24-25-dihydroxyvitamin-d-3 and 25-26-dihydroxycholecalciferol

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Biological Transport; Bone and Bones; Bone Resorption; Calcifediol; Calcitonin; Calcitriol; Calcium; Calcium-Binding Proteins; Cartilage; Chemical Phenomena; Chemistry; Cholecalciferol; Dihydroxycholecalciferols; Female; Humans; Hydroxycholecalciferols; Intestinal Absorption; Intestines; Kidney; Liver; Minerals; Parathyroid Hormone; Phosphorus; Pregnancy; Skin; Steroid Hydroxylases; Ultraviolet Rays; Vitamin D; Vitamin D-Binding Protein

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Animals; Biological Assay; Calcitriol; Chromatography, Gas; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Protein Binding; Spectrophotometry, Ultraviolet; Vitamin D

Vitamin D metabolism was studied in the 'Hannover Pig', a strain which suffers from pseudo vitamin D-deficiency rickets, type I. Animals of this strain are known to be devoid of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase and -24-hydroxylase activities. Pigs with florid rickets and hypocalcaemia were treated with single im injections of 0.25 to 1.25 mg of vitamin D3, doses that have been shown in previous studies to be effective in producing transient healing of rachitic symptoms. The levels of vitamin D3 and its most relevant physiological metabolites in plasma were estimated at intervals before and after this vitamin D3 treatment. Vitamin D3 rose from 14.8 +/- 8.1 to 364 +/- 190 nmol/l (mean +/- SD) 2 to 3 days post injectionem, 25-hydroxyvitamin D3 from 131.0 +/- 46.2 to 1068 +/- 160 nmol/l within 7 days post injectionem. The 1 alpha, 25-dihydroxyvitamin D3 concentration in plasma was elevated from 73.9 +/- 25.0 to 281 +/- 168 pmol/l 2 to 3 days post injectionem and declined continually from that time. 24R,25-dihydroxyvitamin D3 and 25S,26-dihydroxyvitamin D3 levels after treatment showed different responses in different animals being either elevated or unchanged. Clinical healing of the pigs with these doses of vitamin D3 was attributed to the transient rise of 1 alpha,25-dihydroxyvitamin D3 in plasma. It was assumed that 1 alpha,25-dihydroxyvitamin D3 synthesis takes place under these circumstances in extrarenal tissues.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Calcium; Cholecalciferol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Radioimmunoassay; Rickets; Swine

By use of a single-cartridge system, 1,25-dihydroxyvitamin D [1,25(OH)2D] is extracted and purified from a plasma or serum sample. Proteins are removed and 1,25(OH)2D is liberated from the sample with acetonitrile. The acetonitrile extract is applied to the nonpolar octadecylsilanol silica cartridge, in which 1,25(OH)2D is retained while polar compounds are eluted. Then by "phase-switching" on the same cartridge, 1,25(OH)2D is sufficiently resolved from other vitamin D metabolites and extraneous lipophilic compounds to allow its quantification by radioreceptor assay according to an established procedure. Mean (and SD) values for 1,25(OH)2D in serum of 29 normal, 27 chronic renal failure, and nine pregnant subjects were 28.2 (11.3), 10.9 (5.2), and 47.3 (12.9) ng/L, respectively. Results compared well with those of an established radioreceptor procedure. This procedure offers the advantage of a single rapid purification step not involving "high-performance" liquid chromatography or evaporation, under nitrogen, of polar solvents such as acetonitrile or methanol.

Topics: 24,25-Dihydroxyvitamin D 3; Calcitriol; Cholecalciferol; Dihydroxycholecalciferols; Female; Humans; Kidney Diseases; Labor, Obstetric; Pregnancy; Radioligand Assay; Specimen Handling

Serum concentrations of vitamin D metabolites were measured before and during treatment with either vitamin D2 or vitamin D3, 4000 IU per day for 24 weeks, in 22 epileptic outpatients receiving phenobarbitone/phenytoin. The serum concentration of total 1,25(OH)2D did not change during the treatment period in any of the treatment groups. On the other hand, in the vitamin D2 group, serum 25(OH)D2, total 25(OH)D, and 24,25(OH)2D increased significantly during the trial, whereas serum concentrations of the vitamin D3 metabolites were unchanged. In the vitamin D3 group, serum concentrations of the vitamin D3 metabolites increased significantly, whereas the vitamin D3 metabolite levels remained unchanged. However, vitamin D3 treatment resulted in a 2-4-fold greater increase in serum concentrations compared to vitamin D2 treatment. Treatment with vitamin D2 and vitamin D3 in the same dose in IU results in considerably different serum concentrations of the vitamin D metabolites.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Adult; Aged; Calcifediol; Calcium; Cholecalciferol; Dihydroxycholecalciferols; Epilepsy; Ergocalciferols; Female; Humans; Male; Middle Aged; Phenobarbital; Phenytoin

Twenty boys were followed during their puberty for about 2 years with examinations every third month. At each examination we determined serum concentrations of 25OHD3, 1,25(OH)2D3, 24,25(OH)2D3, 25.26(OH)2D3, alkaline phosphatase (AP) and testosterone together with bone mineral content (BMC) at the distal forearm. Highly significant increases in both BMC (P less than 0.001), serum AP (P less than 0.001), and peak height velocity (PHV) followed the increase in serum testosterone. The boys were grouped according to time of maximal increase in BMC, AP, and PHV. The serum levels of the vitamin D metabolites were related to these points. No significant changes in any of the serum vitamin D metabolites were found. Thus vitamin D metabolism does not seem to be significantly influenced during the period of life when both the linear growth and bone mineralization is maximal.

Topics: 24,25-Dihydroxyvitamin D 3; Adolescent; Alkaline Phosphatase; Bone and Bones; Calcifediol; Calcitriol; Child; Dihydroxycholecalciferols; Growth; Humans; Male; Minerals; Puberty; Testosterone; Vitamin D

The serum concentrations of the vitamin D metabolites 25-OHD, 1,25-(OH)2D, 24,25-(OH)2D and 25,26-(OH)2D, and of vitamin D binding protein (DBP), were determined longitudinally in 22 vitamin D supplemented pregnant women, and in 17 age-matched non-pregnant women studied during the summer. The pregnant women had higher 25-OHD and 1,25-(OH)2D, similar 24,25-(OH)2D, and lower 25,26-(OH)2D concentrations than the non-pregnant group. The relative concentrations of 24,25-(OH)2D and 25,26-(OH)2D (expressed as the molar ratio of these metabolites to 25-OHD) were lower during pregnancy. The DBP levels were increased in pregnancy, but the calculated free fraction (i.e. not bound to DBP) of the hormonal form of vitamin D, 1,25-(OH)2D, was still persistently higher in the pregnant than in the non-pregnant women. The study suggests that a daily vitamin D supplement of 400 IU satisfies the vitamin D requirement of pregnant women living in a cool climate with limited sun exposure. The increased absolute and relative concentration of 1,25-(OH)2D and decreased relative levels of 24,25-(OH)2D and 25,26-(OH)2D further suggest that the increased intestinal calcium and phosphate absorption, which is known to occur during pregnancy, is at least partially mediated by the vitamin D endocrine system.

Topics: 24,25-Dihydroxyvitamin D 3; Adult; Alkaline Phosphatase; Calcitriol; Calcium; Dihydroxycholecalciferols; Female; Humans; Hydroxycholecalciferols; Longitudinal Studies; Phosphates; Pregnancy; Vitamin D; Vitamin D-Binding Protein

To determine the effect of supplemental dietary vitamin D3 on concentration of vitamin D and its metabolites in milk, 20 Holstein cows were assigned to four groups and fed either 0, 10,000, 50,000, or 250,000 IU of vitamin D3/d beginning approximately 2 wk prepartum and continuing through wk 12 of lactation. Samples of blood plasma and milk were assayed for concentrations of vitamin D, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D. Only the daily dosage of 250,000 IU caused significant increases of concentrations of vitamin D or 25-hydroxyvitamin D in plasma. Concentrations of vitamin D and 25-hydroxyvitamin D in milk were approximately equal and averaged .2 ng/ml. Little 1,25-dihydroxyvitamin D and no 24,25-dihydroxyvitamin D could be detected in milk from any of the four treatment groups. Cows fed 250,000 IU of vitamin D3/d produced milk containing 54 IU of vitamin D activity per liter, whereas unsupplemented cows produced milk containing 17 IU/L. Oral supplementation with up to 250,000 IU of vitamin D3/d does not increase effectively vitamin D activity of milk.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Cattle; Cholecalciferol; Dihydroxycholecalciferols; Female; Food, Fortified; Milk; Pregnancy; Vitamin D

A specific mass fragmentographic assay for the measurement of 25,26-dihydroxyvitamin D3 [25,26(OH)2D3] in human plasma, using a stable isotope labelled internal standard ([26,27-2H5]25,26(OH)2D3), is described. Plasma samples (5 ml) were extracted with acetonitrile and applied to a C18 Sep-Pak cartridge, from which the vitamin D metabolites were eluted with methanol. The metabolites were then applied to a Sep-Pak SIL cartridge and three fractions were collected. The most polar fraction, containing the polyhydroxylated metabolites, was further purified by high-performance liquid chromatography on Zorbax SIL. The eluent containing 25,26(OH)2D3 was collected, and the 25,26-n-butylboronate cyclic ester 3-trimethylsilyl ether derivative was formed. Gas chromatography-mass spectrometry was carried out, monitoring the intensities of the ions at m/z 449 and m/z 454 (for the internal standard). These ions represent the loss of a methyl group and the 3-silanol group, (M-90-15)+. The minimum limit of detection of the assay was estimated to be approximately 0.05 microgram/l. Inter-assay (3.7%) and intra-assay (8.0%) precision was acceptable and added 25,26(OH)2D3, over the concentration range 0.5-1.5 microgram/l, was recovered quantitatively. The plasma 25,26(OH)2D3 level was estimated in 26 healthy volunteers and ranged from 0.05 to 1.30 microgram/l, with a mean value of 0.54 microgram/l.

Topics: 24,25-Dihydroxyvitamin D 3; Chemical Phenomena; Chemistry; Chromatography, High Pressure Liquid; Deuterium; Dihydroxycholecalciferols; Gas Chromatography-Mass Spectrometry; Humans; Mass Spectrometry; Reference Values; Time Factors

The effects of six natural vitamin D metabolites of potential biological and therapeutic interest, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), 25-hydroxyvitamin D3 (25-OH-D3), 24R,25-dihydroxyvitamin D3 (24R,25-(OH)2D3), 1,24R,25-trihydroxyvitamin D3 (1,24R,25-(OH)3D3), 25S,26-dihydroxyvitamin D3 (25S,26-(OH)2D3) and 1,25S,26-trihydroxyvitamin D3 (1,25S,26-(OH)3D3) on cell replication and expression of the osteoblastic phenotype in terms of osteocalcin production were examined in cultured human bone cells. At a dose of 5 X 10(-12) mol/1, 1,25-(OH)2D3 stimulated cell proliferation, whereas at higher doses (5 X 10(-9)-5 X 10(-6) mol/1) cell growth was inhibited in a dose-dependent manner. The same pattern of effects was seen for the other metabolites in a rank order of potency: 1,25-(OH)2D3 greater than 1,25S,26-(OH)3D3 = 1,24R,25-(OH)3D3 greater than 25S,26-(OH)2D3 = 24R,25-(OH)2D3 = 25-OH-D3. Synthesis of osteocalcin was induced by 1,25-(OH)2D3 in doses similar to those required to inhibit cell proliferation. Biphasic responses were observed for some of the metabolites in terms of osteocalcin synthesis, inhibitory effects becoming apparent at 5 X 10(-6) mol/1. The cells did not secrete osteocalcin spontaneously. These results indicate that vitamin D metabolites may regulate growth and expression of differentiated functions of normal human osteoblasts.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Calcium-Binding Proteins; Cell Division; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; In Vitro Techniques; Osteoblasts; Osteocalcin; Vitamin D

Metabolites of vitamin D were measured in plasma from 83 patients with idiopathic infantile hypercalcaemia syndrome who were mentally handicapped but had normal calcium values at the time of the study. No significant difference was detected in the mean plasma concentrations of 25-hydroxyvitamin D2, 1,25-dihydroxyvitamin D, 24,25-dihydroxyvitamin D3, or 25,26-dihydroxyvitamin D3 between patients and age matched controls. The mean plasma concentration of 25-hydroxyvitamin D3 was significantly lower in patients than controls but this may be a secondary phenomenon related to less sunlight exposure. In addition, two hypercalcaemic patients with this syndrome were studied during the first year of life, and were found to have normal concentrations of vitamin D metabolites. These findings do not support a role for abnormal vitamin D metabolism in the pathogenesis of this syndrome.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Adolescent; Calcitriol; Calcium; Child; Dihydroxycholecalciferols; Ergocalciferols; Female; Humans; Hydroxycholecalciferols; Hypercalcemia; Infant; Intellectual Disability; Male; Syndrome; Vitamin D

Serum concentrations of the main vitamin D metabolites and of calcium, phosphate, and alkaline phosphatase were determined in each of the three trimesters of pregnancy and in simultaneously obtained maternal and cord blood at delivery in 22 epileptic women treated with diphenylhydantoin or carbamazepine alone or with a combination with one other drug. The results were compared with similarly obtained data from 22 normal pregnancies. Women in both groups received supplements of 400 IU vitamin D3 per day. All the women had 25-hydroxyvitamin D levels within the normal range for healthy adults (greater than 12 ng/ml) throughout pregnancy. The epileptic women had, however, significantly (p less than 0.05) lower median 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels and higher median 25,26-dihydroxyvitamin D values than the reference group. The 24,25-dihydroxyvitamin D concentrations did not differ significantly, but the median ratio of 24,25-dihydroxyvitamin D to 25-hydroxyvitamin D was higher in the epileptic women at the end of pregnancy (p = 0.05). The respective differences in cord serum concentrations reflected those of the mothers at delivery. Serum calcium tended to be lower during epileptic pregnancy, but none were hypocalcemic. The alkaline phosphatase and phosphate values did not consistently differ from those of the reference women. The median alkaline phosphatase level of cord serum was slightly higher in the epileptic group, but the calcium and phosphate levels were similar to the reference values. The various biochemical parameters of the carbamazepine-treated women tended to be intermediate between those of the healthy and diphenylhydantoin-treated groups. Antiepileptic drug therapy appears to affect vitamin D metabolism and calcium homeostasis during pregnancy. The derangements may not be of major clinical significance, however, in vitamin D-supplemented and normally functioning women on long-term low-dose therapy.

Topics: 24,25-Dihydroxyvitamin D 3; Adolescent; Adult; Alkaline Phosphatase; Anticonvulsants; Calcifediol; Calcitriol; Calcium; Carbamazepine; Cholecalciferol; Dihydroxycholecalciferols; Epilepsy; Female; Fetal Blood; Homeostasis; Humans; Phenytoin; Phosphates; Pregnancy; Pregnancy Complications; Vitamin D

The circulating concentrations of 1,25-dihydroxyvitamin D and 24,25-dihydroxyvitamin D are abnormally low in patients with chronic renal failure (CRF). To determine the importance of substrate (25-hydroxyvitamin D) concentration in this phenomenon, five patients with end stage renal disease treated with hemodialysis were given 25-hydroxyvitamin D3 (25-OH-D3) orally for 4 weeks. The serum concentration of 25-OH-D3 increased from a mean (+/- SEM) of 26 +/- 5 ng/ml immediately before therapy to a maximum of 108 +/- 5 ng/ml 4 weeks after beginning administration of 25-OH-D3. The concentrations of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 24,25-dihydroxyvitamin D3 (24,25(OH)2D3), and 25,26-dihydroxyvitamin D3 (25,26(OH)2D3) increased from 6.6 +/- 0.8 pg/ml, 0.29 +/- 0.10 ng/ml, and 0.36 +/- 0.06 ng/ml, respectively, immediately before 25-OH-D3 administration to 21.7 +/- 2.2 pg/ml, 0.48 +/- 0.09 ng/ml; and 0.78 +/- 0.12 ng/ml, respectively, after 4 weeks of administration of 25-OH-D3. These results suggest that substrate availability may be an important determinant of the circulating concentrations of these metabolites in patients with CRF. It seems possible that the therapeutic effects of 25-OH-D3 administration to the CRF patient may be mediated through the normal actions of 1,25-dihydroxyvitamin D3, 24,25-dihydroxyvitamin D3, and perhaps other metabolites rather than through analog effects of 25-OH-D3.

Topics: 24,25-Dihydroxyvitamin D 3; Administration, Oral; Calcifediol; Calcitriol; Dihydroxycholecalciferols; Humans; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Vitamin D

This paper describes a specific mass-fragmentographic method, involving a stable-isotope-labeled internal standard, for measurement of 24,25-dihydroxyvitamin D in human plasma. Vitamin D metabolites were rapidly extracted from plasma by using Sep-Pak C18 cartridges and separated into fractions on Sep-Pak SIL cartridges. The polar fraction, containing the dihydroxylated metabolites, was further purified by "high-performance" liquid chromatography on Zorbax SIL. The fraction containing 24,25-dihydroxyvitamin D was collected, evaporated, and converted to the 24:25-cyclic n-butyl boronate-3-trimethylsilyl ether derivative before analysis by gas chromatography-mass spectrometry. The intensity of the mass fragment (m/z 449, m/z 455 for the hexadeuterated internal standard) arising from the loss of one of the angular methyls and the 3-silanol group [( M-90-15]+) was monitored. The minimum limit of detection for this method is about 0.1 microgram/L. Inter- and intra-assay reproducibility was acceptable, and analytical recovery of added 24,25-dihydroxyvitamin D3 over the concentration range 1.0 to 5.0 micrograms/L was quantitative. Concentrations of 24,25-dihydroxyvitamin D3 in plasma of 21 apparently healthy volunteers were between 0.55 and 5.39 micrograms/L, higher values being obtained after prolonged exposure to the sun. No 24,25-dihydroxyvitamin D2 could be detected in any plasma sample examined.

Topics: 24,25-Dihydroxyvitamin D 3; Chromatography, High Pressure Liquid; Deuterium; Dihydroxycholecalciferols; Ergocalciferols; Gas Chromatography-Mass Spectrometry; Humans; Isotope Labeling; Reference Standards; Reference Values; Seasons; Trimethylsilyl Compounds

Plasma concentrations of 1,25-dihydroxyvitamin D [1,25-(OH)2D], 24,25-dihydroxyvitamin D [24,25-(OH)2D], and 25,26-dihydroxyvitamin D [25,26-(OH)2D] were determined in 80 healthy infants of 4 days, 6 weeks, 6 months, and 12 months of age. The 4-day-old babies received breast milk, while the 6-week-old infants were either exclusively breast or formula fed. The older infants were on mixed diets and received daily vitamin D supplements. The levels were analyzed with regard to age and the concentrations of 25-hydroxyvitamin D (25OHD), calcium, phosphate, magnesium, and alkaline phosphatase and were compared with adult levels of vitamin D metabolites. The median 1,25-(OH)2D concentration was highest at 4 days of age and lowest at 6 weeks, but, except for the 6-week-old group, all had higher levels than the adults (6 weeks, P less than 0.1; others, P less than 0.01). 1,25-(OH)2D and 25OHD levels showed significant correlation only at 4 days (r = 0.74; P less than 0.0005), and there were no consistent relationships between 1,25-(OH)2D and the other variables. The median concentration of 24,25-(OH)2D was lower (P less than 0.01), while the 25,26-(OH)2D value was similar to that in the adults. Both were, however, positively related to the 25OHD level [24,25-(OH)2D, r = 0.82; 25,26-(OH)2D, r = 0.65; P less than 0.0005], as in the adults. The ratio of 24,25-(OH)2D to 25OHD was lower beyond 4 days of life than in the adults (medians, 3.4% vs. 5.1%; P less than 0.02). The data suggest that 1,25-(OH)2D synthesis has relative priority over 24,25-(OH)2D production during infancy compared with that in adulthood.

Topics: 24,25-Dihydroxyvitamin D 3; Adult; Alkaline Phosphatase; Breast Feeding; Calcitriol; Calcium; Dihydroxycholecalciferols; Humans; Infant; Infant, Newborn; Magnesium; Phosphates

The metabolism of vitamin D3 was studied in bilaterally nephrectomized pigs and cotnrol pigs maintained for 8-10 days by daily peritoneal dialysis. Two or three pharmacological doses of vitamin D3 were given im, one on day 0 and the others on days, 4, 6, or 7 of the 8- to 10-day experimental periods. Nephrectomized pigs had extremely high plasma concentrations of 24,25-dihydroxyvitamin D3 [24,25-(OH)2D3] and 25,26-(OH)2D3 at the end of the 8- to 10-day periods; similar levels were present in control pigs. However, nephrectomized pigs had no detectable increase in plasma 25-hydroxyvitamin D3 (25OHD3)-26,23-lactone concentrations throughout the experiment, in contrast with the high plasma concentrations of 25OHD3-26,23-lactone in the control pigs. Much higher plasma 25OHD3 concentrations were present in the nephrectomized pigs than in the control pigs. Plasma 1,25-(OH)2D concentrations in nephrectomized and control pigs were similar during most of the experiment, except the anephric pigs usually had significantly higher plasma 1,25-(OH)2D concentrations for several days after the vitamin D3 injections. These studies demonstrate extrarenal production of 24,25-(OH)2D3, 25,26-(OH)2D3, and possibly 1,25-(OH)2D, and kidney-dependent synthesis of 25OHD3-26,23-lactone in the pigs.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcitriol; Calcium; Cholecalciferol; Dihydroxycholecalciferols; Female; Male; Nephrectomy; Swine

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcitriol; Calcium; Cholecalciferol; Culture Media; Dihydroxycholecalciferols; Ethanol; In Vitro Techniques; Male; Parathyroid Glands; Parathyroid Hormone; Rats; Rats, Inbred Strains

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Chickens; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Hydroxycholecalciferols; Hydroxylation; Kidney; Tritium; Vitamin D Deficiency

To relate the vitamin D metabolism in puberty to sex, sexual maturation, and, indirectly, to growth velocity and cessation of growth, the plasma level of 25-hydroxy vitamin D, 1,25-dihydroxyvitamin D [1,25-(OH)2D], 24,25-dihydroxyvitamin D [24,25-(OH)2D], and 25,26-(OH)2D were measured in 191 adolescents representing all stages of puberty. In girls, 1,25-(OH)2D3 increased from age 11 yr to a peak at 12 yr of age (P less than 0.0005) and then decreased. In boys, the increase occurred between 13--14 yr of age (P less than 0.005), with a subsequent decline. When the 1,25-(OH)2D concentrations were related to the stage of puberty, the girls showed a maximal increase between stages 1 and 2 (P less than 0.0005), with a peak at stage 3, whereas the boys had a significant increase from stage 2 to a peak at stage 3 (P less than 0.01). In both sexes, there were subsequent significantly decreasing values to stage 4 through stage 5. The ratio of 24,25-(OH)2D to 25-hydroxyvitamin D varied inversely with the 1,25-(OH)2D concentration, with the lowest value at age 12 yr in both sexes, followed by a gradual increase to a plateau at age 15 yr in girls and 17 yr in boys. It appears that the hormones of the vitamin D system add another dimension to the endocrinology of growth and puberty.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Adolescent; Alkaline Phosphatase; Calcitriol; Calcium; Child; Diet; Dihydroxycholecalciferols; Ergocalciferols; Female; Humans; Male; Phosphates; Puberty; Sex Factors; Sexual Maturation; Vitamin D

Here we report the use of newly developed and established techniques for the determination of plasma levels of a broad spectrum of vitamin D3 metabolites, including vitamin D3 and 25OHD3-lactone, in normal humans, chronic renal failure patients, and anephric subjects. The methodology described consisted of methanol-methylene chloride extraction, Lipidex-5000 chromatography with stepwise gradient elution, normal-phase HPLC with concave gradient elution, and sensitive ligand-binding assays. The results of the study strongly suggest an extrarenal source(s) for 24,25(OH)2D3 and 25,26(OH)2D3 and indicate that both 25OHD3-lactone and 1,25(OH)2D3 may be produced solely in the kidney of the human. Significant reductions or nondetectable plasma levels of vitamin D3 in the renal disease patients may reflect abnormalities in the hepatobiliary-intestinal and/or cutaneous metabolism of vitamin D.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Cholecalciferol; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Kidney Failure, Chronic; Methods; Nephrectomy

A 9-month-old boy who had the mild form of idiopathic infantile hypercalcemia was observed for 18 months. During the initial hypercalcemic stage, the serum concentration of 25-hydroxyvitamin D was normal. Urinary levels of cyclic adenosine monophosphate (cAMP) were low, and the serum concentrations of the dihydroxyl metabolites of vitamin D were appropriate to the high serum calcium concentration, with low 1,25-dihydroxyvitamin D and relatively high 24,25- and 25,26-dihydroxyvitamin D levels. Throughout the study period, there was a close positive correlation between the magnitude of the urinary cAMP excretion and the serum level of 1,25-dihydroxyvitamin D. The results indicate that excessive vitamin D intake leading to high serum levels of 25-hydroxyvitamin D are not decisive factors in the pathogenesis of idiopathic infantile hypercalcemia.

Topics: 24,25-Dihydroxyvitamin D 3; 25-Hydroxyvitamin D 2; Calcitriol; Cyclic AMP; Dihydroxycholecalciferols; Ergocalciferols; Humans; Hypercalcemia; Infant; Male; Phosphates; Phosphorus; Vitamin D

Human and bovine milk were analyzed for vitamin D, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, 25,26-dihydroxyvitamin D and 1,25-dihydroxyvitamin D using exhaustive chromatographic purification procedures coupled with ligand binding assays. Human milk contained the following amounts of antirachitic sterols (pg/ml, mean +/- SD, n = 5): 39 +/- 9 vitamin D; 311 +/- 31 25-hydroxyvitamin D; 52 +/- 8 24,25-hydroxyvitamin D; 32 +/- 9 25,26-dihydroxyvitamin D; 5.1 +/- 0.3 1,25-dihydroxyvitamin D. Normal bovine milk contained levels of these sterols comparable to those found in human milk. Increasing the oral dose of vitamin D to the cows was reflected by an increase of the parent vitamin and 25-hydroxyvitamin D in the milk. Vitamin D-binding protein concentration in human milk whey, determined by Ouchterlony immunodiffusion and radioimmunoassay, was 1--2% of the levels observed in the plasma and was dependent on the stage of lactation. Vitamin D and its metabolites were shown initially to be present in the whey portion but with time migrated into the fat portion of milk. The antirachitic sterols detected account for approximately 25 IU/liter and 27 IU/liter of antirachitic activity in human and bovine milk, respectively. In both species 25-hydroxyvitamin D comprised the majority of the antirachitic sterols detected in normal milk.

Topics: 24,25-Dihydroxyvitamin D 3; Animals; Calcifediol; Calcitriol; Cattle; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Female; Humans; Hydroxycholecalciferols; Immunodiffusion; Lactation; Milk; Milk, Human; Pregnancy; Radioligand Assay; Vitamin D

We have examined the effects of metabolites of vitamin D [25OHD3, 1,25(OH)2D3, 24,25(OH)2D3, and 25,26(OH)2D3] on serum calcium and iPTH in human deficient-D osteomalacia. The four metabolites decreased iPTH, but only for 1,25(OH)2D3 was a significant correlation between increase of serum calcium and decrease of iPTH observed. The 24,25(OH)2D3 and 25,26(OH)2D3 decreased iPTH despite a decrease of serum calcium at the beginning of treatment. The 25OHD decreased iPTH before increased serum calcium. These results could be interpreted as a direct effect of metabolites of vitamin D on PTH secretion. However, the conversion of other metabolites and the calcium concentration in parathyroid cells must be determined before this hypothesis can be accepted.

Topics: 24,25-Dihydroxyvitamin D 3; Adult; Calcifediol; Calcium; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Middle Aged; Osteomalacia; Parathyroid Hormone

A method for extraction, separation and purification of the main serum metabolites of vitamin D from a single serum sample is described. The method involved extraction of serum by diethylether and separation and purification of vitamin D, 25-OHD and the dihydroxymetabolites 24,25-(OH)2D, 25,26-(OH),2D and 1,25-(OH)2D by elution in three steps from a short open silicic acid column. The eluted vitamin D metabolites were further separated and purified by high pressure liquid chromatography (HPLC). The HPLC systems described separated the D2 and D3 forms of vitamin D, 25-OHD, 1,25-(OH)2D, and probably also 24,25-(OH)2D and 25,26-(OH)2D. The metabolites were purified by the methods described for further quantitation by UV-absorption or competitive protein binding assays, and were found to be homogenous on re-chromatography with different HPLC systems. Good recoveries were obtained for all the metabolites.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Silicic Acid; Vitamin D; Vitamin K

The ability of four solvent systems to extract tritiated 25-hydroxy vitamin D3, 24,25-dihydroxy vitamin D3, 25,26-dihydroxy vitamin D3 and 1 alpha, 25-dihydroxy vitamin D3 from plasma was compared. Diethyl ether gave the highest yield of metabolites and lowest yield of "lipid" materials, the dihydroxylated metabolites were more readily extracted than 25-hydroxy vitamin D3. Following extraction with ether the vitamin D metabolites could be separated, without prior purification, on a 6.2 mm X 250 mm Zorbax-Sil high pressure liquid chromatography (HPLC) column, a simplification of previous methods. Plasma 1 alpha, 25-dihydroxy vitamin D levels measured after purification by this method were not significantly different from those obtained by an established, more complex method.

Topics: 24,25-Dihydroxyvitamin D 3; Calcifediol; Calcitriol; Chromatography, High Pressure Liquid; Dihydroxycholecalciferols; Humans; Hydroxycholecalciferols; Radioimmunoassay; Solubility; Vitamin D