The vitamin D grey areas in pediatric primary care.

Very low serum 25-hydroxyvitamin D levels in asymptomatic children living in northeastern Italy

International Journal of Pediatric Endocrinology 2012, 2012:7 doi:10.1186/1687-9856-2012-7
Stefano Mazzoleni (stefano.mazzoleni@sanita.padova.it) Daniela Toderini (daniela.toderini@sanita.padova.it) Chiara Boscardin (chiab29@yahoo.it)
Article type Letter to the Editor; Submission date 24 March 2012; Acceptance date 18 April 2012; Publication date 18 April 2012
1 MD, Pediatra di Libera Scelta, ULSS 16 Regione Veneto, Padova, Italy
2 MD' Endocrinologa' Medico di Medicina Generale' ULSS 16 Regione Veneto' Padova' Italy
3 MD, Borsista Clinica Pediatrica, Universita di Padova, Padova, Italy
4 MD, Polistudio Pediatrico, via G. D'Annunzio 3/A, I-35028 Piove di Sacco (Padova), Italy
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The principal questions about the vitamin D topic are far to be resolved: in which children 25-hydroxyvitamin D blood testing is appropriate and how much cholecalciferol should be given in the absence of the test? Analyzing vitamin D status in a group of children cared by a "family pediatrician" in northeastern Italy we noted a high incidence of deficiency in asymptomatic preschool children without risk factors. As routine vitamin D testing is not recommended in the average risk population the supplementation with cholecalciferol represents a "grey area" mostly in pediatric primary care.

Dear Editor,
we read with interest the article by Bener and Hoffmann on the incidence of nutritional rickets in a sun rich country like Qatar [1], where decreased vitamin D was a major risk factor. Hypovitaminosis D is highly prevalent in children throughout the world [2,3] but it is still not clear what is the best practice in pediatric primary care settings. Michael Holick, a recognized expert on the topic, has stated that "there is no need to measure everybody's blood 25-hydroxyvitamin D" [25(OH)D] and that only patients with particular diseases should be screened for vitamin D insufficiency/deficiency [4]. Although the literature has shown that patients with deficiency are much less frequent than those with insufficiency, it is also remarkable that vitamin D deficiency is often subclinical and depending on local situations; for example it may be associated with overweight [5] or underweight [1]. To our knowledge there are only a few studies on children living in northeastern Italy [6-8]: they have been conducted retrospectively [6] or examining patients afferent to a Pediatric Department [7] or asthmatic [8]. On this basis an analysis of vitamin D status was prospectively conducted in children cared by a "family pediatrician" in a rural area near Padua (45° N latitude). In 65 patients the vitamin D test was included in exams ordered for different reasons (suspected anemia, fatigue, poor growth, etc.) between November 2010 and June 2011. Results were retrieved from 58 children (age range 1.1-15.3 years, median age 6.75 years). Serum 25(OH)D was dosed by chemiluminescence; the laboratory normal range was 75-250 nmol/l (30-99 ng/ml); insufficiency was defined as 25-74 nmol/l (10-29 ng/ml), deficiency as < 25 nmol/l (< 10 ng/ml).

Most of the children (77%) had low serum 25(OH)D levels: 38 of them (66% of all patients) had an insufficiency and 7 (12%) had a deficiency.
Moreover, 29 children (50%) had 25(OH)D < 50 nmol/l (< 20 ng/ml) that is the cut-off recently suggested to diagnose vitamin D deficiency [5,9].

None among the 9 young teens (11-15 years) had a normal value of 25(OH)D and 6 of the 7 children with 25(OH)D < 25 nmol/l (< 10 ng/ml) were between ages 2 and 5 years; this deficiency was asymptomatic in 5/6 cases. Moreover, our children with 25(OH)D > 75 nmol/l (> 30 ng/ml) and those with deficiency didn't differ for exposure to sunlight, food consumption, gender, ethnicity or BMI. Vitamin D status was also irrespective of other blood test results (see Table 1).
Table 1. Vitamin D status of cases based on laboratory reference ranges (white columns) and on recent literature [5,9] (grey columns)

Holick has suggested that "it would be much more cost-effective to implement a vitamin D supplementation program for all children and adults" [4] but the question now is how much vitamin D should be given. If 400 IU cholecalciferol per day may be sufficient in the first year of life [10], much more is needed in older children, assuming that most of them have less or much less than the minimum desirable [11]. Moreover, recommended doses of 600 IU per day [12] probably offer no advantage to children with 25(OH)D < 25 nmol/l (< 10 ng/ml) [13]. Although authoritative guidelines state that routine vitamin D testing is not warranted in the average risk population, the Holick's D-lemma [4] is far from being resolved.

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References

1. Bener A, Hoffmann GF: Nutritional Rickets among Children in a Sun Rich Country. Int JPediatr Endocrinol 2010, 2010:410502. Epub 2010 Oct 27.
2. Mansbach M, Ginde AA, Camargo CA: Serum 25-Hydroxyvitamin D levels among US children aged 1 to ll years: do children need more vitamin D? Pediatrics 2009, 124:1404-1410.
3. Rathi N, Rathi A: Vitamin D and child health in the 21st century. Indian Pediatr 2011, 48:619-625.
4. Holick MF: The D-lemma: To screen or not to screen for 25-Hydroxyvitamin D concentrations. Clin Chem 2010, 56:729-731.
5. Saintonge S, Bang H, Gerber LM: Implications of a new definition of vitamin D deficiency in a multiracial US adolescent population: the National Health and Nutrition Survey III. Pediatrics 2009, 123:797-803.
6. Lippi G, Montagnana M, Targher G: Vitamin D deficiency among Italian children [letter]. CMAJ 2007, 177:1529-1530.
7. Marrone G, Rosso I, Moretti R, Valent F, Romanello C: Is vitamin D status known among children living in Northern Italy? Eur JNutr. 2011 May 4. [Epub ahead of print].
8. Chinellato I, Piazza M, Sandri M, Peroni D, Piacentini G, Boner AL: Vitamin D serum levels and markers of asthma control in Italian children. J Pediatr 2011, 158:437-441. Epub 2010 Sep 26.
9. Holick MF, Vitamin D deficiency. N Engl J Med 2007, 357:266-281.
10. Mutlu GY, Kusdal Y, Ozsu E, Cizmecioglu FM, Hatun S: Prevention of Vitamin D deficiency in infancy: daily 400 IU vitamin D is sufficient. Int J Pediatr Endocrinol 2011, 2011:4. Epub 2011 Jun 28.
11. Vieth R: Why the minimum desirable serum 25-hydroxyvitamin D level should be 75 nmol/L (30 ng/ml). Best Pract Res Clin Endocrinol Metab. 2011, 25:681-691.
12. Abrams SA: Dietary Guidelines for Calcium and Vitamin D: A New Era. Pediatrics 2011,127:566-568.
13. Heaney RP, Davies KM, Chen TC, Holick MF, Barger-Lux MJ: Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr 2003, 77:204-210.
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See also VitaminDWiki

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