Vitamin D status: effects on parathyroid hormone and 1,25-dihydroxyvitamin D in postmenopausal women

OBJECTIVE: Diurnal variations in plasma levels of 1,25-dihydroxyvitamin D (1,25(OH)(2)D) have previously only been investigated in young individuals, and these studies have failed to demonstrate a diurnal rhythm. We have studied whether plasma levels of 1,25(OH)(2)D and vitamin D-binding protein (DBP) vary in a diurnal rhythm in postmenopausal women. METHODS: Blood and urine were sampled with 2- and 4-h intervals in order to assess diurnal variations in plasma levels of 1,25(OH)(2)D, DBP and parathyroid hormone (PTH), as well as in plasma levels and urinary excretion rates of calcium and phosphate. Additionally, the free 1,25(OH)(2)D index was calculated (the molar ratio of 1,25(OH)(2)D to DBP). RESULTS: Plasma 1,25(OH)(2)D exhibited a diurnal rhythm (P<0.01) with a nadir in the morning (99+/-12 pmol/l), followed by a rapid increase to a plateau during the day (113+/-13 pmol/l, i.e. 14% above nadir level; P=0.005). A similar pattern of variation was found in plasma levels of DBP with peak levels 15% above nadir levels (P<0.01). The free 1,25(OH)(2)D index did not vary in a diurnal rhythm. PTH and plasma levels and urinary excretions of calcium and phosphate exhibited a diurnal pattern of variation. The diurnal rhythm of DBP was correlated with the rhythm of 1,25(OH)(2)D (r=0.47, P<0.01) and plasma albumin (r=0.76, P<0.01). Moreover, the rhythm of plasma calcium and PTH varied inversely (r=-0.36, P=0.02). CONCLUSIONS: With the disclosure of a diurnal rhythm of total plasma 1,25(OH)(2)D, all major hormones and minerals related to calcium homeostasis have now been shown to exhibit diurnal variations. In clinical studies, the diurnal variations of 1,25(OH)(2)D and DBP must be considered, i.e. blood sampling must be standardised according to the time of day.

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Vitamin D Status and Its Seasonal Variations and Association With Parathyroid Hormone Concentration in Healthy Women in Riga

Medicina ◽

10.3390/medicina49070051 ◽

2013 ◽

Vol 49 (7) ◽

pp. 51

Author(s):

Aivars Lejnieks ◽

Anda Slaidina ◽

Agnis Zvaigzne ◽

Una Soboleva ◽

Gulsena Eivazova ◽

...

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Postmenopausal Women ◽

Seasonal Variations ◽

Threshold Level ◽

Vitamin D Supplementation ◽

Reproductive Age ◽

Vitamin D Status ◽

Healthy Women ◽

Vitamin D Supplements

The aim of the study was to describe the vitamin D status and its seasonal variations in women living in Riga, Latvia, to examine an association between the concentrations of plasma 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH), and to determine the threshold for plasma 25(OH)D above which there is no further suppression of PTH. Material and Methods. The data of 189 healthy Caucasian women were analyzed. The serum levels of 25(OH)D, PTH, and phosphorus were measured twice a year. All the participants were divided into 3 groups according to vitamin D supplementation and the reproductive status. Results. The overall mean level of 25(OH)D was 32.8 ng/mL with significantly lower levels being in winter when compared with those in summer (28.2 ng/mL vs. 37.5 ng/mL, respectively; P<0.05). PTH was negatively associated with 25(OH)D. A threshold level of plasma 25(OH)D above which no further suppression of PTH occurred was found to be 38 ng/mL. Postmenopausal women not taking vitamin D supplements and without exposure to sunlight had 25(OH)D deficiency in winter and summer (92% and 88%, respectively). The most significant seasonal fluctuations were seen in the women of the reproductive age not taking vitamin D supplements and without exposure to sunlight, of which 47% had 25(OH)D deficiency in summer and 69% in winter. Conclusions. An optimal concentration of 25(OH)D was found to be 38 ng/mL. According to this definition, 70.4% of all the healthy women were classified as vitamin D deficient in winter and 59.8% in summer. The highest proportion of vitamin D deficient individuals was found in the group representing the postmenopausal women not taking vitamin D supplements.

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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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IDIOPATHIC INFANTILE HYPERCALCEMIA . DESCRIPTION OF CLINICAL CASES AND REVIEW.

Problems of Endocrinology ◽

10.14341/probl201763142-48 ◽

2017 ◽

Vol 63 (1) ◽

pp. 51-57

Author(s):

Yulia V. Tikhonovich ◽

Anna A. Kolodkina ◽

Kristina S. Kulikova ◽

Yulia Yu. Golubkina ◽

Natalia Yu. Kalinchenko ◽

...

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Family Counseling ◽

Compound Heterozygous ◽

Loss Of Function ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Low Calcium Diet ◽

Idiopathic Infantile Hypercalcemia ◽

Vitamin D Supplements

Vitamin D plays a central role in calcium homeostasis. Impaired degradation of 1,25-dihydroxyvitamin D due to loss-of-function mutations in CYP24A1 leads to significant hypercalcemia, hypercalciuria, suppressed level of parathyroid hormone (PTH), nephrocalcinosis and nephrolithiasis. This condition has been called Idiopathic infantile hypercalcemia. Treatment includes low calcium diet, rehydration, furosemid, avoidance of vitamin D supplements and sun protection. In severe cases glucocorticoids, ketoconazole, bisphosphonates and hemodiafiltration may be used. Early diagnosis of the disease allows to develop an individual plan for managing these patients to prevent the formation of kidney disease, to conduct a genetic family counseling. Here, we describe the cohort of patients (3 children, 2 adults) with significant hypercalcemia due to homo- and compound heterozygous mutations in CYP24A1, describe the main clinical and laboratory characteristics, diagnosis, principles and foundations of the management of patients with this pathology.

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Effects of estrogen on circulating "free" and total 1,25-dihydroxyvitamin D and on the parathyroid-vitamin D axis in postmenopausal women.

Journal of Clinical Investigation ◽

10.1172/jci113915 ◽

1989 ◽

Vol 83 (2) ◽

pp. 537-542 ◽

Cited By ~ 110

Author(s):

C Cheema ◽

B F Grant ◽

R Marcus

Keyword(s):

Vitamin D ◽

Postmenopausal Women ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D

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90300684 Effects of estrogen on daylong circulating calcium, phosphorus, 1,25-dihydroxyvitamin D, and parathyroid hormone in postmenopausal women

Maturitas ◽

10.1016/0378-5122(91)90121-6 ◽

1991 ◽

Vol 13 (2) ◽

pp. 172

Author(s):

E Packer ◽

L Holloway ◽

K Newhall ◽

G Kanwar ◽

G Butterfield ◽

...

Keyword(s):

Parathyroid Hormone ◽

Postmenopausal Women ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Calcium Phosphorus

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Effect of Parathyroid Hormone on cAMP and 1,25-Dihydroxyvitamin D Formation and Renal Handling of Phosphate in Vitamin D-Dependent Rickets

PEDIATRICS ◽

10.1542/peds.71.1.59 ◽

1983 ◽

Vol 71 (1) ◽

pp. 59-63

Author(s):

Dagfinn Aarskog ◽

Lage Aksnes ◽

Trond Markestad

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Serum Concentration ◽

Urinary Excretion ◽

Serum Levels ◽

Renal Handling ◽

Hydroxyvitamin D ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Control Subjects

Studies were carried out to compare the effects of parathyroid extract (PTE) on the serum concentration of 1,25-dihydroxyvitamin D (1,25[OH]2D), 24,25-dihydroxyvitamin D (24,25[OH]2D), 25,26-dihydroxy vitamin D (25,26[OH]2D) and cAMP, and the urinary excretion of calcium, phosphorus, and cAMP in two normal adult subjects, and in a girl with vitamin D-dependent rickets. The concentration of 1,25[OH]2D was markedly decreased even when she was receiving a daily dose of 25,000 IU of ergocalciferol. PTE infusion resulted in a prompt and distinct increase in the serum levels and the urinary excretion of cAMP in the patient and control subjects. In the control subjects the serum concentration of 1,25[OH]2D increased after the PTE infusion, whereas there was no response in the patient with vitamin D-dependent rickets. The two other dihydroxylated metabolites of vitamin D showed no consistent response to the PTE infusion in the control subjects or the patient. The patient showed no phosphaturic response to PTE while she was receiving high-dosage ergocalciferol treatment. By contrast, when the patient was re-studied after therapy with lα-hydroxyvitamin D, PTE infusion resulted in an increase in urinary phosphate excretion. These findings might lend support for the notion that 1,25[OH]2D has an effect on tubular phosphate resorption and has a permissive role in the phosphaturic effect of parathyroid hormone. The present findings also confirm that the formation of 1,25[OH]2D is impaired in vitamin D-dependent rickets and indicate that the renal 25-hydroxyvitamin D-lα-hydroxylase is unresponsive to the stimulatory effect of parathyroid hormone in this condition.

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Sturzrisiko bei älteren Menschen

Osteologie/Osteology ◽

10.1055/s-0037-1619859 ◽

2008 ◽

Vol 17 (03) ◽

pp. 135-141

Author(s):

S. Scharla

Keyword(s):

Vitamin D ◽

Vitamin D Status ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D

ZusammenfassungVitamin-D-Mangel tritt bei älteren Menschen häufig auf. Da Vitamin-D-Metaboliten einen Einfluss auf die Muskelfunktion haben, ist ein Vitamin-D-Mangel mit einem erhöhten Sturzrisiko assoziiert. In älteren Populationen mit Vitamin-D-Mangel kann das Sturzrisiko durch die Behandlung mit nativem Vitamin D verringert werden. Bei Studienteilnehmern mit ausreichendem Vitamin-D-Status wurde jedoch kein konsistenter Therapieeffekt von Vitamin D beobachtet. Die Therapie mit 1α-hydroxylierten Vitamin D-Metaboliten (Calcitriol und Alfacalcidol) senkte in kontrollierten Studien das Sturzrisiko. Bereits eine mäßiggradige Abnahme der Nierenfunktion (Kreatinin-Clearance <65 ml/min) erhöht das Sturzrisiko, wahrscheinlich infolge der reduzierten Aktivität der renalen 1α-Hydroxylase und einer Verringerung der 1,25-Dihydroxyvitamin-D-Konzentration im Serum. Eine Therapie mit 1α-hydroxylierten Vitamin-D-Metaboliten senkt bei Patienten mit eingeschränkter Nierenfunktion das Sturzrisiko.

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Adaptation to dietary calcium and phosphorus restriction changes with age in the rat

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1980.239.5.e322 ◽

1980 ◽

Vol 239 (5) ◽

pp. E322-E327 ◽

Cited By ~ 4

Author(s):

H. J. Armbrecht ◽

T. V. Zenser ◽

C. J. Gross ◽

B. B. Davis

Keyword(s):

Vitamin D ◽

Parathyroid Hormone ◽

Active Transport ◽

Intestinal Adaptation ◽

Tubular Reabsorption ◽

Dihydroxyvitamin D ◽

1,25 Dihydroxyvitamin D ◽

Calcium And Phosphorus ◽

F344 Rats ◽

Male F344 Rats

The purpose of this study was to characterize the changes that take place in adaptation to chronic calcium (Ca) or phosphorus (P) restriction with age. Adaptation in male F344 rats aged 1.5, 3, 12, and 18 mo was studied by feeding rats either a low-Ca diet, a low-P diet, or a high-Ca-P diet for 14 days. Plasma Ca remained relatively constant with age, but plasma P markedly decreased between 3 and 12 mo regardless of diet. Intestinal adaptation was determined by measuring the active transport of Ca by the intestine and by measuring the production of vitamin D-dependent calcium-binder protein. There was significant intestinal adaptation to Ca or P restriction at 1.5 mo, but there was none thereafter because Ca transport declined rapidly with age regardless of diet. The kidney adapted to the low-P diet by significantly reducing P excretion at all ages. In rats on a low-P diet, there was an increase in urinary P, which was due to a decrease in the tubular reabsorption of P and a decrease in urinary Ca with age. These changes in adaptation may reflect a decrease in serum 1,25-dihydroxyvitamin D levels and an increase in parathyroid hormone levels with age.

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