Home About us Contact
|
Home About us Contact | ||
|
|
||
PTH Concentrations (pth + concentration)
Selected AbstractsAkt2/PKB,-sensitive regulation of renal phosphate transportACTA PHYSIOLOGICA, Issue 1 2010D. S. Kempe Abstract Aim:, The protein kinase B (PKB)/Akt is known to stimulate the cellular uptake of glucose and amino acids. The kinase is expressed in proximal renal tubules. The present study explored the influence of Akt/PKB on renal tubular phosphate transport. Methods:, The renal phosphate transporter NaPi-IIa was expressed in Xenopus oocytes with or without PKB/Akt and Na+ phosphate cotransport determined using dual electrode voltage clamp. Renal phosphate excretion was determined in Akt2/PKB, knockout mice (akt2,/,) and corresponding wild-type mice (akt2+/+). Transporter protein abundance was determined using Western blotting and phosphate transport by 32P uptake into brush border membrane vesicles. Results:, The phosphate-induced current in NaPi-IIa-expressing Xenopus oocytes was significantly increased by the coexpression of Akt/PKB. Phosphate excretion [,mol per 24 h per g BW] was higher by 91% in akt2,/, than in akt2+/+ mice. The phosphaturia of akt2,/, mice occurred despite normal transport activity and expression of the renal phosphate transporters NaPi-IIa, NaPi-IIc and Pit2 in the brush border membrane, a significantly decreased plasma PTH concentration (by 46%) and a significantly enhanced plasma 1,25-dihydroxyvitamin D3 concentration (by 46%). Moreover, fractional renal Ca2+ excretion was significantly enhanced (by 53%) and bone density significantly reduced (by 11%) in akt2,/, mice. Conclusions:, Akt2/PKB, plays a role in the acute regulation of renal phosphate transport and thus contributes to the maintenance of phosphate balance and adequate mineralization of bone. [source] Wintertime Vitamin D Supplementation Inhibits Seasonal Variation of Calcitropic Hormones and Maintains Bone Turnover in Healthy Men,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2009Heli T Viljakainen Abstract Vitamin D is suggested to have a role in the coupling of bone resorption and formation. Compared with women, men are believed to have more stable bone remodeling, and thus, are considered less susceptible to the seasonal variation of calcitropic hormones. We examined whether seasonal variation exists in calcitropic hormones, bone remodeling markers, and BMD in healthy men. Furthermore, we determined which vitamin D intake is required to prevent this variation. Subjects (N = 48) were healthy white men 21,49 yr of age from the Helsinki area with a mean habitual dietary intake of vitamin D of 6.6 ± 5.1 (SD) ,g/d. This was a 6-mo double-blinded vitamin D intervention study, in which subjects were allocated to three groups of 20 ,g (800 IU), 10 ,g (400 IU), or placebo. Fasting blood samplings were collected six times for analyses of serum (S-)25(OH)D, iPTH, bone-specific alkaline phosphatase (BALP), and TRACP. Radial volumetric BMD (vBMD) was measured at the beginning and end of the study with pQCT. Wintertime variation was noted in S-25(OH)D, S-PTH, and S-TRACP (p < 0.001, p = 0.012, and p < 0.05, respectively) but not in S-BALP or vBMD in the placebo group. Supplementation inhibited the winter elevation of PTH (p = 0.035), decreased the S-BALP concentration (p < 0.05), but benefited cortical BMD (p = 0.09) only slightly. Healthy men are exposed to wintertime decrease in vitamin D status that impacts PTH concentration. Vitamin D supplementation improved vitamin D status and inhibited the winter elevation of PTH and also decreased BALP concentration. The ratio of TRACP to BALP shows the coupling of bone remodeling in a robust way. A stable ratio was observed among those retaining a stable PTH throughout the study. A daily intake of vitamin D in the range of 17.5,20 ,g (700,800 IU) seems to be required to prevent winter seasonal increases in PTH and maintain stable bone turnover in young, healthy white men. [source] Hyperparathyroidism in dogs with hyperadrenocorticismJOURNAL OF SMALL ANIMAL PRACTICE, Issue 11 2005I. K. Ramsey Objectives: To assess the effect of canine hyperadrenocorticism (HAC) on parathyroid hormone (PTH), phosphate and calcium concentrations. Methods: PTH concentrations and routine biochemical parameters were measured in 68 dogs with HAC. Ionised calcium was measured in 28 of these dogs. The results obtained were compared with an age- and weight-matched group of 20 hospital patients that did not show signs of HAC. Results: There were significant differences between the PTH, phosphate, alkaline phosphatase, creatinine and albumin concentrations between the two groups. Total and ionised calcium concentrations were not significantly different. Most of the dogs (92 per cent) with HAC had PTH concentrations that were greater than the reference range (10 to 60 pg/ml), and in 23 dogs they were greater than 180 pg/ml. There were significant positive correlations between the PTH and basal cortisol, post-adrenocorticotropic hormone (ACTH) cortisol and alkaline phosphatase concentrations, and also the phosphate and post-ACTH cortisol concentrations. Clinical Significance: Adrenal secondary hyperparathyroidism is a cause of increased PTH concentrations and may be associated with abnormalities in calcium and phosphate metabolism in dogs with HAC. The findings of this study could explain why canine HAC may cause clinical signs such as calcinosis cutis that are associated with altered calcium metabolism. [source] Canine hyperadrenocorticism: effects of trilostane on parathyroid hormone, calcium and phosphate concentrationsJOURNAL OF SMALL ANIMAL PRACTICE, Issue 11 2005A. J. Tebb Objectives: To determine the effects of treating canine hyperadrenocorticism (HAC) on parathyroid hormone (PTH), calcium and phosphate concentrations in dogs. Methods: Serum calcium, phosphate and PTH concentrations were analysed in 22 dogs with HAC before treatment with trilostane and at a median of 210 days after commencing treatment. Pretreatment data were compared with data from an age- and weight-matched group of hospitalised patients, and post-treatment data were compared with pretreatment data. Results: PTH and phosphate concentrations were significantly higher in dogs with HAC compared with control dogs. PTH concentrations reduced significantly with treatment, such that there was no longer difference between the HAC and control groups. Phosphate concentrations also reduced significantly with treatment but there was still a significant difference between those in dogs with HAC and control dogs. Despite no significant difference between calcium concentrations in the pretreatment HAC and control groups, calcium concentrations increased significantly with treatment. Clinical Significance: These results show that adrenal secondary hyperparathyroidism resolves with treatment and suggest that increased calcium and phosphate levels have a role in its pathogenesis. [source] Effect of treatment with depot somatostatin analogue octreotide on primary hyperparathyroidism (PHP) in multiple endocrine neoplasia type 1 (MEN1) patientsCLINICAL ENDOCRINOLOGY, Issue 5 2008Antongiulio Faggiano Summary Background, In patients with multiple endocrine neoplasia type 1 (MEN1), expression of somatostatin receptor (SST) in parathyroid adenomas and effectiveness of therapy with somatostatin analogues on primary hyperparathyroidism (PHP) have been scarcely investigated. Objective, To evaluate the effects of depot long acting octreotide (OCT-LAR) in patients with MEN1-related PHP. Patients, Eight patients with a genetically confirmed MEN1, presenting both PHP and duodeno-pancreatic neuroendocrine tumours (NET), were enrolled. Design, The initial treatment was OCT-LAR 30 mg every 4 weeks. This therapy was established to stabilize the duodeno-pancreatic NET before to perform parathyroidectomy for PHP. Before OCT-LAR therapy, a SST scintigraphy was performed in all patients. SST subtype 2A immunohistochemistry was performed on parathyroid tumour samples from three patients undergone parathyroidectomy after OCT-LAR therapy. Measurements, Serum concentrations of PTH, calcium and phosphorus as well as the 24-h urine calcium : creatinine ratio and the renal threshold phosphate concentration were evaluated before and after OCT-LAR. Results, After OCT-LAR therapy, hypercalcaemia and hypercalciuria normalized in 75% and 62·5% of patients, respectively, and serum phosphorus and renal threshold phosphate significantly increased. Serum PTH concentrations significantly decreased in all patients and normalized in two of them. SST subtype 2A immunostaining was found in all parathyroid adenomas investigated, while SST scintigraphy showed a positive parathyroid tumour uptake in three of eight patients (37·5%). Conclusion, Six months of OCT-LAR therapy controlled hypercalcaemia and hypercalciuria in two-thirds of patients with MEN1-related PHP. Direct OCT-LAR effects mediated by binding to SST expression on parathyroid tumour cells are likely the main mechanism to explain the activity of this compound on calcium and phosphorus abnormalities in MEN1 PHP. [source] Impaired GH secretion to provocative stimuli in two families with hypocalciuric hypercalcaemiaCLINICAL ENDOCRINOLOGY, Issue 5 2003Elisabetta Cecconi Summary objective, To determine whether hypercalcemia per se might be responsible for an impairment in GH secretion. design, Prospective study. patients, Six subjects of two unrelated families with familial hypocalciuric hypercalcaemia (FHH), an autosomal dominant disorder due to inactivating mutations in the calcium receptor gene, leading to an increase in serum calcium levels and inappropriately normal serum PTH concentrations. Forty normal subjects, matched for sex and age served as controls. measurements, Serum GH concentrations were measured after GHRH-Arginine (GHRH-Arg) stimulation test; serum IGF-I, ACTH, cortisol, FT4, FT3, TSH, PRL, LH, FSH levels were measured under basal conditions. results, All subjects (two male, four female, age range 24,74 years) had increased serum ionized calcium levels (range 1·36,1·56 mmol/l) and five of six patients had normal PTH levels (range for all patients was 14,68 ng/l). Basal serum GH concentrations ranged from 0·1 to 7·0 µg/l. Mean serum GH secretory peak after GHRH-Arg stimulation test was reduced in five subjects (mean 9·3 ± 3·6 µg/l, P < 0·006 vs. Controls, mean 67·0 ± 44·0 µg/l, cut-off, 16·0 µg/l) and normal in one subject (38·7 µg/l). However, serum IGF-I levels were reduced only in two patients (29 and 57 µg/l) and normal in four subjects (range 127,208 µg/l). The basal secretion of the other anterior pituitary hormones was within their normal ranges. conclusions, The results of the present study support the concept that elevated serum calcium levels impair GH secretion. However, the clinical relevance of GH deficiency in FHH remains to be elucidated. [source] | ||||||||||