Introduction
Rickets and Osteomalacia—Definition, Risk Groups and Terminology
Definition
Risk Groups
Terminology De-confused
Calcium Deprivation: Concept and Clinical Spectrum
The Concept of Calcium Deprivation
The Clinical Spectrum of Calcium Deprivation from Conception to Old Age
Sufficient Dietary Calcium and Vitamin D, and Treatment of Rickets
How Much Vitamin D and Dietary Calcium is Enough?
Management of NR
Prevention and Public Health
Identification of Risk Groups is Straightforward
Effective Prevention
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400 IU (10 μg) daily for all infants regardless of mode of feeding, from birth to a minimum of 12 months of age.
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600 IU (15 μg) daily during pregnancy (alongside iron and folic acid).
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600 IU daily lifelong in risk groups, including individuals with dark skin, full body clothing, limited sun exposure either due to geographic location, limited outdoor activity or restricted mobility, low socioeconomic background and poor diet. Individuals at risk should also meet the daily minimum requirement for sufficient calcium intake (Table 1).
Monitored Supplementation of Pregnant Women
Universal Supplementation of Infants Regardless of Mode of Feeding
Supplementation Beyond the First Year of Life
Topic | Revised concepts |
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Calcitriol is not vitamin D | Like cholesterol is biochemically modified by the human body to form active steroid hormones, vitamin D is modified to form the hormone calcitriol. Calcitriol acts on the calcitriol receptor (VDR), whilst vitamin D and 25OHD are biologically inert. |
Calcium deprivation and its complications | Calcium deprivation occurs secondary to low dietary calcium and/or low vitamin D. Calcium deprivation has hypocalcaemic (seizures, tetany and cardiomyopathy) and late hypophosphataemic (rickets, osteomalacia and muscle weakness) complications. |
What to measure and how to make a diagnosis | 25OHD is a good marker of vitamin D status but serum calcium is a poor marker of calcium status. Consistent and early biochemical markers for diagnosis of rickets and osteomalacia are elevations in serum ALP and PTH. The diagnosis of rickets requires radiological confirmation. |
High prevalence in risk groups | NR/osteomalacia is less common in the white population but a common disease in ethnic risk groups with dark skin or cultural full body clothing, including refugees. These groups require lifelong supplementation and/or food fortification programmes. |
Measuring 25OHD and indication for supplementation | Measuring 25OHD is not required in asymptomatic individuals. Instead, lifelong supplementation should be recommended based on ethnicity, culture and other risk factors for calcium deprivation. |
Prevention and supplementation | Universal supplementation of pregnant women and infants with vitamin D is an essential public health strategy, as the foetus and infant have a human right to be protected against harm. The recommendation is now to supplement all infants regardless of skin colour or feeding status with 400 IU/day in the first year of life and longer in those with persistent risk factors (i.e. dark skin). |
Micronutrient deficiencies rarely occur in isolation | In high-risk groups and malnourished individuals, vitamin D deficiency often occurs combined with other micronutrient deficiencies, in particular iron and folate deficiency. |