Dietary calcium intake influences the relationship between serum 25-hydroxyvitamin D3 (25OHD) concentration and parathyroid hormone (PTH) concentration

Impact of COVID lockdown: Increased prevalence of symptomatic Vitamin D deficiency in adolescents

Background

During the COVID lockdown in India, which lasted for more than a year, all schools were closed and children were homebound. When the lockdown was lifted, we observed an increased prevalence of Vitamin D deficiency(VDD) in adolescents. We want to highlight the effect of home lockdown on adolescents, which can predispose such children to VDD.

Aim

To document the increased prevalence of symptomatic VDD in adolescents after COVID lockdown and to study the symptoms, biochemical abnormalities, and response to therapy in this subset.

Methods

This prospective observational study was done from November 2021 to May 2022 with a minimum follow-up of six months.

Inclusions

Consecutive children presenting with gait abnormalities, proximal myopathy, and pains, with documented VDD. Exclusion: Genetic, neuromuscular disorders, juvenile rheumatoid arthritis, chronic renal failure, thyroid disorders and those on anti-epileptic medications and vitamin D supplementation in the past 6 months were excluded from the study. We recorded the symptomatology, biochemical abnormalities, and muscle weakness and followed their improvement after Vitamin D and Calcium supplementation.

Results

A statistically significant increase in symptomatic VDD in adolescents, in six months post-lockdown was noted. Thirty-one adolescents between 9 to 14 years were studied. All cases were relieved of pain and muscle power normalized in 12 weeks.

Conclusion

Prolonged house arrest may cause VDD in adolescents. Physicians should consider VDD in adolescents with myopathy and pain after pandemic lockdowns. Supplementation of Vitamin D and calcium resolves most symptoms except deformities. Follow-up is needed until growth spurt completion for recurrence of symptoms.

Optimal 25-OH-Vitamin D Level in Children Derived From Biochemical Parameters

The aim of the study was to evaluate the bone-optimal pediatric levels of 25-hydroxy-vitamin D (25OHD) by testing the level at which 25OHD optimally effects calcium, phosphorus, and parathyroid hormone levels in a large population-based dataset. This was an observational retrospective "big-data" study. We analyzed 49 935 25OHD tests from children sampled in Clalit Health Services, Jerusalem district between 2009 and 2019. Associated data were available in the following number of samples: corrected calcium; 18 869, phosphorus: 1241, and PTH: 449. We tested correlations between each parameter and 25OHD, adjusting phosphorus levels by age using a "phosphorus index". Pearson's and Spearman's correlation coefficients were calculated to determine the strength of the correlation between 25OHD and each parameter. There was a significant correlation between 25OHD levels and both PTH and calcium but not for the phosphorus index. The level at which increase in 25OHD continued to cause significant alteration was: for PTH up to 100 nmol/l (40 ng/ml), for corrected calcium it increased beyond 100 nmol/l. Increasing levels of 25OHD levels up to at least 100 nmol/l are associated with improvement in parameters known to be associated with increased bone mineralization. Therefore, one should aim for a 25OHD level of 100 nmo/l.

The role of dietary calcium in the etiology of childhood rickets in the past and the present

For more than two centuries, lack of sunlight has been understood to cause vitamin D deficiency and documented as a primary cause of rickets. As such, evidence of rickets in the archeological record has been used as a proxy for vitamin D status in past individuals and populations. In the last decade, a clinical global consensus has emerged wherein it is recognized that dietary calcium deficiency also plays a role in the manifestation of rickets and classic skeletal deformities may not form if dietary calcium is normal even if vitamin D is deficient. This disease is now clinically called "nutritional rickets" to reflect the fact that rickets can take calcium deficiency-predominant or vitamin D deficiency-predominant forms. However, there are currently no paleopathological studies wherein dietary calcium deficiency is critically considered a primary etiology of the disease. We review here the interplay of calcium, vitamin D, and phosphorous in bone homeostasis, examine the role of dietary calcium in human health, and critically explore the clinical literature on calcium deficiency-predominant rickets. Finally, we report a case of rickets from the late Formative Period (~2500-1500 years ago) of the Atacama Desert and argue the disease in this infant is likely an example of calcium deficiency-predominant rickets. We conclude that most archeological cases of rickets are the result of multiple micronutrient deficiencies that compound to manifest in macroscopic skeletal lesions. For clinicians, these factors are important for implementing best treatment practice, and for paleopathologists they are necessary for appropriate interpretation of health in past communities.

The Relationship between Dietary Calcium and Age-Related Macular Degeneration

BACKGROUND

Mineral element supplements are widely used in the older adult population. However, little is known of their impact on the progression of age-related macular degeneration (ARMD). The aim of this study was to examine the association between dietary micronutrients and ARMD in older adults.

METHODS

We enrolled 5227 participants from the National Health and Nutrition Examination Survey (NHANES 2005-2008) in this cross-sectional study. ARMD was evaluated using an ophthalmic digital imaging system and digital camera. Mineral element consumption was collected using a 24-hour dietary recall. The association between mineral element use and the presence of ARMD was determined by multivariable logistic regression.

RESULTS

After adjusting for relevant variables, dietary calcium was negatively associated with ARMD (OR: 680, 95%CI: 0.482-0.960). In contrast to dietary form, serum concentration of calcium was not associated with ARMD. Moreover, increased dietary calcium was associated with reduced ARMD (OR: 0.684, 95%CI: 0.468-1.000).

CONCLUSION

A lower consumption of dietary calcium was significantly associated with a higher risk of ARMD. Further longitudinal studies are necessary to explore these findings.

Calcium status assessment at the population level: Candidate approaches and challenges

Inadequate dietary calcium intake is a global public health problem that disproportionately affects low- and middle-income countries. However, the calcium status of a population is challenging to measure, and there are no standard methods to identify high-risk communities even in settings with an elevated prevalence of a disease caused or exacerbated by low calcium intake (e.g., rickets). The calcium status of a population depends on numerous factors, including intake of calcium-rich foods; the bioavailability of the types of calcium consumed in foods and supplements; and population characteristics, including age, sex, vitamin D status, and genetic attributes that influence calcium retention and absorption. The aim of this narrative review was to assess candidate indicators of population-level calcium status based on a range of biomarkers and measurement methods, including dietary assessment, calcium balance studies, hormonal factors related to calcium, and health outcomes associated with low calcium status. Several promising approaches were identified, but there was insufficient evidence of the suitability of any single indicator to assess population calcium status. Further research is required to develop and validate specific indicators of calcium status that could be derived from the analysis of data or samples that are feasibly collected in population-based surveys.

Vitamin D status and determinants in Indian children and adolescents: a multicentre study

Studies performed on Indian children to assess vitamin-D status have been on small sample sizes, limited to specific geographical locations and used non-standard methods to measure 25(OH)D₃. This multicentre study assessed 25(OH)D₃ concentrations from dried blood spots (DBS) in 5–18-year-old Indian children and adolescents using a standardized protocol and identified factors contributing towards vitamin D deficiency. Cross-sectional, observational school-based study was conducted by multi-stage stratified random sampling. A city and nearby village were selected from 6 Indian states covering wide geographical areas. Demography, anthropometry, body-composition, dietary-intakes and DBS samples were collected. 25(OH)D₃ was assessed from DBS using Liquid chromatography with tandem-mass spectrometry. Vitamin-D status was assessed in 2500 children; with additional data collected on a subset (n = 669) to assess predictors. Mean vitamin-D concentration was 45.8 ± 23.9 nmol/L, 36.8% of subjects had sufficient vitamin-D (> 50 nmol/L); rural subjects and boys had higher concentrations (p < 0.05). On regression analysis, younger age, female-gender, overweight and urban residence significantly contributed to deficiency. More than half the Indian children/adolescents were vitamin-D deficient or insufficient. Our study reinforces vitamin-D deficiency as a major public health problem and the need for supplementation, food fortification and educating the population as initiatives required to improve sufficiency status.

High burden of hypovitaminosis D among the children and adolescents in South Asia: a systematic review and meta-analysis

BACKGROUND

Vitamin D is vital for the growth and development of children. While deficiency and/or insufficiency of vitamin D among South Asian children are frequently reported in the literature, the lack of a meta-analysis has left its true extent poorly characterized. In this study, we aimed to conduct a systematic review and perform meta-analyses of the prevalence of hypovitaminosis D among the children of the South Asian countries.

METHODS

Two major electronic search engines (PubMed and Scopus) and one database (Google scholar) were used; original studies, conducted among South Asian children and adolescents and published between 1 January 2001 and 31 December 2019. A random-effect meta-analysis was also performed to calculate the pooled prevalence of hypovitaminosis D followed by subgroup analyses for countries and age groups.

RESULTS

After applying inclusion and exclusion criteria, a total of 41 studies with a total population size of 18,233 were finally selected. The overall prevalence of hypovitaminosis D was 61% [95% CI: 46% to 71%] with highly significant heterogeneity (I2 = 99.72%; p < 0.0001). The average level of serum vitamin D ranged from 5 ng/mL to 34 ng/mL, with a weighted mean of 19.15 ng/mL (weighted standard deviation 11.59 ng/mL). Country-wise analysis showed that hypovitaminosis D in Afghanistan was the highest [96.2%; 95% CI: 91% to 99%], followed by Pakistan [94%; 95% CI: 90% to 96%], India [64%; 95% CI: 46% to 79%], Bangladesh [35.48%; 95% CI: 32% to 39%], Nepal [35%; 95% CI: 1% to 83%], and Sri Lanka [25%; 95% CI: 16% to 36%]. Age group analyses revealed that hypovitaminosis D was most prevalent among neonates [85%; 95% CI: 76% to 91%], followed by school-going children [57%; 95% CI: 33% to 80%], and preschool children [55%; 95% CI: 35% to 75%].

CONCLUSION

This study generates quantitative evidence and specific extent of hypovitaminosis D in the South Asian countries as a public health concern. Being the first systematic review for this region, results from this study will create awareness and will facilitate adopting mitigation strategies by the policymakers and the governments to address this problem.

Is dietary deficiency of calcium a factor in rickets? Use of current evidence for our understanding of the disease in the past

OBJECTIVE

Rickets is considered an indicator of vitamin D deficiency in palaeopathology, but a strand of biomedical thought maintains that dietary calcium deficiency may sometimes play a part in its causation. Our aim is to evaluate the extent to which low calcium intake should be considered as a factor in biocultural interpretations of rickets.

METHODS

We assess published modern epidemiological studies that provide primary data to support claims for a role for dietary calcium deficiency in rickets. We also consider how we might identify, via indicators of calcium intake, populations at risk of calcium deficiency in the past.

RESULTS

Support for dietary calcium deficiency as a cause of rickets is equivocal. Direct measurement of dietary calcium in the past is not possible, but exposure to risk factors for low calcium intake can to some extent be identified.

CONCLUSION

Whilst there is little evidence to alter the view that rickets is essentially an indicator of a population's vitamin D status, occasionally, in very low calcium intake groups, dietary calcium deficiency may play a synergistic role by accentuating the need for vitamin D.

SIGNIFICANCE

The notion that dietary calcium deficiency may be a cause of rickets appears to be gaining currency in bioarchaeological studies. This paper shows that it is unusual for this to be the case, and even then the role of vitamin D remains crucial.

LIMITATIONS

This paper attempts to summarise the current state of biomedical study in an area that is subject to continuing investigation.

Environmental Factors That Affect Parathyroid Hormone and Calcitonin Levels

Calciotropic hormones, parathyroid hormone (PTH) and calcitonin are involved in the regulation of bone mineral metabolism and maintenance of calcium and phosphate homeostasis in the body. Therefore, an understanding of environmental and genetic factors influencing PTH and calcitonin levels is crucial. Genetic factors are estimated to account for 60% of variations in PTH levels, while the genetic background of interindividual calcitonin variations has not yet been studied. In this review, we analyzed the literature discussing the influence of environmental factors (lifestyle factors and pollutants) on PTH and calcitonin levels. Among lifestyle factors, smoking, body mass index (BMI), diet, alcohol, and exercise were analyzed; among pollutants, heavy metals and chemicals were analyzed. Lifestyle factors that showed the clearest association with PTH levels were smoking, BMI, exercise, and micronutrients taken from the diet (vitamin D and calcium). Smoking, vitamin D, and calcium intake led to a decrease in PTH levels, while higher BMI and exercise led to an increase in PTH levels. In terms of pollutants, exposure to cadmium led to a decrease in PTH levels, while exposure to lead increased PTH levels. Several studies have investigated the effect of chemicals on PTH levels in humans. Compared to PTH studies, a smaller number of studies analyzed the influence of environmental factors on calcitonin levels, which gives great variability in results. Only a few studies have analyzed the influence of pollutants on calcitonin levels in humans. The lifestyle factor with the clearest relationship with calcitonin was smoking (smokers had increased calcitonin levels). Given the importance of PTH and calcitonin in maintaining calcium and phosphate homeostasis and bone mineral metabolism, additional studies on the influence of environmental factors that could affect PTH and calcitonin levels are crucial.

The association of minerals intake in three meals with cancer and all-cause mortality: the U.S. National Health and Nutrition Examination Survey, 2003-2014

BACKGROUND

Intake time of diet has recently been demonstrated to be associated with the internal clock and circadian pattern. However, whether and how the intake time of minerals would influence the natural course of cancer was largely unknown.

METHODS

This study aimed to assess the association of mineral intake at different periods with cancer and all-cause mortality. A total of 27,455 participants aged 18-85 years old in the National Health and Nutrition Examination Survey were recruited. The main exposures were the mineral intakes in the morning, afternoon and evening, which were categorized into quintiles, respectively. The main outcomes were mortality of cancer and all causes.

RESULTS

During the 178,182 person-years of follow-up, 2680 deaths, including 601 deaths due to cancer, were documented. After adjusting for potential confounders, compared to the participants who were in the lowest quintile(quintile-1) of mineral intakes at dinner, the participants in the highest quintile intake(quintile-5) of dietary potassium, calcium and magnesium had lower mortality risks of cancer (HRpotassium = 0.72, 95% CI:0.55-0.94, P for trend = 0.023; HRcalcium = 0.74, 95% CI:0.57-0.98, P for trend = 0.05; HRmagnesium = 0.75, 95% CI:0.56-0.99, P for trend = 0.037) and all-cause (HRpotassium = 0.83, 95% CI:0.73-0.94, P for trend = 0.012; HRcalcium = 0.87, 95% CI:0.76-0.99, P for trend = 0.025; HRmagnesium = 0.85, 95% CI:0.74-0.97, P for trend = 0.011; HRcopper = 0.80, 95%CI: 0.68-0.94, P for trend = 0.012). Further, equivalently replacing 10% of dietary potassium, calcium and magnesium consumed in the morning with those in the evening were associated with lower mortality risk of cancer (HRpotassium = 0.94, 95%CI:0.91-0.97; HRcalcium = 0.95, 95%CI:0.92-0.98; HRmagnesium = 0.95, 95%CI: 0.92-0.98).

CONCLUSIONS

This study demonstrated that the optimal intake time of potassium, calcium and magnesium for reducing the risk of cancer and all-cause mortality was in the evening.

The Association Between Dietary Inflammatory Index and Parathyroid Hormone in Adults With/Without Chronic Kidney Disease

Aims: We aimed to assess the association between dietary inflammation index (DII) with parathyroid hormone (PTH) and hyperparathyroidism (HP) in adults with/without chronic kidney disease (CKD).

Methods: Data were obtained from the 2003–2006 National Health and Nutrition Examination Survey (NHANES). The participants who were <18 years old, pregnant, or missing the data of DII, PTH, and CKD were excluded. DII was calculated based on a 24-h dietary recall interview for each participant. Weighted multivariable regression analysis and subgroup analysis were conducted to estimate the independent relationship between DII with PTH and the HP in the population with CKD/non-CKD.

Results: A total of 7,679 participants were included with the median DII of −0.24 (−2.20 to 1.80) and a mean PTH level of 43.42 ± 23.21 pg/ml. The average PTH was 45.53 ± 26.63 pg/ml for the participants in the highest tertile group compared with 41.42 ± 19.74 pg/ml in the lowest tertile group (P < 0.0001). The rate of HP was 11.15% overall, while the rate in the highest DII tertile was 13.28 and 8.60% in the lowest DII tertile (P < 0.0001). The participants with CKD tended to have higher PTH levels compared with their counterparts (61.23 ± 45.62 vs. 41.80 ± 19.16 pg/ml, P < 0.0001). A positive association between DII scores and PTH was observed (β = 0.46, 95% CI: 0.25, 0.66, P ≤ 0.0001), and higher DII was associated with an increased risk of HP (OR = 1.05, 95% CI: 1.02, 1.08, P = 0.0023). The results from subgroup analysis indicated that this association was similar in the participants with different renal function, gender, age, BMI, hypertension, and diabetes statuses and could also be appropriate for the population with CKD.

Conclusions: Higher consumption of a pro-inflammatory diet appeared to cause a higher PTH level and an increased risk of HP. Anti-inflammatory dietary management may be beneficial to reduce the risk of HP both in the population with and without CKD.

Combined Effects of Vitamin D Status, Renal Function and Age on Serum Parathyroid Hormone Levels

BACKGROUND

Vitamin D status and renal function are well-known independent predictors of serum parathyroid hormone (PTH) levels. We aimed to describe the combined effects of 25-hydroxy vitamin D (25(OH)D), glomerular filtration rate (GFR) and age on serum PTH levels across the whole clinical spectrum.

METHODS

We retrieved from our endocrinology center database all PTH measurement between 2012 and 2020 for which a simultaneous measurement of serum 25(OH)D, calcium and creatinine was available. Age, sex and diagnosis were available for all subjects. Intact PTH was measured using the same electrochemiluminescence assay.

RESULTS

There were 6,444 adults and 701 children without a diagnosis of hyper- or hypoparathyroidism or abnormal serum calcium levels. In adults with 25(OH)D≥12 ng/mL multiple regression models showed that serum PTH was negatively correlated with both 25(OH)D and GFR. Regression (-0.68 and -1.59 vs. -0.45 and -0.22 respectively), partial correlation (-0.16 and -0.35 vs. -0.12 and -0.10 respectively) and determination coefficients (0.14 vs. 0.031) were higher in CKD than in normal renal function. In subjects with 25(OH)D<12 ng/mL, GFR was the only significant predictor in those with CKD (β-coefficient=-2.5, r=-0.55) and 25(OH)D was the only significant predictor in those with normal renal function (β-coefficient=-2.05, r=-0.11). Increasing age was associated with higher PTH levels only in those with normal renal function and 25(OH)D≥12 ng/mL.

CONCLUSIONS

We showed that declining vitamin D and renal function have additive effects on serum PTH in subjects without vitamin D deficiency. In vitamin D deficient subjects this dependency is stronger but is not additive anymore.

Prevalence and Determinants of a Blunted Parathyroid Hormone Response in Young Saudi Women with Vitamin D Deficiency: A Cross-Sectional Study

Vitamin D deficiency is highly prevalent among the Saudi population. Increased parathyroid hormone (PTH) secretion is an appropriate homeostatic response to correct the resultant hypocalcemia. However, not all vitamin D deficiency patients have increased PTH levels. This study determined the prevalence of a blunted PTH response to vitamin D deficiency among apparently healthy young Saudi women and assessed anthropometric and biochemical factors associated with this response by performing a secondary analysis of data obtained from a cross-sectional study conducted at the "Center of Excellence for Osteoporosis research." Overall, 315 women (aged 20-45 years) with vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) levels <30 nmol/L) were included. They were divided into two groups according to the laboratory cutoff value of PTH (<7 or ≥7 pmol/L), and anthropometric and biochemical characteristics of both groups were compared. Women with a blunted PTH response (n = 62, 19.7%) had a significantly lower body mass index (BMI) (P < 0.001) and smaller waist circumference (P=0.001). They also had significantly higher serum 25(OH)D (P=0.001), corrected serum calcium (P < 0.001), and phosphate (P=0.003) levels than those with an elevated PTH response (n = 253, 80.3%). Multiple logistic regression analysis showed that lower BMI (OR = 0.925; 95% CI: 0.949-0.987) and higher 25(OH)D (OR = 1.068; 95% CI: 1.014-1.124) and serum calcium (OR = 8.600; 95% CI: 1.614-45.809) levels were significantly associated with a blunted PTH response (R ² = 0.178). A blunted PTH response to vitamin D deficiency is mainly observed among women with lower BMI. Higher serum calcium and 25(OH)D levels and lower BMI were significant predictors of a blunted PTH response, which may indicate that these subjects are adapting to lower 25(OH)D levels and maintaining normal calcium levels without the need to increase PTH secretion. The mechanisms underlying this adaptation are unclear, and future studies to explore these mechanisms are warranted.

Seasonal periodicity of serum parathyroid hormone and its relation with vitamin D in Romania

We measured serum parathyroid hormone in 8409 Romanian subjects and found a mild seasonal variation with highest levels in March and lowest levels in September. PTH was dependent on serum vitamin D, particularly below 12.82 ng/mL. Together, these suggest that vitamin D supplementation is warranted only in at-risk groups.

PURPOSE

Seasonal variation of parathyroid hormone (PTH) and its dependency on serum 25-hydroxy vitamin D (25(OH)D) levels are well-described. However, there are few studies from Europe, and genetic, nutritional, and cultural differences are important. We describe the seasonal variation of serum PTH and its relation with serum 25(OH)D levels in Romania.

METHODS

We retrieved from our endocrinology center database all PTH measurements between 2011 and 2019 together with age, sex, diagnosis, and date of blood sampling. Simultaneous serum 25(OH)D levels were partially available. Intact PTH was measured using the same electrochemiluminescence assay.

RESULTS

There were 8409 subjects (median age 49 (36, 60) years; 20.5% men) without a diagnosis of hyperparathyroidism (primary or secondary to chronic kidney disease), hypoparathyroidism, or low bone mass. Serum PTH showed a mild seasonal variation with highest levels at the end of March (47.61 pg/mL) and lowest levels at the end of September (43.15 pg/mL). All sex and age subgroups showed highest levels in the spring and lowest levels in the fall. Males had significantly lower PTH levels than females irrespective of season. PTH correlated inversely with serum 25(OH)D with a breakpoint of 12.82 ng/mL in 2800 subjects who had a simultaneous measurement of 25(OH)D. Increasing age was associated with increasing PTH levels independently of serum 25(OH)D.

CONCLUSIONS

We showed a mild seasonal variation of serum PTH in Romania, at an inverse sinusoidal pattern than serum 25(OH)D. The breakpoint on the PTH-25(OH)D correlation suggests that vitamin D supplementation is warranted only in at-risk groups.

Serum PTH is not a good marker for defining a threshold for vitamin D deficiency

OBJECTIVE

In addition to its skeletal effects, vitamin D may also be important for health in general. It is uncertain what level of serum 25-hydroxyvitamin D (25(OH)D), marker of vitamin D status, is sufficient for these effects. With decreasing serum 25(OH)D levels there is an increase in serum PTH. The point at which this occurs has been considered as a threshold for vitamin D sufficiency. The thresholds found have varied widely and have mainly been based on observational studies. However, to truly establish a threshold for vitamin D effects, this has to be based on randomized controlled trials (RCTs).

METHODS

The study included 2803 subjects from a general health survey, the Tromsø study, and pooled individual person data from five vitamin D intervention studies (n = 1544). Serum parathyroid hormone (PTH) and change in PTH after vitamin D supplementation were related to serum 25(OH)D levels in steps of 25 nmol/L (<24, 25-49, 50-74, 75-99, and >99 nmol/L).

RESULTS

In the Tromsø study, in the females there was a gradual decrease in serum PTH with increasing serum 25(OH)D with no apparent plateau, whereas in the males the decrease in PTH in subjects with serum 25(OH)D >74 nmol/l was marginal. In pooled RCTs, there was a significant reduction in serum PTH by vitamin D supplementation regardless of baseline serum 25(OH)D level.

CONCLUSIONS

The use of the serum PTH-25(OH)D relation from observational studies to determine a threshold for vitamin D sufficiency is highly questionable.

A systematic review and meta-analysis of prevalence of vitamin D deficiency among adolescent girls in selected Indian states

BACKGROUND:

Vitamin D deficiency among adolescents is an emerging public health priority as adolescence marks a period of rapid growth and the onset of the reproductive phase. However, lack of national prevalence data and intervention strategies is of public health concern.

OBJECTIVE:

The objective of this study was to determine the pooled prevalence of vitamin D deficiency among adolescent girls in selected Indian states.

METHODS:

A systematic literature review was performed using three different search engines. The searches yielded nine eligible articles. Study quality was assessed for 10 different criteria. Meta-analysis was performed to estimate pooled prevalence of vitamin D deficiency among adolescent girls and to assess the heterogeneity among selected studies.

RESULTS:

A sample of n=1352 was used to study prevalence among adolescent girls. The random effects combined estimate for overall prevalence was 25.70% (95% CI 3.89-2137.9). High heterogeneity (tau²=1.71, I²=100%) was observed and seven out of nine studies showed low to moderate risk and two showed high risk of bias. The test for overall effect was observed to be Z=0.77 ( p=0.44).

CONCLUSIONS:

High prevalence of vitamin D deficiency among adolescent girls identifies the need to introduce screening of adolescents and introduce proven public-health interventions such as fortification of foods to address deficiency.

Vitamin D deficiency in immigrants

Vitamin D deficiency and rickets are more common in non-western immigrants and refugees than in the native population. Severe vitamin D deficiency (serum 25-hydroxyvitamin D <25 nmol/l) may occur in up to 50% of children and adults of non-western origin. They are not used to sunshine exposure due to the often excessive sunshine in the country of origin. They usually have a more pigmented skin. Non-western immigrants and refugees often wear skin-covering clothes due to religious or cultural tradition. The food contains little vitamin D with the exception of fatty fish. In addition, many immigrants have a low calcium intake. Complaints may include fatigue, pain in shoulders, ribs, lower back and thighs. Neonates and young children may have spasms and convulsions due to hypocalcemia. Older children and adolescents may have bone pain, muscle weakness and skeletal deformities. Widening of the wrist, chest deformities and bowing of the legs may occur, and longitudinal growth is delayed. In adults, muscle weakness and bone pain are predominant. Laboratory examination may show hypocalcemia and hypophosphatemia and elevated alkaline phosphatase. The serum 25(OH)D is below 25 nmol/l in case of severe vitamin D deficiency with symptoms. Impaired 25-hydroxylation or 1α-hydroxylation may occur in case of severe liver or renal disease or by genetic causes. Radiographs of wrists or knees may show widening of the growth plates and cupping of radius and ulna may confirm the diagnosis. In adolescents and adults, radiographs of painful bones may show pseudofractures or Looser zones. Rickets and osteomalacia are treated by vitamin D3 2000 IU/d in infants, 3000-6000 IU/d in older children in combination with calcium 500 mg /d. In osteomalacia, the adult vitamin D3 dose is 2000-3000 IU/d, combined with calcium 1000-2000 mg/d. Prevention of vitamin D deficiency can be done with vitamin D3 400-800 IU/d, depending on age. Nutritional measures include fortification of milk or other foods.

The roles of vitamin D and dietary calcium in nutritional rickets

The etiology and pathogenesis of nutritional rickets are becoming progressively clearer. Vitamin D deficiency has generally been considered the major or only player in the pathogenesis of nutritional rickets. However, recent research into calcium deficiency has now provided clinicians with reasons to investigate and manage patients with nutritional rickets more appropriately.

The important question when assessing cases of nutritional rickets is: “Is it calcium or vitamin D deficiency or both that play a major role in the pathogenesis of the disease?”

The case presentation in this review highlights the risk factors, clinical presentation and pathophysiology of nutritional rickets in a young South African black child from a semi-urban area in Johannesburg, a city with abundant sunshine throughout the year.

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Vitamin D and calcium deficiencies play synergistic roles in nutritional rickets.

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Dietary calcium intake of <300 mg/day increases the risk of nutritional rickets.

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Vitamin D status is worsened by dietary calcium deficiency itself.

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Marked elevation of 1,25-dihydroxyvitamin D is characteristic of calcium deficiency.

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Preventative strategies needed to decrease the prevalence of nutritional rickets.

Association of dental and skeletal fluorosis with calcium intake and serum vitamin D concentration in adolescents from a region endemic for fluorosis

CONTEXT

Fluorosis is controlled by the duration of fluoride exposure and calcium and Vitamin D nutrition status.

AIM

To examine (a) prevalence of dental and skeletal fluorosis in adolescents from upper, middle, and lower socioeconomic strata (SES) and (b) association of fluorosis with calcium intake and Vitamin D status.

SETTINGS AND DESIGN

A cross-sectional study conducted in 10-13.9 years apparently healthy adolescents (n = 90), from different SES of Patan (Gujarat, India).

MATERIALS AND METHODS

Dental fluorosis was graded as mild, moderate, and severe. Radiographs of the right hand and wrist were examined and graded. Serum 25 hydroxyvitamin D3 (25OHD) and parathyroid hormone concentrations were measured. Diet was recorded (24 h recall) and calcium intake was computed (C-diet V-2.1, 2013, Xenios Technologies Pvt. Ltd).

STATISTICAL ANALYSIS

Generalized linear model was used to analyze relationships between fluorosis, SES, serum 25OHD concentration, and calcium intake.

RESULTS

Fluorosis was predominant in lower SES (17% had both dental and radiological features whereas 73% had dental fluorosis); no skeletal deformities were observed. Mean 25OHD concentrations and dietary calcium were 26.3 ± 4.9, 23.4 ± 4.7, and 18.6 ± 4 ng/ml and 441.2 ± 227.6, 484.3 ± 160.9, and 749.2 ± 245.4 mg/day, respectively, for lower, middle, and upper SES (P < 0.05). Fluorosis and SES showed a significant association (exponential β = 2.5, P = 0.01) as compared to upper SES, middle SES adolescents were at 1.3 times while lower SES adolescents were at 2.5 times higher risk. Serum 25OHD concentrations (P = 0.937) and dietary calcium intake (P = 0.825) did not show a significant association with fluorosis.

CONCLUSION

Fluorosis was more common in lower SES adolescents, probably due to the lack of access to bottled water. Relatively adequate calcium intake and serum 25OHD concentrations may have increased the efficiency of dietary calcium absorption, thus preventing severe fluorosis.

Prevalence and determinants of vitamin D deficiency in healthy French adults: the VARIETE study

The U.S. Institute of Medicine considers that a serum 25-hydroxyvitamin D (25OHD) concentration >20 ng/mL corresponds to optimal vitamin D status in the general population. Old studies of vitamin D status in the French general population have demonstrated high prevalence of insufficiency. We measured serum 25OHD, 1,25(OH)2D, PTH, calcium, phosphorus, and creatinine levels in 892 French Caucasian healthy subjects (463 men, 429 women) aged from 18 to 89 years. The 25OHD concentration was similar in men (24.1 ± 8.2 ng/mL) and women (23.4 ± 8.0 ng/mL). 25OHD concentrations of <10, <12, <20, and <30 ng/mL were found in respectively 6.3, 9.9, 34.6, and 80.3 % of subjects. Residence in northern France (odds ratio [OR] 1.91), blood sampling between January and March (OR 7.74), BMI ≥24 kg/m(2) (OR 1.81), and age 60 years or more (OR 1.99) were significant determinants of hypovitaminosis D (25OHD <20 ng/mL). The serum 25OHD level correlated positively with 1,25(OH)2D and negatively with PTH. 25OHD values below 20 ng/mL were associated with lower 1,25(OH)2D levels, and 25OHD values below 27 ng/mL were associated with higher PTH levels. Many French healthy adults have a 25OHD concentration <20 ng/mL, especially during winter months. Actions to improve the vitamin D status of the French general population are urgently needed.