| 1. |
- Ahrén, B, et al.
(författare)
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Effects of minor increase in serum calcium on the immunoheterogeneity of parathyroid hormone in healthy subjects and in patients with primary hyperparathyroidism
- 1995
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Ingår i: Hormone Research. - 0301-0163. ; 43:6, s. 9-294
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Tidskriftsartikel (refereegranskat)abstract
- To study possible influences of a mild increase in serum-ionized calcium concentration that is seen during daily life on circulating parathyroid hormone (PTH) immunoheterogeneity, we used sequence-specific PTH assays to determine serum intact PTH, C-terminal PTH and N-terminal PTH following oral calcium (1.5 g) in healthy subjects (n = 7). This was also performed in patients with primary hyperparathyroidism (pHPT; n = 10) to see if their regulation of circulating PTH molecular forms is normal. Compared to healthy subjects, the patients were hypercalcemic (p < 0.05) and had higher levels of PTH in all three assays (p < 0.001). Following the oral calcium load, serum-ionized calcium increased by 0.08 +/- 0.03 mmol/l in the patients and by 0.07 +/- 0.03 mmol/l in the healthy subjects after 90 min, whereas serum intact PTH, C-terminal PTH and N-terminal PTH were reduced, both in the healthy subjects and in the patients. Suppression by calcium of both intact PTH and C-terminal PTH were impaired in the patients (p < 0.05 and p < 0.001), whereas suppression of N-terminal PTH was normal. Furthermore, the C/i and N/i ratios were higher at the highest calcium concentration achieved after calcium intake in the healthy subjects than in the basal state in the patients (p < 0.05), in spite of the larger degree of hypercalcemia in the latter (1.40 +/- 0.06 vs. 1.31 +/- 0.02 mmol/l; p < 0.05). Thus, (1) a minor increase in serum-ionized calcium that is seen during daily life alters the relative circulating concentrations of PTH versus its fragments; (2) the impaired sensitivity to calcium in pHPT is not evident for the suppression of N-terminal PTH, and (3) pHPT is accompanied by altered immunoheterogeneity of circulating PTH.
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| 6. |
- Andersson, Björn, 1977, et al.
(författare)
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Decrease in adiponectin levels correlates to growth response in growth hormone-treated children.
- 2009
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Ingår i: Hormone research. - : S. Karger AG. - 1423-0046 .- 0301-0163. ; 71:4, s. 213-8
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Tidskriftsartikel (refereegranskat)abstract
- Adiponectin is secreted by adipose tissue and circulates in human plasma at high levels. Decreased adiponectin levels are associated with insulin resistance and obesity. The aim of this study was to investigate whether changes in serum adiponectin levels are related to the growth response, insulin levels and insulin resistance during growth hormone (GH) treatment.
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| 12. |
- Bang, P, et al.
(författare)
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Free insulin-like growth factor I: are we hunting a ghost?
- 2001
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Ingår i: Hormone research. - : S. Karger AG. - 0301-0163. ; 5555 Suppl 2, s. 84-93
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Tidskriftsartikel (refereegranskat)abstract
- During the last decade, there has been an increasing number of publications reporting concentrations of free dissociable insulin-like growth factor I (IGF-I) in serum or plasma. The goal for attempting to measure free IGF-I in a serum sample in vitro has been to obtain information about the bioactivity of IGF-I in target tissues, and thus relate a measurable parameter to biological responses such as longitudinal growth or glucose disappearance rate. In this review, the serum free IGF-I approach is placed into a physiological perspective. In addition, methodological aspects are discussed and suggestions for the validation of free IGF-I assays are presented.
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| 20. |
- Berg, U, et al.
(författare)
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Exercise and circulating insulin-like growth factor I
- 2004
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Ingår i: Hormone research. - : S. Karger AG. - 0301-0163. ; 6262 Suppl 1, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Determinations of serum concentrations of total insulin-like growth factor I (tIGF-I) are important in the diagnosis, monitoring of treatment and safety evaluation of patients with growth disorders and/or metabolic disease. It is well established that tIGF-I status varies over time. Changes in tIGF-I levels in relation to an acute bout of exercise or repeated bouts, known as training, are likely to contribute to this variation. Serum tIGF-I has also been found to be of predictive value in growth prediction models employed before the start of growth hormone (GH) treatment. Furthermore, IGF-I generation tests have been suggested to be of value in the assessment of the growth response to GH administration in patients suspected of GH deficiency with or without some degree of GH insensitivity. This is discussed elsewhere in this issue. Recent progress in our understanding of growth hormone-dependent and -independent expression of the <i>IGF1</i> gene in skeletal muscle and the role of sufficient energy intake during training for muscle and liver generation of IGF-I raises important questions regarding their relative contribution to the circulating pool of IGF-I. The present review is focused on circulating levels of tIGF-I in relation to a single bout of exercise or to a period of training. In addition, the expression of IGF-I locally in muscle in response to these stimuli will be discussed.
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| 21. |
- Bergenfelz, A, et al.
(författare)
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Calcium metabolism after hemithyroidectomy
- 1993
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163 .- 1423-0046. ; 39:1-2, s. 56-60
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Tidskriftsartikel (refereegranskat)abstract
- It is not known whether thyroid surgery evokes changes in calcium metabolism. We therefore studied 6 patients operated upon with hemithyroidectomy for benign thyroid diseases, preoperatively and at 3 months and 1 year postoperatively. We measured changes in serum levels of intact parathyroid hormone (PTH), vitamin D metabolites, ionized calcium, phosphate, osteocalcin, thyroid hormones and bone density. Further, the dynamic function of the parathyroid glands was investigated by an oral calcium load test pre- and at 3 months postoperatively. At follow-up, all patients were euthyroid. During the oral calcium load, serum levels of intact PTH were reduced by the same degree before and after hemithyroidectomy, showing normal parathyroid function. Serum levels of 1,25-dihydroxyvitamin D declined from 86 +/- 16 to 57 +/- 4 pmol/l (p < 0.01) at 1 year after hemithyroidectomy, and serum levels of phosphate increased slightly from 0.96 +/- 0.08 to 1.06 +/- 0.08 mmol/l (p < 0.05), whereas serum levels of ionized calcium, intact PTH, osteocalcin and bone density did not change. Our results demonstrate that thyroid operation evokes changes in vitamin D metabolism in spite of normal parathyroid function.
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| 22. |
- Bergenfelz, A, et al.
(författare)
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Serum levels of thyrotropin are decreased by oral calcium in healthy subjects but not in patients with primary hyperparathyroidism
- 1994
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163 .- 1423-0046. ; 42:6, s. 7-273
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that calcium changes the set point of the pituitary thyroid feedback. It is not known, however, if small and slow changes of calcium and/or parathyroid hormone (PTH) within the physiological range influence the serum levels of thyrotropin (TSH) and thyroid hormones in healthy subjects or patients with primary hyperparathyroidism (pHPT). Nine healthy subjects and nine patients with pHPT were therefore investigated with an oral calcium load test. The patients were investigated before and 4 days after operation. During the test, serum levels of ionized calcium increased and serum levels of intact PTH decreased in both healthy subjects and patients pre- and postoperatively (p < 0.001). Furthermore, in patients, the suppressibility of serum levels of PTH by calcium increased postoperatively (p < 0.05). Serum levels of TSH decreased during the oral calcium load in healthy subjects (p < 0.01) but not in patients, whereas the serum levels of thyroid hormones did not change. It is concluded that oral calcium influences TSH secretion in healthy humans but not in patients with pHPT.
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| 23. |
- Bergenfelz, A, et al.
(författare)
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Serum osteocalcin levels do not change during rapidly induced hypercalcemia in healthy subjects
- 1992
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163 .- 1423-0046. ; 37:1-2, s. 29-32
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Tidskriftsartikel (refereegranskat)abstract
- Since osteocalcin has been suggested to play a role in calcium homeostasis, we investigated its serum levels in 6 healthy subjects during a rapid calcium infusion. Serum levels of intact parathyroid hormone (PTH), 25-hydroxyvitamin D [25-(OH) D3] and 1,25-dihydroxyvitamin D [1,25-(OH)2 D3] were also determined. The calcium infusion increased plasma-ionized calcium levels from 1.25 +/- 0.04 to 1.54 +/- 0.07 mmol/l at 30 min (p less than 0.05). Concomitantly, serum levels of intact PTH declined from 2.1 +/- 0.9 to 0.2 +/- 0.3 mmol/l (p less than 0.05). In contrast, serum osteocalcin levels did not change. Further, during calcium infusion, serum levels of 1,25-(OH)2 D3 decreased from 81 +/- 17 to 75 +/- 15 pmol/l (p less than 0.05) whereas serum levels of 25-(OH) D3 did not change. The results therefore suggest that calcium per se does not influence osteocalcin secretion.
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| 24. |
- Bergenfelz, A, et al.
(författare)
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Suppression by calcium of serum levels of intact parathyroid hormone in patients with primary hyperparathyroidism
- 1993
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163 .- 1423-0046. ; 39:3-4, s. 51-146
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Tidskriftsartikel (refereegranskat)abstract
- Primary hyperparathyroidism (pHPT) is associated with a right-shifted relation between parathyroid hormone (PTH) secretion and calcium. However, it is also possible that a decreased suppressibility of PTH secretion by calcium is important for maintaining hypercalcemia in pHPT. We therefore compared the suppression of serum levels of intact PTH induced by a 1.5-gram oral calcium load in patients with mild pHPT with that in healthy subjects. The calcemic response to the oral calcium load was the same in the two groups and did not correlate with the degree of PTH suppression or to serum levels of vitamin D metabolites. It was found that serum levels of intact PTH were less suppressed by the oral calcium load in patients than in healthy subjects (p < 0.01), but with a considerable overlap between the two groups. The suppression of serum levels of intact PTH was correlated both to baseline serum total calcium levels (r = -0.55; p < 0.05) and osteocalcin levels (r = -0.69; p < 0.05) in the patients, but no such correlations were seen in the controls. We conclude that patients with pHPT have a decreased suppressibility of PTH secretion by calcium. Although this reduced suppressibility could be important for maintaining hypercalcemia in some patients with pHPT, it does not aid in the differential diagnosis between patients with mild pHPT and healthy subjects.
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