25-Hydroxyvitamin D Can Interfere With a Common Assay for 1,25-Dihydroxyvitamin D in Vitamin D Intoxication

Abstract We describe a simplified assay for 24,25-and 1.25-dihydroxyvitamin D in human serum. It involves two preparative steps, and normal chick intestine is used in preparing cytosol-binding protein. Our results for 24,25-dihydroxyvitamin D include a reference interval of 2.9—16 nmol/L (1.2—6.7 microgram/L), a mean of 6.7 nmol/L (2.8 microgram/L), an intra-assay CV of 11%, and an interassay CV of 22%. For 1,25-dihydroxyvitamin D, these data were 29—168 pmol/L (12—70 ng/L), 86 pmol/L (36 ng/L), 12%, and 22%, respectively. In hypoparathyroid patients with vitamin D intoxication, mean concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum were significantly above normal; the 1,25-dihydroxyvitamin D concentrations were significantly below normal. Patients with malabsorption and/or post-gastrectomy states had significantly subnormal values for both 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum, and there was a significantly negative correlation between each of these biochemical values and the severity of osteomalacia. We also discuss cost effectiveness of assaying vitamin D metabolites in human serum.

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A simplified assay for dihydroxylated vitamin D metabolites in human serum: application to hyper- and hypovitaminosis D.

Clinical Chemistry ◽

10.1093/clinchem/26.3.444 ◽

1980 ◽

Vol 26 (3) ◽

pp. 444-450 ◽

Cited By ~ 54

Author(s):

R S Mason ◽

D Lissner ◽

H S Grunstein ◽

S Posen

Keyword(s):

Vitamin D ◽

Human Serum ◽

Hypovitaminosis D ◽

Reference Interval ◽

Vitamin D Metabolites ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Vitamin D Intoxication ◽

25 Hydroxyvitamin D

Abstract We describe a simplified assay for 24,25-and 1.25-dihydroxyvitamin D in human serum. It involves two preparative steps, and normal chick intestine is used in preparing cytosol-binding protein. Our results for 24,25-dihydroxyvitamin D include a reference interval of 2.9—16 nmol/L (1.2—6.7 microgram/L), a mean of 6.7 nmol/L (2.8 microgram/L), an intra-assay CV of 11%, and an interassay CV of 22%. For 1,25-dihydroxyvitamin D, these data were 29—168 pmol/L (12—70 ng/L), 86 pmol/L (36 ng/L), 12%, and 22%, respectively. In hypoparathyroid patients with vitamin D intoxication, mean concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum were significantly above normal; the 1,25-dihydroxyvitamin D concentrations were significantly below normal. Patients with malabsorption and/or post-gastrectomy states had significantly subnormal values for both 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in serum, and there was a significantly negative correlation between each of these biochemical values and the severity of osteomalacia. We also discuss cost effectiveness of assaying vitamin D metabolites in human serum.

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Extrarenal synthesis of 1,25-dihydroxyvitamin D: Sensitivity to glucocorticoid treatment

Clinical Science ◽

10.1042/cs0720329 ◽

1987 ◽

Vol 72 (3) ◽

pp. 329-334 ◽

Cited By ~ 3

Author(s):

Silvano Adami ◽

G. Graziani ◽

D. Tartarotti ◽

R. Cappelli ◽

S. Casati ◽

...

Keyword(s):

Vitamin D ◽

Serum Calcium ◽

Glucocorticoid Treatment ◽

Prednisone Therapy ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Prednisone Treatment ◽

Vitamin D Intoxication ◽

Before And After

1. The response of circulating 1,25-dihydroxyvitamin D [l,25-(OH)2D] to challenge with vitamin D treatment both before and after 7–10 days of prednisone therapy (25 mg/day) was investigated in five anephric subjects, six patients with chronic renal failure (CRF), two patients with vitamin D intoxication and four patients with hypoparathyroidism. 2. In anephric subjects serum 25-hydroxyvitamin D [25-(OH)D] rose from 58 ± 48 (sd) to 377±221 (sd) nmol/l after administration of 150 μg of 25-(OH)D3 for 1 month. Serum l,25-(OH)2D, which was barely detectable in only two out of five patients under basal conditions, rose to 30 ± 21 pmol/l after 2 weeks of therapy with 25-(OH)D3, but fell to 10 ± 5 pmol/l during prednisone treatment. 3. In CRF patients circulating l,25-(OH)2D rose from 37 ± 24 to 58 ± 24 pmol/l during 25-(OH)D3 therapy, but fell to 41 ± 31 pmol/l during prednisone treatment. In two patients with rheumatoid arthritis, hypercalcaemia due to vitamin D intoxication was associated with raised levels of 1,25-(OH)2D (288 and 317 pmol/l). Administration of prednisore resulted in suppression of l,25-(OH)2D levels (132 and 96 pmol/l respectively) and reduction of serum calcium to within the normal range. 4. In the hypoparathyroid patients prednisone therapy did not affect circulating 25-(OH)D levels but serum l,25-(OH)2D fell from 192 ± 42 to 117 ± 23 pmol/l and serum calcium from 2.41 ± 0.21 to 2.20 ± 0.05 mmol/l. 5. These findings indicate that a steroid sensitive extrarenal production of l,25-(OH)2D may occur in all subjects with a threshold serum concentration of the precursor 25-(OH)D.

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Responses of serum calcium and phosphorus in the frog Rana tigrina to injection of various vitamin D analogs

Canadian Journal of Zoology ◽

10.1139/z87-323 ◽

1987 ◽

Vol 65 (8) ◽

pp. 2111-2112 ◽

Cited By ~ 4

Author(s):

Ajai K. Srivastav ◽

L. Rani ◽

K. Swarup

Keyword(s):

Vitamin D ◽

Serum Calcium ◽

Vitamin D Analogs ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Rana Tigrina ◽

Calcium Deposits ◽

25 Hydroxyvitamin D ◽

Calcium And Phosphorus

Intraperitoneal injections of either vitamin D3 (4 IU/100 g body wt.), 25 hydroxyvitamin D3 (100 ng/100 g body wt.), or 1,25 dihydroxyvitamin D3 (100 ng/100 g body wt.) for 15 days induced hypercalcemia, hyperphosphatemia, and depletion of calcium deposits in the paravertebral lime sacs in an anuran, Rana tigrina.

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Cyclosporin a and Vitamin D Metabolism: Studies in Patients with Psoriasis and in Rats

Clinical Science ◽

10.1042/cs0860627 ◽

1994 ◽

Vol 86 (5) ◽

pp. 627-632 ◽

Cited By ~ 3

Author(s):

A. J. Shaw ◽

M. E. Hayes ◽

M. Davies ◽

B. D. Edwards ◽

F. W. Ballardie ◽

...

Keyword(s):

Vitamin D ◽

Synovial Fluid ◽

Cyclosporin A ◽

Severity Index ◽

Hydroxylase Activity ◽

Local Synthesis ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

25 Hydroxyvitamin D

1. Cyclosporin A, an immunosuppressive drug used to treat psoriasis, stimulates renal synthesis of 1,25-dihydroxyvitamin D in rats. 1,25-Dihydroxy vitamin D can also reduce the activity of psoriasis, and in the present study we have examined the possibility that cyclosporin A mediates some of its actions in psoriasis by renal or extra-renal production of 1,25-dihydroxyvitamin D. 2. Treatment of 12 psoriatic patients with cyclosporin A (5 mg day−1 kg−1) for 3 months significantly improved the psoriasis activity and severity index and reduced glomerular filtration rate, but serum 1,25-dihydroxyvitamin D levels were not changed. However, 1–3 months after stopping cyclosporin A treatment, an increase in the psoriasis activity and severity index score was accompanied by a small, but significant, increase in serum 1,25-dihydroxyvitamin D concentration. Plasma 1,25-dihydroxyvitamin D levels in rats gavaged with cyclosporin A (15 mg day−1 kg−1 for 2 weeks) were significantly increased compared with controls, but a lower dose of cyclosporin A (2.4 mg day−1 kg−1) had no effect. Renal 25-hydroxyvitamin D-24-hydroxylase activity in rat kidney homogenates was not different between control and cyclosporin A-treated rats. Renal 25-hydroxyvitamin D-1α-hydroxylase activity was not detectable in these homogenates. Extra-renal production of 1,25-dihydroxyvitamin D by activated macrophages isolated from the synovial fluid of patients with inflammatory arthritis was reduced after incubation with cyclosporin A (0.1–10 μmol/l) for 30 h or 5 days. 3. It is unlikely that alteration of circulating 1,25-dihydroxyvitamin D concentration is one of the modes of action of cyclosporin A in psoriasis. Since cyclosporin A inhibits 1,25-dihydroxyvitamin D production by activated synovial fluid macrophages, it is unlikely that cyclosporin A mediates some of its therapeutic actions by local synthesis of 1,25-dihydroxyvitamin D within the psoriatic lesion.

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Vitamin D and Calcitonin Treatment in Patients with Femoral Neck Fracture: A Prospective Controlled Clinical Study

Journal of International Medical Research ◽

10.1177/030006058901700305 ◽

1989 ◽

Vol 17 (3) ◽

pp. 226-242 ◽

Cited By ~ 9

Author(s):

E. Harju ◽

R. Punnonen ◽

R. Tuimala ◽

J. Salmi ◽

I. Paronen

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Serum Levels ◽

Serum Calcitonin ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Age Related ◽

Neck Fracture ◽

25 Hydroxyvitamin D

The effects on general and bone metabolism of femoral neck fracture patients of 0.25 μg α-calcoid given orally twice daily ( n=9) and 25 μg calcitonin given subcutaneously 30 times ( n=10) in 10 weeks were studied against a control ( n=ll). Bone histology and histomorphometry showed non-age related osteoporosis in 30% and osteomalacia in 22% of the patients studied. Impaired serum vitamin D status was found in 47 – 88% of patients, secondary hyperparathyroidism and increased serum parathyroid hormone in 59% and decreased serum calcitonin levels in 69%. On histology, normal findings and non-age related osteoporosis on histology were associated with low serum levels of 25-hydroxyvitamin D3,1,25- and 24,25-dihydroxy vitamin D3. Very high serum levels of 1,25-dihydroxyvitamin D3 and low levels of 25-hydroxyvitamin D3 occurred in fracture patients with osteomalacia. Calcitonin improved calcium balance, reduced osteoporosis and increased the serum 1,25- and 24,25-dihydroxyvitamin D3 levels but had no effect on osteomalacia. Vitamin D reduced osteomalacia, slightly increased the serum 1,25-dihydroxyvitamin D3 concentration and decreased serum levels of parathyroid hormone. Both treatments gave a similar slight decrease in serum calcitonin concentrations. A mechanism of action for the treatments is suggested.

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1α-Hydroxyvitamin D3 Treatment of Three Patients With 1,25-Dihydroxyvitamin D-Receptor-Defect Rickets and Alopecia

PEDIATRICS ◽

10.1542/peds.80.1.97 ◽

1987 ◽

Vol 80 (1) ◽

pp. 97-101

Author(s):

E. Takeda ◽

Y. Kuroda ◽

T. Saijo ◽

E. Naito ◽

H. Kobashi ◽

...

Keyword(s):

Vitamin D ◽

Calcium Lactate ◽

Type Ii ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

25 Hydroxyvitamin D

Three patients with clinically different severities of vitamin D-dependent rickets, type II, with alopecia, which is 1,25-dihydroxyvitamin D-receptor-defect rickets and is particularly resistant to treatment with calciferol analogues, were treated with large doses of lα-hydroxyvitamin D3 (1α-(OH)D3) and 2 g of calcium lactate. Except for the alopecia, all of the abnormalities of patients 1 and 2 were reversed by treatment with 3 µg/kg/d of 1α-(OH)D3, and those of patient 3, who had the severest manifestations, were reversed by treatment with 6 µg/kg/d. The serum 24,25-dihydroxyvitamin D concentrations of the three patients were low before treatment and those of patients 1 and 2 increased during treatment. These findings suggest that in patients 1 and 2, 25-hydroxyvitamin D-24-hydroxylase was stimulated via a 1,25-dihydroxyvitamin D-receptor-mediated system by treatment with 1α-(OH)D3.

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Simultaneous determination of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D in plasma or serum.

Clinical Chemistry ◽

10.1093/clinchem/27.10.1757 ◽

1981 ◽

Vol 27 (10) ◽

pp. 1757-1760 ◽

Cited By ~ 17

Author(s):

M J Jongen ◽

W J van der Vijgh ◽

H J Willems ◽

J C Netelenbos ◽

P Lips

Keyword(s):

Vitamin D ◽

Vitamin D Metabolites ◽

Binding Assays ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Extraction And Purification ◽

Chromatographic Procedure ◽

25 Hydroxyvitamin D ◽

Liquid Chromatographic

Abstract We describe a simultaneous assay for the principal vitamin D metabolites: 25-hydroxyvitamin D, 24-25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D. Special attention has been paid to simplification of the extensive extraction and purification procedures used in previously described simultaneous assays. All three metabolites were isolated with a single extraction step, followed by only one gradient liquid-chromatographic procedure. For final quantitation we used competitive protein binding assays, involving readily available binding proteins and commercially purchased tritiated vitamin D metabolites. Concentrations in the plasma of healthy subjects (mean age, 27 years), sampled during December were 51 (SD 17) nmol/L, 4.1 (SD 1.3) nmol/L, and 124 (SD 26) pmol/L for 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D, respectively. Intra- and interassay CVs for the three metabolites were 4.4 and 3.9%, 6.7 and 8.0%, and 7.0 and 4.8%, respectively.

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Determinants of the serum concentration of 1,25-dihydroxyvitamin D in primary hyperparathyroidism

Clinical Science ◽

10.1042/cs0760081 ◽

1989 ◽

Vol 76 (1) ◽

pp. 81-86 ◽

Cited By ~ 16

Author(s):

B. C. Lalor ◽

E. B. Mawer ◽

M. Davies ◽

G. A. Lumb ◽

L. Hunt ◽

...

Keyword(s):

Vitamin D ◽

Serum Concentration ◽

Primary Hyperparathyroidism ◽

Serum Concentrations ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Relevant Variables ◽

Biological Determinants ◽

25 Hydroxyvitamin D

1. The serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were measured in 44 patients with primary hyperparathyroidism. 2. In 14 patients the serum concentration of 1,25-dihydroxyvitamin D was greater than normal (142–337 pmol/l). One patient had a subnormal concentration of 1,25-dihydroxyvitamin D (36 pmol/l) but no other evidence of vitamin D deficiency. 3. The possible biological determinants of the serum concentration of 1,25-dihydroxyvitamin D were sought by multivariate analysis of relevant variables. The serum concentration of 1,25-dihydroxyvitamin D was found to be significantly and positively correlated with the serum concentrations of 25-hydroxyvitamin D (P < 0.001) and parathyroid hormone (P < 0.003), and with the glomerular filtration rate (P < 0.03), and negatively correlated with the serum concentrations of calcium (P < 0.02) and phosphate (P = 0.055) (multiple R = 0.638,P < 0.002). 4. In primary hyperparathyroidism the major determinant of serum 1,25-dihydroxyvitamin D is the availability of precursor 25-hydroxyvitamin D. 5. The finding that serum 1,25-dihydroxyvitamin D is commonly normal in patients with primary hyperparathyroidism despite an adequate state of vitamin D nutrition, can be explained in terms of the constraining influences of hypercalcaemia and variable degrees of renal dysfunction on the biosynthesis of 1,25-dihydroxyvitamin D.

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