Effect of vitamin D and calcium supplementation on bone ... - Nature

European Journal of Clinical Nutrition (2006) 60, 605–609

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ORIGINAL ARTICLE

Effect of vitamin D and calcium supplementation on bone turnover in institutionalized adults with Down’s Syndrome P Zubillaga, A Garrido, I Mugica, J Ansa, R Zabalza and JI Emparanza Fundacion Uliazpi, Portu-Etxe 53, 20018 San Sebastiań, Gipuzkoa, Spain

Objective: To assess the status of vitamin D and the effects of calcium and vitamin D3 supplementation on the bone metabolism in a group of adults with Down’s syndrome (DS). Design: Randomized, parallel, controlled and open clinical trial. Setting: Institution for mentally handicapped: Fundacioń Uliazpi, Diputacioń Foral de Guipu´zcoa, San Sebastiań, Spain. Subjects: A total of 23 persons with DS, residents at the Uliazpi Foundation were recruited and all completed the study. Intervention: In all, 12 participants were randomly allocated to receive 1 g of calcium and 800 IU of vitamin D once daily for 1 year while 11 were assigned to the control group, receiving no supplementation. Results: We found no differences between groups regarding serum calcium and phosphorous levels. The remaining parameters showed differences between the two groups consistent with a beneficial effect of the intervention: serum levels of parathyroid hormone, osteocalcin and crosslaps diminished while serum 25 OH vitamin D3 level increased. Conclusions: The results obtained allow to include people with DS as a risk group with regards to vitamin D deficit, which that can be corrected with vitamin D and calcium supplementation, and giving rise to an improvement of the biochemical markers related to the phospho-calcium metabolism and bone remodelling. Sponsorship: This study was sponsored by de Uliazpi Foundation, a public entity devoted to the study and care of persons with intellectual disability who require extensive and pervasive support.

European Journal of Clinical Nutrition (2006) 60, 605–609. doi:10.1038/sj.ejcn.1602357; published online 14 December 2005 Keywords: Down’s syndrome; vitamin D deficiency; calcium; osteoporosis

Introduction Down’s syndrome (DS) is the result of a chromosomal alteration, one of whose characteristics is premature ageing and the appearance of related disorders. The health requirements of individuals with this syndrome have been the object of a number of different recommendations relating to both their growth and developmental phase (American Academy of Pediatrics Committee on Genetics, 2001) and their adult life (Van Allen et al., 1999). Osteoporosis is defined as a skeletal disorder characterized by compromised Correspondence: Dr P Zubillaga, Fundacioń Uliazpi, Bera-Bera94, 61 dcha., San Sebastiań, Gipuzkoa 20009, Spain. E-mail: [email protected] Guarantors: P Zubillaga, A Garrido and JI Emparanza. Contributors: IM, JA and RZ. Received 5 April 2005; revised 6 October 2005; accepted 12 October 2005; published online 14 December 2005

bone strength predisposing a person to an increased risk of fracture (NIH Consensus Development Panel on Osteoporosis, 2001). It is considered an increasingly important public health problem due to both its frequency (one out of every four women and one out of every eight men with ages above 50) and because of its medical, social and economic implications (Hanley and Josse, 1996). Its prevention and treatment are based on adequate sunlight exposure, physical activity, avoidance of harmful habits (smoking, alcohol) and dietetic and pharmacological measures. The administration of calcium supplements reduces the loss of bone mineralization in postmenopausal women (Dawson-Hughes et al., 1990) an effect also observed in relation to the administration of vitamin D3 (Dawson-Hughes et al., 1995). The combination of calcium and vitamin D3 as an isolated treatment has been shown to be effective in reducing bone fracture risks in elderly persons (Chapuy et al., 1992; Dawson-Hughes et al., 1997). All this renders calcium and

Effect of vitamin D and calcium supplementation P Zubillaga et al

606 vitamin D3 supplements highly recommendable for preventing osteoporosis, either alone or in conjunction with other medications. A number of different studies have demonstrated the greater frequency of osteopenia and osteoporosis in people with mental retardation, with special reference to DS patients (Center et al., 1998; Sepu´lveda et al., 1998; Tyler et al., 2000; Jaffe and Timell, 2003). In a previous study carried out with a group of patients residents in our institution we found that osteoporosis occurs with particular frequency and intensity in DS (Mugica et al., 2002). This promted us to explore the true dimension of the problem and to stablish a series of norms designed to redress it. The aim of this study is to asses the effects of calcium an vitamin D3 supplementation on the bone metabolism in a group of ambulatory adults with DS using biochemical parameters related to phospho-calcium metabolism and bone remodeling.

Subjects and methods The study was carried out in San Sebastian, a city in northern Spain located at latitude 431N and with 1925 of sunlight. The group studied was formed by 23 persons with DS, whose characteristics are given in Table 1. All are residents in the Uliazpi Foundation. This Foundation is a public entity devoted to the study and care of persons with intellectual disability who require extensive and pervasive support. The selection criteria were acceptance by patients’ families, collaboration by patients themselves and compliance with the following requirements: feeding by mouth with no special diet, body mass index within a normal range, with absence of malnutrition signs, and the ability to walk in order to ensure adequate exposure to sunlight. Reasons for Table 1 Baseline values, expressed as mean (s.d.), by group

n Gender m/f Menses yes/no Age (years) Weigth (kg) Height (m) BMIa (kg/m2) BMD(g/cm2)b T Calcium (mmol/l) Phosphorous (mmol/l) Intact parathyroid hormone (pmol/l) 25 OH vitamin D3 (nmol/l) Osteocalcin (ug/l) Crosslaps (ug/l) a

Body mass index. Bone mineral density.

b

European Journal of Clinical Nutrition

Control group

Supplementation group

11

12

7/4 3/1 36.8 (8.1) 53.4 (9.8) 1.46 (0.1) 24.9 (3,3) 0.481 (0.1) 1.5 (0.9) 2.24 (0.12) 1.10 (0.16) 3.78 (1,27)

8/4 3/1 36.4 (9.7) 54.1 (13.9) 1.48 (0.1) 24.4 (4.4) 0.516 (0.1) 0.93 (0.8) 2.25 (0.05) 1.13 (0.19) 3.71 (1.35)

51.37 (24.5) 29.80 (6.7) 0.542 (0.2)

39.47 (18,25) 26.47 (17.6) 0.681 (0.3)

excluding patients from the sample group were as follows: having previously taken calcium or vitamin D3 supplements or medication for osteoporosis, the antiepileptic drugs phenobarbital, phenytoin or carbamazepine, fluoride supplements, oestrogen or testosterone, having a renal disease or having a history of urinary lithiasis. The possibility of celiac disease was discarded by checking that immunoglobulin levels were normal and that the patient did not have anti-endomisium antibodies. During the last ten years, three out of the 23 patients studied had suffered from bone fractures, and in all cases these fractures were caused by a traumatism. We designed a randomised, parallel, open and controlled clinical trial, and was carried out between June 2002 and June 2003. In all, 11 patients served as the control group and the remaining 12 received two daily tablets during the course of the year, each one containing 2.94 g of calcium lactogluconate, equivalent to 380 mg of elemental calcium, and 0.300 g of calcium carbonate, equivalent to 120 mg of elemental calcium, along with 400 IU of vitamin D3. The supplement was administered at breakfast time by carers. Randomization was performed by one of the authors using a list of permutations of six elements. The allocation list produced was concealed. The parameters analysed were BMD, biochemical tests related to the phospho-calcium metabolism (serum calcium, phosphorus, intact Parathyroid hormone and 25 OH vitamin D3) and biochemical markers of bone remodelling (serum osteocalcin, crosslaps). Giving the seasonal variation of serum vitamin D levels, they were repeatedly measured at baseline, 4, 8 and 12 months. BMD was measured on the distal phalanx of the middle finger as previously described by our study group (Mugica et al., 2002) and the results are expressed in absolute values (g/cm2) and standardized Tscores. Average values are taken from the EPISER study, carried out on the Spanish population using the same instrument (Ciria et al., 2001). The term osteopenia is applied to T values between 1 and 2.5, whereas the term osteoporosis is reserved for those cases in which T is equal or lower than 2.5. Blood samples were taken between 0800 and 1000 after 10 hours of fasting. Once the serum was separated, it was kept frozen a 401C until processed. The quantification of serum calcium and phosphorous was carried out using standard procedures in the Hitachi DDP modular platform (Roche Diagnostics). The reference values for adults are: 2.2– 2.7 mmol/l for calcium and 0.8–1.4 mmol/l for phosphorus. Serum Intact parathyroid hormone, crosslaps and osteocalcin were quantified by means of electro-chemoluminiscence, using the /EEES Elecsys platform (Roche Diagnostics). The intra-test and inter-test variation coefficients (CV) are 3.5 and 4.8% for intact Parathyroid hormone, 3.6 and 5.5% for crosslaps and 4.6 and 6.2% for osteocalcin. In all, 25 OH vitamin D3 levels were measured by radioimmunoassay, following extraction with acetonitrile (DIA SORIN Minnesota USA), the intra-test CV being 5.4% and the inter-test CV


607 8.5%. Bearing in mind recent recommendations regarding serum levels of this parameter (Go´mez Alonso et al., 2003b; Dawson-Hughes et al., 2005), values higher than 75 nmol/l are considered optimum, values of between 50 and 75 nmol/l compatible with D-hypovitaminosis, values of between 25 and 50 nmol/l insufficient and those lower than 25 nmol/l are considered to indicate clear deficiency of vitamin D3. Intact parathyroid hormone values of over 6.8 pmol/l are compatible with hyperparathyroidism. The study complied with the requirements of current Spanish law regarding clinical trials, was approved by the appropriate Clinical Research Ethics Committee, and by both the families and people responsible for the patients and the management team of the Uliazpi Foundation.

Statistical methods The results were recorded in the File Maker database and the statistical calculations carried out using the Winstat programme (both under Windows). The results of the descriptive statistical tests are expressed as mean (s.d.). Baseline and final values of every variable were compared within groups by means of a paired t-test. The difference (final minus baseline value) observed for every variable in the supplementation group was compared with that obtained in the control group using the t-test. A result was considered statistically significant when P was equal to or lower than 0.05. Furthermore, given the high biological variability offered by the osteocalcin and crosslaps markers, in order to assess the effectiveness of the treatment, the critical difference was taken into account, that is, the minimum clinically important change, that we established following Delmas’ recommendations (Delmas et al., 2000) in 30% for osteocalcin and 36% for crosslaps. There were no losses to follow-up in neither group, and every patient was analysed on an intention to treat analysis basis in the group to which he/she was randomized.

Results The study was carried out without any of the 23 participants being eliminated due to illness, failure to comply or any other reason. The supplement was well tolerated and its administration (in the form of effervescent tablets) generally accepted. No clinical (anorexia, vomits and constipation) or biochemical secondary effects (hypercalcemia) were noted that could be attributed to the supplementation. No significant differences were found between the control group and the supplementation group for any of the parameters at baseline (Table 1). Initial values of BMD measured on the side which gave the highest result showed that 52 and 9% suffered from osteopenia and osteoporosis respectively. Measurements taken on the side which gave the lowest result showed that 48% suffered from osteopenia and 22% from osteoporosis. Initial values of 25 OH vitamin D3 (summer) for the whole group were higher than 50 nmol/l, between 25 and 50 nmol/ and lower than 25 nmol/l in 21.7, 65.3 and 13% of cases respectively. The control group showed significantly lower average values of 25 OH vitamin D3 in winter (3rd determination) than in summer (1st and 4th determinations), 25.0711.2 as opposed to 49.5720.0 (Po0.01). This variation was not observed in the intervention group, which had increasing levels through the year, with a minimum value of 65 nmol/l, except in two cases in which the highest level obtained was 37.5 nmol/l. None of the initial values of intact Parathyroid hormone exceeded 6.8 pmol/l. Table 2 shows the results of the four determinations for each of the parameters studied along with the level of statistical significance of the differences between the initial and final values. No changes were observed in the serum levels of calcium and phosphorous, while the levels of intact Parathyroid hormone, osteocalcin and crosslaps were lower. The decrease was gradual for the latter three parameters in the supplementation group.

Table 2 Evolution of values, expressed as mean (s.d.), by group. Significance tests compare final and baseline values within each group Baseline

4 months

8 months

12 months

P

Calcium (mmol/l)

Control group Supplementation group

2.24 (0.1) 2.25 (0.1)

2.30 (0.1) 2.30 (0.1)

2.29 (0.1) 2.33 (0.1)

2.28 (0.1) 2.36 (0.1)

NS NS

Phosphorous (mmol/l)


1.09 (0.2) 1.13 (0.2)

1.12 (0.2) 1.10 (0.1)

1.20 (0.1) 1.13 (0.1)

1.23 (0.2) 1.17 (0.2)

0.04 NS

Intact Parathyroid hormone (pmol/l)


3.78 (1.3) 3.71 (1.3)

2.91 (1.1) 3.02 (2.4)

4.05 (1.3) 2.41 (1.4)

3.65 (1.1) 2.17 (0.8)

NS 0.0004

25 OH vitamin D3 (nmol/l)


51.37 (24.5) 39.47 (18.2)

51.50 (20.7) 61.22 (26.2)

72.75 (13.0) 68,47 (26.5)

57.50 (1.5) 75.78 (25.2)

NS 0.0003

Osteocalcin (ug/l)


29.80 (6.7) 26.47 (17.6)

26.13 (4.6) 26.47 (10.7)

27.22 (10.5) 23.84 (12.6)

30.79 (9.4) 22.58 (10.5)

NS 0.001

Crosslaps (ug/l)


0.542 (0.2) 0.681 (0.3)

0.433 (0.1) 0.346 (0.1)

0.405 (0.1) 0.320 (0.1)

0.474 (0.2) 0.360 (0.2)

NS 0.001



608 Table 3 Difference between final and baseline values by groups, expressed as mean (s.d.)

Calcium(mmol/l) Phosphorous (mmol/l) Intact Parathyroid hormone (pmol(l) 25 OH vitamin D3 (nmol/l) Osteocalcin (ug/l) Crosslaps (ug/l)

Control group

Supplementation group

P

0.04 (0.1) 0.13 (0.2) 0.13 (1.2)

0.11 (0.1) 0.04 (0.2) 1.49 (1.1)

NS NS 0.007

6.10 (16.5) 0.98 (6.9) 0.01 (0.21)

36.25 (24.5) 14.22 (11.8) 0.32 (0.3)

0.002 0.001 0.02

The increase or decrease (final minus baseline value) in the serum levels of the variables studied were compared between groups, as shown in Table 3. Vitamin D increased while crosslaps, osteocalcin and intact Parathyroid hormone decreased significantly in the supplementation group, translating a beneficial effect of the intervention. As specified above, if a decrease of over 36% is considered clinically important as a cut off value for crosslaps, then the number of cases that fulfil this condition is 9% of the control group and 66.6% of the intervention group. For osteocalcin, 9% in the control group and 75% in the treated group showed decreases of al least 30%.

Discussion In assessing the effect of Ca and vitamin D treatment we have used biochemical parameters related to phosphocalcium metabolism and bone remodelling markers. Our main interest focused on analysing changes in bone remodelling markers, osteocalcin and crosslaps, since both are considered useful, as they reflect significant bone turnover changes after a treatment (La-or et al., 2001; Okabe et al., 2001; Gannage-Yared et al., 2003). We did not assess the BMD at the end of the study as the subject numbers are too low to detect significant differences and the technique used in the study is useful for screening purposes but not for assessment of treatment effect (Lewiecki et al, 2004). The assessment in serum of 25 OH vitamin D3 seems to clearly reflect the vitamin D status (Zerwekh, 2004), although there is no clear consensus about which are its more adequate levels both in healthy population and in groups with the risk of developing metabolic bone disease. Levels between 50 and 80 nmol/l are considered optimum for reducing fracture risks (Dawson-Hughes et al., 2005). In order to assess the initial vitamin D status in the global DS group, we have not compared our results with a control group, but used deficiency and insufficiency criteria most in keeping with the real situation. Selected cut-off values obtained from population studies, some of which are in our geographical area (Go´mez Alonso et al., 2003b), are mainly based on the reverse relationship between 25 OH vitamin D3 levels and European Journal of Clinical Nutrition

intact parathyroid hormone, the first being an independent hyperparathyroidism predictor (Chapuy et al., 2002; Go´mez Alonso et al., 2003a; Vieth et al., 2003; Lips, 2004). In contrast to the data obtained by Del Arco et al. (1992) in children with DS, in our study almost 80% of the group (n ¼ 23) had deficiency or insufficiency of vitamin D3 during the summer, according to the aforementioned criteria, although no instances of secondary hyperparathyroidism (intact parathyroid hormone 46.8 pmol/l) were observed. All members of the treated group reached levels of over 65 nmol/l, except for two patients who only obtained levels of 37.5 nmol/l. This means that a treatment of 800 U/day of vitamin D3 ensures serum levels of 25 OH vitamin D3 that are very close to the recommended levels and that result in a significant drop in the values of intact parathyroid hormone. The patients whose 25 OH vitamin D3 levels failed to increase were both males, aged 36.2 and 37.8. The first regularly takes Allopurinol, for which we found no recorded cases of interference with vitamin D3, and the second receives valproic acid as a regular treatment. The effect of antiepileptic drugs on the skeletal system by means of interference in the vitamin D3 metabolism is widely accepted in the case of phenobarbital and widely debated in the cases of phenytoin and carbamazepine. This interference has not been proven in the case of valproic acid (Gough et al, 1986). which is why it was not included on the list of excluded medications. As expected, after the treatment a decrease in bone remodelling markers was observed, being differences between treated groups and placebo groups quite significant. Besides, when handling these parameters, change percentage values associated to values are generally used in order to determine the effectiveness of a treatment. We have chosen cut-off values suggested in the recommendations on the use of biological indexes in order to monitor osteoporosis treated with other more powerful antiresortive agents (HRT; alendronate) through which a BMD response above a 3% for a 90% specificity is foreseen. We consider the fact that in 76% of the patients a decrease higher than the specified cut off values was detected to be extremely significant and these acute changes could be clinically relevant in order to predict a long-term positive effect in BMD, as it is in the line of study of Grados et al (Grados et al, 2003). The changes observed in our study are compatible with a deficiency or insufficiency of vitamin D3 or calcium, or both together. This deficiency has been demonstrated in elderly people and has been attributed to a defect in intestinal absortion (Bullamore et al., 1970) and to a decrease in the production of vitamin D3 by the skin (MacLaughlin and Jolick, 1985). That this deficiency is not specific to elderly people has been shown in recent studies (Tangpricha et al., 2002; Gordon et al., 2004), nevertheless, we think that vitamin D deficit is more pronounced in the study group and could be interpreted as yet another manifestation of DS patient’s different rhythm of maturing and ageing in comparison with the general population.


609 The results presented demonstrate the need to research an aspect of the tests and healthcare of adult DS patients which has not yet been sufficiently explored. The biochemical changes observed may not be considered sufficient to recommend the systematic administration of calcium and vitamin D3 supplements in such patients, but they do indicate the need for collaborative studies to determine whether or not there is in fact a higher frequency of fractures or other problems attributable to osteoporosis and whether this can be prevented by the early administration of Ca and vitamin D3 supplements.

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