Reduction of circulating 25‐hydroxyvitamin D by antipyrine.

Wilmana, P. F.; Brodie, MJ; Mucklow, JC; Fraser, HS; Toverud, EL; Davies, DS; Dollery, C. T.; Hillyard, C. J.; MacIntyre, I.; Park, BK

doi:10.1111/j.1365-2125.1979.tb01039.x

Cited by 13 publications

(6 citation statements)

References 25 publications

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Section: Methodsmentioning

confidence: 95%

“…25-OHD concentrations were measured in plasma by a competitive protein-binding assay as previously described. 4 The sensitivity was 50 pg/tube, and intra-assay and interassay variations were 10 1%, and 13-2", respectively. 1 ,25-(OH),D concentrations were measured by a radioreceptor assay using an intestinal receptor preparation5 and a modified extraction and separation procedure by high-performance liquid chromatography (G Abeyasekera and I MacIntyre, unpublished data).…”

Section: Methodsmentioning

confidence: 95%

See 1 more Smart Citation

Interrelations of calcium-regulating hormones during normal pregnancy.

Whitehead¹,

Lane²,

Young³

et al. 1981

BMJ

Self Cite

133

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women at young ages, as one would expect; there was also a somewhat higher proportion aged over 70 compared with 30-69 years. There has been a tendency for the proportion of women having very large families to decrease, and this was again reflected by an increased proportion of women in the high parous group at older ages. The data were originally examined for those having three, four, or five or more children; it was particularly in those having five or more children that the proportion at the older age groups was higher.One crucial point about this study is whether it was appropriate to assume that the relative risk of breast cancer is constant within parity subgroups over a wide age range; unfortunately this issue has not been adequately quantified. The nearest set of data most relevant to this was a study by Miller et al,6 who examined the parity for women in three provinces in Canada registered with all forms of malignant disease in 1969-71. By special inquiry parity for these women was obtained and compared with the census data. The relative risk of breast cancer in women having four or more children compared with nulliparae was similar in the age ranges 20-44, 45-54, and 55 years and over.Applying England and Wales incidence rates to the age distribution of women by parity enabled the average age at diagnosis to be estimated; the results approximate to the findings of Woods et al.1 It was suggested that their result was a reflection of variation in the age distribution of women by parity, rather than any particular influence of parity on accelerating or slowing the date of presentation of breast cancer. The increased concentrations of 1,25-(OH)2D enable the increased physiological need for calcium to be met by enhancing intestinal absorption of this element. The simultaneous rise in calcitonin opposes the bone-resorbing activities of 1,25-(OH)2D, thereby protecting the integrity of the maternal skeleton. Maternal calcium homoeostasis is thus maintained yet the requirements of the fetus are fulfilled. IntroductionThe increased physiological requirement for calcium during pregnancy presents a major challenge to maternal calcium homoeostasis. The needs of the growing fetus have to be supplied but at the same time maternal bone and plasma calcium concentrations have to be maintained. If both these conditions are to be fulfilled changes in the secretion of calciumregulating hormones must occur.To determine the gestational changes in the secretion of calcium-regulating hormones we measured the plasma concentrations of calcitonin, parathyroid hormone, and the vitamin D metabolites 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-(OH),D) on four occasions during entirely normal pregnancies in a cross-sectional study. Previous studies either have been conducted only at the end of pregnancy or have been incomplete as important hormones have not been measured and details of the obstetric outcome have invariably been lacking. Thus the full interrelations of the calciumregulating hormones in normal pregn...

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Section: Methodsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 95%

Interrelations of calcium-regulating hormones during normal pregnancy.

Whitehead¹,

Lane²,

Young³

et al. 1981

BMJ

Self Cite

133

View full text Add to dashboard Cite

show abstract

“…Assay sensitivity was 10 pg/tube and intra-and inter-assay variations were 7.6% and 9.2% respectively. 25 hydroxyvitamin D. 25 (OH) D levels were measured using a competitive protein binding assay (43). The sensitivity of the method was SO pg/tube with intra-and inter-assay variations of 10.1 % and 13.2% respectively.…”

Section: Methodsmentioning

confidence: 99%

Effects in Postmenopausal Women of Natural and Synthetic Estrogens on Calcitonin and Calcium‐Regulating Hormone Secretion

Whitehead

Lane

Townsend

et al. 1982

Acta Obstet Gynecol Scand

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Abstract. The major function of calcitonin in man appears to be the prevention of excessive or unwanted bone resorption. There is a marked sex difference in circulating levels, with a relative deficiency in women. As calcitonin secretion in young women is known to be increased by estrogens, long periods of estrogen lack—such as the postmenopause—are possibly associated with a more pronounced calcitonin deficiency. This exaggerated deficiency could be an important factor in the pathogenesis of postmenopausal bone loss, especially as the latter is believed to be due to excessive bone resorption. We have studied the effects of three exogenous estrogens on the circulating levels in postmenopausal women of calcitonin, parathyroid hormone, the vitamin D metabolites 1,25 dihydroxyvitamin D and 25 hydroxyvitamin D, and calcium and phosphate. The most striking finding was a sharp rise in the plasma levels of calcitonin. Estrogens are known to prevent postmenopausal bone loss but the mechanism of action remains obscure. We suggest that the beneficial effects of estrogens could be mediated, at least in part, through control of calcitonin secretion. Thus calcitonin may prove effective in the prevention of postmenopausal bone loss and its role in the treatment of established osteoporosis warrants further evaluation.

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“…Antipyrine has recently been shown to produce a fall in circulating 25-0HD of about 60% in 12 subjects in whom hepatic drug oxidation was shown to be concomitantly increased. 20 We report the effect of short-term administration of the antibiotic rifampicin, a potent enzyme inducer, on vitamin D metabolism in humans.…”

mentioning

confidence: 99%

Rifampicin and vitamin D metabolism

Brodie

Boobis

Dollery

et al. 1980

Clin Pharmacol Ther

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A 2-wk course of rifampicin orally (600 mg/day) in 8 male subjects resulted in a consistent fall in plasma 25-hydroxycholecalciferol (25-OHD) levels of around 70%, accompanied by increased oxidation of antipyrine and 6 beta-hydroxycortisol (indicative of hepatic enzyme induction). Plasma levels of 1,25-dihydroxycholecalciferol, parathyroid hormone, and calcitonin were not altered. The fall in 25-OHD may represent the earliest lesion of drug-induced osteomalacia.

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Reduction of circulating 25‐hydroxyvitamin D by antipyrine.

Cited by 13 publications

References 25 publications

Interrelations of calcium-regulating hormones during normal pregnancy.

Interrelations of calcium-regulating hormones during normal pregnancy.

Effects in Postmenopausal Women of Natural and Synthetic Estrogens on Calcitonin and Calcium‐Regulating Hormone Secretion

Rifampicin and vitamin D metabolism

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