance of vitamin D status monitoring and supplementation

    Minn Med

    (2009)
  • J.P. Lazol et al.

    10-Year case review of nutritional rickets in Children's Hospital of Michigan

    Clin Pediatr (Phila)

    (2008)
  • P.D. Robinson et al.

    The re-emerging burden of rickets: a decade of experience from Sydney

    Arch Dis Child

    (2006)
  • S.F. Ahmed et al.

    Recent trends and clinical features of childhood vitamin D deficiency presenting to a children's hospital in Glasgow

    Arch Dis Child

    (2011)
  • M. Misra et al.

    Vitamin D deficiency in children and its management: review of current knowledge and recommendations

    Pediatrics

    (2008)
  • J.L. St Sauver et al.

    Use of a medical records linkage system to enumerate a dynamic population over time: the Rochester Epidemiology Project

    Am J Epidemiol

    (2011)
  • Cited by (0)

    Grant Support: Research reported in this publication was supported by the National Institute on Aging of the National Institutes of Health under award R01AG034676 and by the Mayo Clinic Department of Family Medicine.

    Potential Competing Interests: Dr Thacher has received honoraria for authoring medical education materials on vitamin D deficiency.

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