Circulating Levels of Vitamin D Metabolites after Renal Transplantation

ABSTRACTObjectiveEpidemiological studies suggest vitamin D deficiency as a potential risk factor for rheumatoid arthritis (RA) development, a chronic autoimmune disorder highly prevalent in indigenous North American (INA) population. We therefore profiled the circulating levels of 25-hydroxyvitaminD [25(OH)D], an active metabolite of vitamin D, in a cohort of at-risk first-degree relatives (FDR) of INA RA patients, a subset of whom subsequently developed RA (progressors).Methods2007 onward, serum samples from INA RA patients and FDR were collected at the time of a structured baseline visit and stored at −20°C. Anti-citrullinated protein antibodies (ACPA), 25(OH)D, hs-CRP, vitamin-D binding protein (VDBP) levels were determined using ELISA and rheumatoid factor (RF) seropositivity was determined by nephelometry.ResultsWe demonstrate that 25 (OH) D concentrations were lower in winter than summer (P=0.0538), and that serum 25(OH)D levels were higher in samples collected and stored after 2013 (P<0.0001). Analysis of samples obtained after 2013 demonstrated that 37.6% of study participants were 25(OH)D insufficient (<75nmol/L). Also, seropositive RA patients and FDR had lower 25(OH)D levels compared to ACPA-/FDR (P<0.05, P<0.01 respectively). Linear regression analysis showed 25(OH)D insufficiency was inversely associated with presence of RA autoantibodies. Longitudinal samples from 14 progressors demonstrated a consistent increase in 25(OH)D levels at the time they exhibited clinically detectable joint inflammation, without any significant change in VDBP levels.ConclusionWe demonstrate that 25(OH)D levels in serum increased at RA onset in progressors. The potential role that vitamin D metabolites and their downstream effects play in RA transition requires further investigation.

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Circulating levels of calciotropic hormones during treatment with nasal salmon calcitonin

Acta Endocrinologica ◽

10.1530/acta.0.1250127 ◽

1991 ◽

Vol 125 (2) ◽

pp. 127-131 ◽

Cited By ~ 6

Author(s):

Gorm Thamsborg ◽

Tommy L. Storm ◽

Henrik Daugaard ◽

Søren Schifter ◽

Ole H. Sørensen

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Nasal Spray ◽

Salmon Calcitonin ◽

Serum Levels ◽

Treated Group ◽

Human Calcitonin ◽

Vitamin D Metabolites ◽

Calciotropic Hormones ◽

Circulating Levels

Abstract. Circulating levels of calciotropic hormones were measured during one year of treatment with either 200 IU of salmon calcitonin daily or placebo as a nasal spray in 20 postmenopausal women with a former Colles' fracture. A supplement of 0.5 gram elemental calcium was given to all participants. Serum levels of parathyroid hormone and human calcitonin were determined with radioimmunoassays, and serum levels of vitamin D metabolites were determined with protein binding assays. We did not find any significant differences between the two groups with respect to serum levels of calciotropic hormones. In the salmon calcitonin treated group there was a tendency towards a small decrease in serum levels of human calcitonin and an increase in serum levels of calcitriol. Our results suggest that treatment with 200 IU of salmon calcitonin daily as a nasal spray does not markedly affect fasting serum levels of parathyroid hormone, human calcitonin, and vitamin D metabolitis.

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Elevated 1,25-dihydroxyvitamin D3 and intestinal calbindin-D9k in the toothless rat

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.258.2.e377 ◽

1990 ◽

Vol 258 (2) ◽

pp. E377-E381

Author(s):

M. F. Seifert ◽

R. W. Gray ◽

M. E. Bruns

Keyword(s):

Vitamin D ◽

Calcium Binding ◽

Morphological Evidence ◽

Vitamin D Metabolites ◽

Dihydroxyvitamin D3 ◽

1,25 Dihydroxyvitamin D3 ◽

Calbindin D9k ◽

Plate Morphology ◽

Circulating Levels ◽

Phosphorus Levels

The toothless (tl) rat is a nonlethal osteopetrotic mutation characterized by systemic skeletal sclerosis, growth plate morphology suggestive of rickets, and morphological evidence of reduced osteoclastic bone resorption. Vitamin D metabolites, serum calcium and phosphorus levels, and the developmental appearance of vitamin D-dependent intestinal calcium binding protein (calbindin-D9k) was studied in normal and mutant rats of tl stock from 7 to 35 days of age. 1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] was found to be significantly elevated in mutant animals by 7 days of age (71 +/- 9 pM, tl/tl vs. 24 +/- 8 pM, +/?) and continued to increase to a peak of 428 pM at the time of weaning. This was 240% higher than normals at this period. The elevated levels of 1,25-(OH)2D3 stimulated a significant and precocious appearance of intestinal calbindin-D9k in mutants, beginning by 14 days of age and reaching their peak levels at 21 days postpartum (25.6 +/- 1.7 micrograms/mg protein, tl/tl vs. 16.4 +/- 1.5 micrograms/mg protein, +/?). The cause of the elevated circulating levels of 1,25-(OH)2D3 in tl rats is unknown but may be due to the low serum phosphorus levels present in these animals.

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