Serum Calcidiol Research Articles

Low serum calcidiol concentration in older adults with reduced muscular function.

To examine the association between muscular function and the serum concentrations of 25-hydroxyvitamin D (calcidiol) and 1,25-dihydroxyvitamin D (calcitriol). A randomized population survey. Baseline measurements of serum calcidiol and calcitriol concentrations and assessment of muscular function (hand grip strength, ability to climb stairs, outdoor activity, and fall occurrence). The Medical department, Aker University Hospital, Oslo, and subjects' homes. Two hundred forty-six recently hospitalized older patients and 103 randomly selected older people living at home. Serum concentration of calcidiol and calcitriol in relation to muscle function. Reduced muscle function was associated with low calcidiol levels. In both the hospital group and the home group, calcidiol concentrations correlated positively to arm muscle strength (r = .22, P < .001; r = .37, P < .001), ability to climb stairs (r = -.16, P < .05; r = -.42, P = < .001), physical activity (r = -.27, P < .001; r = -.31, P < .001), and the absence of fall occurrences (r = -.27, P < .001; r = -.31, P = .004). Calcitriol showed an association with physical activity in the hospital group (r = -.19, P < .05), and with fall last month in the home group (r = -.22, P < .05). Older people with reduced muscle function often had reduced levels of calcidiol serum concentration. Low levels of calcidiol were not associated with signs of general undernutrition, such as low body mass, or with reduced arm-muscle circumference or triceps skinfold thickness. This finding may suggest a physiological role for calcidiol in muscle function. Reduced muscle strength increased disability in our older subjects, which may be improved by vitamin D supplementation in vitamin D-deficient subjects.

Dietary calcium and vitamin D intake in elderly women: effect on serum parathyroid hormone and vitamin D metabolites

In this study, the effect of dietary calcium and vitamin D on serum parathyroid hormone and vitamin D metabolites was measured in 376 free-living women aged 65-77 y. Mean calcium intake in both groups was close to the recommended dietary allowance of 800 mg/d. Mean vitamin D intake in the 245 women not taking vitamin D supplements was 3.53 microg/d (141 IU/d), which is below the recommended dietary allowance of 5 microg/d (200 IU/d). To test the hypothesis that vitamin D is more important than calcium in reducing serum parathyroid hormone, the source of dietary calcium intake was subdivided into milk, which is fortified with vitamin D, and nonmilk sources. The serum parathyroid hormone concentration was inversely correlated with calcium intake derived from milk (r = -0.20, P < 0.01) but not from nonmilk sources (r = -0.06). Furthermore, serum calcidiol correlated with milk calcium intake (r = 0.35, P < 0.001) but not with nonmilk calcium intake (r = 0.10). Multivariate analysis showed a significant effect of season on serum calcidiol but not on serum parathyroid hormone. Serum parathyroid hormone was inversely correlated with serum calcidiol (r = -0.33, P < 0.001) and the regression predicted that mean serum parathyroid hormone would be reduced in the elderly to concentrations considered normal in the young when serum calcidiol is 122 nmol/L (49 ng/mL); this would require a much higher recommended dietary allowance for vitamin D than 5 microg/d (200 IU/d).

Vitamin D, calcium, and bone status in children with developmental delay in relation to anticonvulsant use and ambulatory status

Reports of abnormalities in vitamin D, calcium, and bone status associated with anticonvulsant use are inconsistent and difficult to interpret because of widely varying study designs, particularly for ambulatory status. We examined the relative effects of anticonvulsant use and ambulatory status on vitamin D, calcium, and bone status in a large group (n = 338) of children who had either normal motor function (ambulatory) or were nonambulatory and either receiving anticonvulsants or not; all had developmental delays. Data included diet records, serum analyses (calcium and calcidiol), and hand-wrist radiographs evaluated for bone maturation and quality. Data were analyzed by using a general linear models (GLM) procedure. Dietary and biochemical data were compared with those of a group of 34 normal children. There were no differences in calcium or vitamin D intakes among the four study groups; however, a high percentage of intakes was below the recommended dietary allowances for calcium (56%) and vitamin D (70%). Vitamin D intakes were positively associated with serum calcium (P < 0.005) and calcidiol (P < 0.01) concentrations. Analysis of covariance indicated that ambulatory status but neither anticonvulsant use nor their interaction contributed significantly to the prediction of serum calcium (P < 0.009) and calcidiol (P < 0.0001), the Z scores for number of ossified centers (P < 0.008), bone age (P < 0.0001), and bone area (P < 0.003). A strong interaction between anticonvulsant use and ambulatory status was seen for percentage cortical area (P < 0.0008), which was entirely due to anticonvulsant use in nonambulatory children (effect size = 0.98). Results suggest that ambulatory status is more important than was recognized previously in relation to abnormalities in vitamin D, calcium, and bone statuses; that all nonambulatory children may be at risk for low serum calcidiol and osteopenia; and that routine monitoring of risk and consideration of prophylactic vitamin D supplementation are warranted.

Serum vitamin D metabolites and calcium absorption in normal young and elderly free-living women and in women living in nursing homes

Vitamin D deficiency, which causes osteomalacia, may also be important in the pathogenesis of age-related osteoporosis. We studied serum vitamin D metabolites in 52 young women (mean age: 30 +/- 3 y; range: 25-35 y), 64 elderly free-living women (mean age: 71 +/- 4 y; range: 65-82 y), and 60 elderly women living in nursing homes (mean age: 84 +/- 9 y; range: 61-102 y). Mean serum 25-hydroxyvitamin D (calcidiol) was 10.8 +/- 4.4 nmol/L (27 +/- 11 ng/mL) in women living in nursing homes and was similar to that of free-living young (11.3 +/- 4.2 nmol/L, or 28 +/- 10 ng/mL) and elderly (11.5 +/- 3.2 nmol/L, or 29 +/- 8 ng/mL) women. Vitamin D deficiency (defined as serum calcidiol < 4.8 nmol/L, or 12 ng/mL) occurred in 8% of women living in nursing homes, in 6% of the young women, and in 1.6% of the free-living elderly women. Serum calcidiol was significantly correlated with vitamin D intake (r = 0.25, P < 0.05) and inversely correlated with serum intact parathyroid hormone (iPTH) (r = -0.16, P < 0.03). Serum iPTH increased with age and secondary hyperparathyroidism was observed in 17% of the women living in nursing homes. Calcium absorption declined with age, but calcium absorption and serum 1 alpha,25-dihydroxyvitamin D (calcitriol) were significantly lower in women living in nursing homes, which probably contributed to the secondary hyperparathyroidism. In conclusion, normal serum calcidiol may avoid the problem of osteomalacia, but it does not correct malabsorption of calcium. Although calcitriol corrects the malabsorption of calcium, it remains to be seen whether higher amounts of vitamin D can normalize the calcium malabsorption of aging.

Subclinical vitamin D deficiency in neonates: definition and response to vitamin D supplements

To determine the biological criteria for neonatal vitamin D deficiency, serum 25-hydroxyvitamin D (calcidiol), parathyroid hormone (PTH), calcium, phosphates, and alkaline phosphatase (ALP) activity were measured during the winter-spring period in 80 healthy neonates and their mothers 3-6 d after delivery. A longitudinal 3-mo survey of the serum biology of 52 of these neonates consuming formula was also performed to test the influence of their neonatal vitamin D status on the effects of two oral ergocalciferol supplements (500 and 1000 IU or 12.5 and 25 micrograms/d). At birth, 63.7% of the infants had calcidiol concentrations < or = 30 nmol/L. Most of them had no other biological sign evocative of vitamin D deficiency, but 14 neonates had low calcidiol concentrations and serum PTH concentrations > 60 ng/L, the upper limit of the adult normal range. They also had a significantly lower mean serum calcium concentration than did neonates with calcidiol concentrations > 30 nmol/L. On the basis of the association of low calcidiol concentrations (< or = 30 nmol/L) and high PTH concentrations (> 60 ng/L) as criteria for vitamin D deficiency, 24% of the neonates born to unsupplemented mothers were found to be vitamin D-deficient. Neonatal vitamin D status influenced the response of the infants to vitamin D supplements. Neonates with no sign of vitamin D deficiency showed similar changes in their serum calcidiol, calcium, phosphate, and PTH concentrations and ALP activity and no toxic effect (hypercalcemia or highly elevated calcidiol concentration) was observed whatever their vitamin D intake. In contrast, neonates with subclinical vitamin D deficiency had normalized serum PTH within 1 mo only when they were given 1000 IU ergocalciferol (25 micrograms)/d in addition to their formula.

Relationship between baseline insulin-like growth factor-I (IGF-I) and femoral bone density in women aged over 70 years: potential implications for the prevention of age-related bone loss.

To test the hypothesis that the decline in femoral bone mass associated with healthy aging is partially accounted for by deficiency of the growth hormone-insulin-like growth factor-I (IGF-I) axis. Cross-sectional study. A sample of 245 community-dwelling healthy women aged 70 and older. Exclusion criteria were diseases or medications known to affect the musculoskeletal system or the somatotrophic axis. Serum levels of IGF-I, calcitriol, and osteocalcin were determined by radioimmunoassay; serum calcidiol was measured by competitive binding assay, and serum parathyroid hormone (PTH) was assessed immunochemically. Urinary pyridinium crosslinks were measured by fluorescent detection after high-pressure liquid chromatography. Isometric and isokinetic quadriceps strength was evaluated using an isokinetic dynamometer. Bone density (BMD) was assessed by dual-energy X-ray absorptiometry at the proximal femur. Multiple regression was used to adjust for potential confounders. At the proximal femur, BMD declined by 0.59-0.84% per year. In addition to body mass index and muscle strength, serum IGF-I was found to be an independent predictor of BMD at all femoral sites. The data support the hypothesis that circulating IGF-I not only reflects the integrated growth hormone secretion but also has a direct role in the endocrine regulation of bone remodeling. The present findings support the need for further studies to assess the potential of IGF-I in attenuating age-related femoral bone loss.

Serum calcidiol and calcitriol concentrations in elderly people: variations with age, sex, season and disease

The influence of age, sex, seasonal variations and vitamin D supplementation on serum concentrations (s-conc.) of calcidiol and calcitriol were studied in 311 hospitalized and 106 home-living people aged 70 years and over, residing at 60° latitude. The serum calcidiol conc. (meanSD, nmol/L) was reduced in the hospital group compared to the home-living group (males: 40.6 ± 23.2 compared to 59.6 ± 28.9; females: 37.3 ± 22.6 compared to 48.5 ± 20.3) and showed no seasonal variation. The homeliving group showed highest levels in August-September (62.2 ± 26), and lowest levels in January–March (42.9 ± 21). Serum calcidiol declined with age, most prominent in the home group (males: r = −0.13, P = 0.036;females: r = −0.33, P = 0.001). A positive correlation was shown between s-calcitriol and s-calcidiol conc. ( r = 0.26, P > 0.001). An increased s-conc. of calcidol was present in those with vitamin supplementation (home: 59.9 ± 26; hospital: 43.4 ± 22) compared to those without supplementation (home: 46.6 ± 22; hospital: 36.2 ± 22), but s-calcidiol conc. did not correlate to nutritional vitamin D intake. Vitamin D deficiency (s-calcidiol conc. < 30 nmol/L) was more common in old people recently admitted to hospital, compared to those living at home. Only the home-living group had the benefit of sunlight exposure, but both groups may benefit from vitamin supplementation.

Remission of hypercalciuria in patients with tuberculosis after treatment.

The hypercalciuria evolution and other bone metabolism parameters were evaluated in patients with tuberculosis after treatment. Twenty-two patients with tuberculosis and 54 normal subjects were studied; they consumed an average diet (calcium intake 1000 mg/day). Ten of these patients and nine normal subjects were also studied after a low calcium diet (400 mg/calcium/day) and after a load of oral calcium of 1000 mg (calcium absorption test). The study with an average diet was performed after 1 week (basal) and 3, 6, and 12 months after the antituberculosis treatment was started; the calcium absorption test was carried out 2 weeks, 3 and 12 months after the treatment was started. On an average diet, patients with tuberculosis presented, at baseline state, lower calcidiol levels than normal controls. Serum calcitriol levels at baseline were higher than at 6 and 12 months. Serum parathyroid hormone (PTH) levels in patients with tuberculosis were lower than in normal controls at baseline, but these levels were similar to controls at 3, 6, and 12 months after treatment. During the calcium absorption test and under basal conditions, patients with tuberculosis showed lower serum PTH and calcidiol levels in all the dietetic situations than in normal controls. However, serum calcitriol levels were higher than in controls after the restrictive diet. After 3 months of treatment, urinary calcium excretion was normal in patients with tuberculosis during the average and low diets, but higher than in control group after calcium load. After 12 months of treatment, all the biochemical parameters of the patients with tuberculosis were similar to the control group under all the dietetic situations. These data indicate that antituberculous treatment, although it may contribute to the production of some alteration in the calcium and vitamin D metabolism, basically favors the correction of disturbances associated with tuberculosis.

Effect of Oral Calcidiol Treatment on Its Serum Levels and Peritoneal Losses

To evaluate calcidiol serum levels in a group of continuous ambulatory peritoneal dialysis (CAPD) patients and the effect of oral calcidiol treatment on serum levels and peritoneal losses. Twenty patients (13 female, 7 male) were studied for 12-60 months. Their ages ranged 22-72 years (mean 46 +/- 15). Serum calcidiol, total protein and urea were determined at baseline and after the administration per os of 0.133 mcg/day of calcidiol for 10 days. At the same time, calcidiol and total protein were measured in peritoneal effluent at baseline and at 5, 10, and 40 days after starting this treatment. A significant and direct correlation between the calcidiol dialysis/plasma ratio and the peritoneal protein losses was found, both before and 40 days after calcidiol administration when calcidiol serum levels were the lowest. As calcidiol serum levels rose to the normal range in the course of the study, peritoneal losses of this metabolite increased slightly and correlated with calcidiol serum levels and urea mass transfer coefficient (MTC); the significant correlation between calcidiol serum levels and peritoneal protein losses disappeared. When serum calcidiol levels are low, calcidiol peritoneal losses in patients on CAPD correlate with protein peritoneal losses. However, when serum calcidiol levels rise, the calcidiol peritoneal losses correlate with calcidiol serum levels and urea MTC, and not with protein peritoneal losses.

Relations between calcidiol serum levels and bone mineral density in postmenopausal women with low bone density

The relationship between vitamin D and bone density was studied in 150 selected, mature (45-74), postmenopausal women with a lumbar spine Z score below 0. Vitamin D status was evaluated using calcidiol serum levels. Serum calcitriol and parathyroid hormone (PTH) values were also evaluated in some subjects. Bone mass was evaluated by ascertaining bone density and Z and T scores in the lumbar spine and femur region. The reference group consisted of 25 premenopausal women. The postmenopausal group was divided into subgroups according to age, i.e., under or over 60 years old. Additionally, the whole group was also subdivided according to their lumbar spine Z scores into group I (Z > -1), group II (Z < -1; > -2), and group III (Z < -2). Group III of postmenopausal women had higher PTH and lower calcitriol levels than premenopausal women. Calcidiol serum levels were lower in postmenopausal women groups II or III than in the group I and premenopausal women. Calcidiol serum levels and the bone mass values for the lumbar spine were correlated positively in all the postmenopausal women; in the women over 60 years of age, calcidiol levels also correlated with the bone mass values expressed as the bone density in three femur regions: femoral neck, trocanter, and Ward's triangle. In conclusion, mature post-menopausal woman showed high PTH levels and low calcidiol and calcitriol values. Calcidiol status is significantly related to bone mineral density in the lumbar spine and in women over 60 years, calcidiol levels also correlated with bone density in the femur regions.

Reference data for bone mass, calciotropic hormones, and biochemical markers of bone remodeling in older (55-75) postmenopausal white and black women

From a random sample of our institution's health maintenance organization (HMO), we recruited 250 white women and 112 black women, aged 55-75, all of whom were 10 or more years postmenospause with minimal estrogen exposure and free of osteoporosis, other metabolic bone disease, and medical, surgical, or therapeutic situations that may influence bone loss. Bone mass was measured in the radius, spine, and femur by DXA and in L1 by QCT. Serum samples were analyzed for parathyroid hormone, calcidiol, calcitriol, osteocalcin, and bone alkaline phosphatase and urine samples analyzed for creatinine, calcium, and hydroxyproline. Mean Z score, based on published reference data for forearm and femoral neck BMD in the white women, was not significantly different from zero, but mean Z score at the lumbar spine was 0.6 (p < 0.001), 17.2% of the individual values being > 2.0. In normal white women (BMI < 27.3, n = 143), Z score was still > 2.0 in 10.3%, suggesting that the upper bound of the published reference interval may be too low. After adjustment for body mass index, BMD was greater in the forearm (9.8%), spine (8.7%), and femoral neck (14.7%) in black women (p < 0.001 at all sites). At L1, adjusted BMC in the black women was 37.4% greater than in the white women (p < 0.001). Serum calcidiol was significantly lower and serum PTH and calcitriol significantly higher in the black women. Despite this, biochemical markers of bone resorption and formation were significantly lower in the black women. We conclude that skeletally healthy older black women have a greater bone mass and lower rates of bone remodeling than a comparable group of white women. These data can serve as reference intervals for the variables measured.

Acute effects of intravenous 1α-hydroxycholecalciferol on parathyroid hormone, osteocalcin and calcitriol in man

The acute effects of a single intravenous injection of 2 micrograms of 1 alpha-hydroxycholecalciferol (alfacalcidol) were studied for a 24-h period in six normal males (mean age 33 years), six women with primary hyperparathyroidism (mean age 72 years) and six women with established osteoporosis (mean age 63 years). In all three groups, serum calcitriol levels rose to a peak 2-3 h after administration of alfacalcidol. Basal levels were highest in the primary hyperparathyroidism group at (mean +/- SEM) 81 +/- 2 vs 62 +/- 12 (normal males) (p < 0.05) and 56 +/- 5 pmol/l (osteoporosis) (p < 0.01). Highest peak levels were found also in the primary hyperparathyroidism group at 150 +/- 15 vs 114 +/- 15 (normal males) (p < 0.05) and 127 +/- 15 pmol/l (osteoporosis) (p < 0.01). The rise in calcitriol was higher in the primary hyperparathyroidism group than either the normal males or osteoporotic patients (p < 0.05). No significant differences were evident in basal serum calcidiol concentrations among the three treatment groups. As might be expected, highest basal concentrations of parathyroid hormone (PTH), serum calcium and serum osteocalcin were noted in the primary hyperparathyroid group (PTH: 17.1 +/- 7.7 vs 1.9 +/- 0.5 (normal males) (p < 0.01) and 2.1 +/- 0.3 pmol/l (osteoporosis) (p < 0.01); calcium: 3.06 +/- 0.08 vs 2.50 +/- 0.02 (normal males) (p < 0.01) and 2.43 +/- 0.02 mmol/l (osteoporosis) (p < 0.01); osteocalcin: 1.10 +/- 0.08 vs 0.56 +/- 0.16 (normal males) (p < 0.05) and 0.53 +/- 0.21 nmol/l (osteoporosis) (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

In Reply

We appreciate Dr. Feiner's concern with the methodological details of our study.1 We agree that our sampling method was less than optimal for purposes of generating the descriptive (univariate) statistics included in our report. As we pointed out, we were constrained by ethical considerations from incorporating a purely random sample of individuals from the two institutions involved. However, we do not agree that relying on individuals who are scheduled for a routine physical examination is necessarily an ideal alternative. As we mentioned, our primary sample did in fact consist of residents who were due for phlebotomy in conjunction with their annual physical examination during the time frame of the study. We found that cognitively impaired individuals, in particular, were commonly having these routine blood chemistries canceled because of recent phlebotomy for non-routine reasons, and they were, therefore, underrepresented in this group as well as the secondary sampling group by comparison with a simple random sample. Thus, our study was necessarily biased toward including mentally alert individuals, regardless of the sampling method used. We were careful to take both mental status and sampling method into account in our multivariable analyses, however, and, as we also pointed out, the choice of sampling subgroup had no effect on our analytic findings. It is important to note that, while we did see a tendency toward lower serum calcitriol levels in cognitively impaired individuals, we found no evidence that this was mediated by diminished levels of substrate (calcidiol), and, therefore, insufficient sunlight exposure, or diminished calciferol (vitamin D) intake. With respect to the measurement issues raised by Dr. Feiner, we agree that it is important to use a consistent method of measurement whenever possible. The measurement of vitamin D metabolite levels was in fact carried out in a single laboratory. The use of two methods of dietary measurement was made necessary by the substantially different eating practices of mentally alert and cognitively impaired individuals. A dietary recall approach was used with alert individuals since they had access to cafeterias and more sporadic eating patterns than cognitively impaired individuals. Both methods yielded measurements of vitamin D intake which correlated well with the biochemical measurement of serum calcidiol, which has not always been the case in previous studies.2,3 In passing, it should be noted that one cannot rely on computer software alone to compute the calciferol content of individual meals, as suggested by Dr. Feiner, since fortification practices for processed foods other than milk vary over time and from one commercial source to another.

Exogenous Calciferol (Vitamin D) and Vitamin D Endocrine Status among Elderly Nursing Home Residents in the New York City Area

To determine the role and relative importance of sources of exogenous calciferol (vitamin D) in maintaining vitamin D endocrine status in the mid-winter and early spring in a representative sample of institutionalized elderly persons in the New York City area. Cross-sectional survey. A privately-run urban nursing home and the long-term care unit of a suburban public hospital. Residents aged 60 years and older scheduled for a routine annual physical examination and an additional group of individuals ascertained by random sampling. Those with a history of anti-convulsant or glucocorticoid use, liver disease, chronic renal disease (or serum creatinine > 1.5 mg/dL), parathyroid disease, Paget's disease, gastric surgery, or pharmacological vitamin D use were excluded. Of 301 sampled individuals, 221 were found eligible to participate, and 109 were successfully enrolled. The average vitamin D intake was 379 IU/day (range 55-1006 IU/day) and total vitamin D intake was below the Recommended Dietary Allowance in 16% of subjects. Fifty percent of total vitamin D intake came from fortified milk, and 26% came from vitamin supplements. Vitamin supplement use was not associated with low dietary intake. Among subjects taking a supplement containing 400 IU/day, none had serum calcidiol levels below 15 ng/mL, while among subjects with vitamin D intake between 200 and 400 IU/day, 46% had serum calcidiol levels below 15 ng/mL and 14% had calcidiol levels below 10 ng/mL. Vitamin D intake from non-supplement sources (but not from supplements) appeared to have a negative association with serum calcitriol levels. Many nursing home residents may require vitamin supplements in order to achieve optimal levels of calciferol replacement. The choice of a vehicle for calciferol replacement may affect calcitriol levels.

The Necessity and Safety of Calcium and Vitamin D in the Elderly

The necessity and safety of an oral calcium (Ca) and vitamin D regimen was evaluated in a population of 66 independently living and 73 institutionalized elderly women over an 11-week winter period. The members of both groups were randomly assigned into trial and control groups. Serum Ca, creatinine, and calcidiol levels were measured before and after the trial. The regimen consisted of 1.558 g of Ca and 45 micrograms (equal to 1,800 IU) of vitamin D administered daily in addition to the normal diet. The controls received no treatment. A majority of the elderly subjects living independently had ensured their Ca, and a quarter of them also their vitamin D intake on their own initiative. The mean serum calcidiol concentration before the trial was 24.1 nmol/L in the institutionalized and 38.5 nmol/L in the elderly subjects living independently (P less than .001). After the trial, serum calcidiol was 10.4 nmol/L in the institutionalized control subjects and had decreased (P less than .001) in both control groups, but increased (P less than .001) in both treatment groups. The safety indicators, serum Ca, creatinine, and calcidiol, did not indicate any group or individual side effect.

Bone and Mineral Metabolism and Chronic Alcohol Abuse

Studies of bone and mineral metabolism were made in 22 patients with chronic alcohol abuse and varying degrees of liver damage. None of the patients had clinical evidence of metabolic bone disease, but quantitative bone histology showed that six had osteoporosis, three osteomalacia, and two osteoporosis and osteomalacia combined. Trabecular bone volume (TBV) tended to be reduced in relation to age, and there was histological evidence of reduced bone formation particularly among the patients with osteoporosis. Multivariate analysis of the relevant variables showed that the major determinants of age-adjusted trabecular bone volume were the serum concentration of albumin and the dietary calcium. The presence of osteoporosis was related to the state of liver function and the type of alcohol habitually consumed, and was a particular feature of patients with severe liver disease and those who only drank spirits. Six patients (five with osteoporosis) had biochemical evidence of hyperparathyroidism, but none showed histological evidence of increased bone resorption or of osteitis fibrosa. In four patients the development of hyperparathyroidism was probably related to underlying magnesium deficiency. Serum calcidiol tended to be reduced and was directly related to the state of liver function; four patients had reduced or low normal serum concentrations of calcitriol. In only three patients could the development of osteomalacia be related to vitamin D deficiency; in two patients the cause of the osteomalacia was obscure. Significant changes in bone structure and mass appear to be common among heavy drinkers even in the absence of clinical metabolic bone disease. These skeletal abnormalities are likely to be relevant to the increased fracture risk associated with heavy drinking.

Circulating vitamin D metabolite concentrations in children with nutritional rickets

Serum calcidiol, calcitriol, and 24,25-dihydroxyvitamin D concentrations were measured in 20 children with vitamin D-deficiency rickets. Vitamin D metabolite concentrations were measured in 17 of 20 patients before treatment and in 14 of 20 patients after vitamin D administration. Conclusions are as follows. (1) Before treatment, serum calcidiol seems to be the best criterion of D deficiency, as it was low (less than 8 ng/ml) in 15 of 17 studied children, whereas calcitriol and 24,25-dihydroxyvitamin D concentrations ranged from undetectable to high values (350 pg/ml and 5.9 ng/ml, respectively). (2) Low calcidiol concentrations may occur despite recent vitamin D intake: low serum values were found in children given vitamin D2 up to two months after the onset of therapy (50 micrograms/day). (3) Elevated calcitriol serum concentrations were observed in all children after initiation of vitamin D therapy; these high concentrations persisted for four weeks or more, even after normalization of serum calcium, phosphorus, and parathyroid hormone values. (4) Healing of biochemical abnormalities can occur even in children with low circulating concentrations of calcidiol and 24,25-dihydroxyvitamin D.