Thyroid hormone independent associations between serum TSH levels and indicators of bone turnover in cured patients with differentiated thyroid carcinoma.
OBJECTIVE
It has been proposed that TSH has thyroid hormone-independent effects on bone mineral density (BMD) and bone metabolism. This concept is still controversial and has not been studied in human subjects in detail. We addressed this question by studying relationships between serum TSH concentration and indicators of bone turnover, after controlling for triiodothyronine (T(3)), free thyroxine (FT(4)), and non-thyroid factors relevant to BMD and bone metabolism. We also studied the contribution of the TSH receptor (TSHR)-Asp727Glu polymorphism to these relationships.


METHODS
We performed a cross-sectional study with 148 patients, who had been thyroidectomized for differentiated thyroid carcinoma.


METHODS
We measured BMD of the femoral neck and lumbar spine. FT(4), T(3), TSH, bone-specific alkaline phosphatase, procollagen type 1 aminoterminal propeptide levels, C-cross-linking terminal telopeptide of type I collagen, and urinary N-telopeptide of collagen cross-links were measured. Genotypes of the TSHR-Asp727Glu polymorphism were determined by Taqman assay.


RESULTS
We found a significant, inverse correlation between serum TSH levels and indicators of bone turnover, which was independent of serum FT(4) and T(3) levels as well as other parameters influencing bone metabolism. We found that carriers of the TSHR-Asp727Glu polymorphism had an 8.1% higher femoral neck BMD, which was, however, no longer significant after adjusting for body mass index.


CONCLUSIONS
We conclude that in this group of patients, serum TSH was related to indicators of bone remodeling independently of thyroid hormone levels. This may point to a functional role of the TSHR in bone in humans. Further research into this mechanism needs to be performed.
Heemstra
Karen A
KA
Department of Endocrinology and Metabolism, C4-R, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
van der Deure
Wendy M
WM
Peeters
Robin P
RP
Hamdy
Neveen A
NA
Stokkel
Marcel P
MP
Corssmit
Eleonora P
EP
Romijn
Johannes A
JA
Visser
Theo J
TJ
Smit
Johannes W
JW
D015502:Absorptiometry, Photon; D000328:Adult; D000818:Animals; D015519:Bone Density; D001842:Bone and Bones; D003430:Cross-Sectional Studies; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D011989:Receptors, Thyrotropin / Q000235:genetics / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D011989:Receptors, Thyrotropin; D013963:Thyroid Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine