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- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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