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Decreased levels of ionized calcium one year after hemithyroidectomy: importance of reduced thyroid hormones

Lindblom, Pia LU ; Valdemarsson, Stig LU ; Lindergård, Birger LU ; Westerdahl, Johan LU and Bergenfelz, Anders LU (2001) In Hormone Research 55(2). p.81-87
Abstract
BACKGROUND: Previously we have found reduced levels of total serum calcium and 1,25(OH)2D3 despite an unaltered stimulated parathyroid hormone (PTH) secretion 1 year after hemithyroidectomy. The present study was undertaken to elucidate the possible relationship between calcium homeostasis, thyroid hormones and bone resorption in a group of 45 consecutive patients subjected to hemithyroidectomy because of a solitary nodule. All patients had free T4 and T3 levels within normal range preoperatively. METHODS: Thyroid hormones, bone mineral and biochemical variables known to reflect calcium homeostasis were studied. Patients were divided into three separate groups depending on their pre- and postoperative thyroid hormone status. RESULTS: One... (More)
BACKGROUND: Previously we have found reduced levels of total serum calcium and 1,25(OH)2D3 despite an unaltered stimulated parathyroid hormone (PTH) secretion 1 year after hemithyroidectomy. The present study was undertaken to elucidate the possible relationship between calcium homeostasis, thyroid hormones and bone resorption in a group of 45 consecutive patients subjected to hemithyroidectomy because of a solitary nodule. All patients had free T4 and T3 levels within normal range preoperatively. METHODS: Thyroid hormones, bone mineral and biochemical variables known to reflect calcium homeostasis were studied. Patients were divided into three separate groups depending on their pre- and postoperative thyroid hormone status. RESULTS: One year postoperatively, serum levels of free T4 were decreased and that of thyrotropin (TSH) increased in the entire group of patients. The concentration of ionized calcium was reduced from 1.25 +/- 0.05 to 1.22 +/- 0.04 (p < 0.001) despite an unaltered PTH value (2.8 +/- 1.0 vs. 3.1 +/- 1.5, p = 0.50). A significant reduction in C-terminal telopeptide type 1 collagen (1CTP) indicated decreased bone resorption 1 year after surgery (p < 0.05). Subgroup analysis showed that a reduction in ionized calcium was seen only among patients with a postoperative decrease in free T4. Patients with subclinical hyperthyroidism preoperatively presented the lowest postoperative levels of ionized calcium, significantly reduced levels of 1CTP and increased levels of phosphate and creatinine. Multiple linear regression analysis showed that age (p < 0.05) and postoperatively changed serum levels of TSH (p < 0.05), creatinine (p < 0.05), phosphate (p < 0.001) and FT4 (p < 0.01) were independently associated with altered levels of ionized calcium. CONCLUSION: We conclude that the reduction in ionized calcium 1 year after hemithyroidectomy was not due to PTH deficiency. Instead our results suggest that the reduced effects of thyroid hormones on bone and kidney function is essential. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Hemithyroidectomy, Unilateral thyroidectomy, Ionized calcium, Reduced thyroid hormones, Calcium homeostasis, Bone density
in
Hormone Research
volume
55
issue
2
pages
81 - 87
publisher
Karger
external identifiers
  • pmid:11509864
  • scopus:0034880285
ISSN
0301-0163
DOI
10.1159/000049975
language
English
LU publication?
yes
id
2019f39d-a660-45ec-94ec-db7978c2f975 (old id 1122824)
date added to LUP
2008-07-03 11:56:49
date last changed
2018-01-07 08:38:22
@article{2019f39d-a660-45ec-94ec-db7978c2f975,
  abstract     = {BACKGROUND: Previously we have found reduced levels of total serum calcium and 1,25(OH)2D3 despite an unaltered stimulated parathyroid hormone (PTH) secretion 1 year after hemithyroidectomy. The present study was undertaken to elucidate the possible relationship between calcium homeostasis, thyroid hormones and bone resorption in a group of 45 consecutive patients subjected to hemithyroidectomy because of a solitary nodule. All patients had free T4 and T3 levels within normal range preoperatively. METHODS: Thyroid hormones, bone mineral and biochemical variables known to reflect calcium homeostasis were studied. Patients were divided into three separate groups depending on their pre- and postoperative thyroid hormone status. RESULTS: One year postoperatively, serum levels of free T4 were decreased and that of thyrotropin (TSH) increased in the entire group of patients. The concentration of ionized calcium was reduced from 1.25 +/- 0.05 to 1.22 +/- 0.04 (p &lt; 0.001) despite an unaltered PTH value (2.8 +/- 1.0 vs. 3.1 +/- 1.5, p = 0.50). A significant reduction in C-terminal telopeptide type 1 collagen (1CTP) indicated decreased bone resorption 1 year after surgery (p &lt; 0.05). Subgroup analysis showed that a reduction in ionized calcium was seen only among patients with a postoperative decrease in free T4. Patients with subclinical hyperthyroidism preoperatively presented the lowest postoperative levels of ionized calcium, significantly reduced levels of 1CTP and increased levels of phosphate and creatinine. Multiple linear regression analysis showed that age (p &lt; 0.05) and postoperatively changed serum levels of TSH (p &lt; 0.05), creatinine (p &lt; 0.05), phosphate (p &lt; 0.001) and FT4 (p &lt; 0.01) were independently associated with altered levels of ionized calcium. CONCLUSION: We conclude that the reduction in ionized calcium 1 year after hemithyroidectomy was not due to PTH deficiency. Instead our results suggest that the reduced effects of thyroid hormones on bone and kidney function is essential.},
  author       = {Lindblom, Pia and Valdemarsson, Stig and Lindergård, Birger and Westerdahl, Johan and Bergenfelz, Anders},
  issn         = {0301-0163},
  keyword      = {Hemithyroidectomy,Unilateral thyroidectomy,Ionized calcium,Reduced thyroid hormones,Calcium homeostasis,Bone density},
  language     = {eng},
  number       = {2},
  pages        = {81--87},
  publisher    = {Karger},
  series       = {Hormone Research},
  title        = {Decreased levels of ionized calcium one year after hemithyroidectomy: importance of reduced thyroid hormones},
  url          = {http://dx.doi.org/10.1159/000049975},
  volume       = {55},
  year         = {2001},
}