Bone turnover in hyperthyroidism before and after thyrostatic management

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Association of decreased muscle mass with reduced bone mineral density in patients with Graves' disease

AIM

This study aimed to determine the association of decreased muscle mass with reduced bone mineral density in patients with Graves' disease.

METHODS

A total of 758 patients with Graves' disease at diagnosis (mean age 41.2 years) were enrolled for a cross-sectional study; of these, 287 were enrolled for a cohort study with a median follow-up of 24 months. Meanwhile, 1164 age- and sex-matched healthy controls were recruited. All participants underwent dual-energy x-ray absorptiometry and muscle mass index (ASMI) measurements. The changes in ASMI and bone mineral density (BMD) were calculated from the measurements made at a gap of 2 years.

RESULTS

The BMD of patients with Graves' disease was still significantly lower after normalizing serum thyroid hormone levels compared with that of healthy controls. ASMI positively correlated with BMD in patients with Graves' disease (lumbar BMD, r = 0.210; femoral neck BMD, r = 0.259; hip BMD, r = 0.235; P < 0.001), and this relationship persisted after successful anti-thyroid therapy (lumbar BMD, r = 0.169; femoral neck BMD, r = 0.281; hip BMD, r = 0.394; P < 0.001). Low muscle mass was associated with low BMD (OR, 1.436; 95% CI, 1.026-2.010). Improving the muscle mass led to changes in the bone mass of the femoral neck (OR, 0.420; 95% CI, 0.194-0.911) and hip (OR, 0.217; 95% CI, 0.092-0.511) during the follow-up. However, this phenomenon was not observed in lumbar and bone turnover markers.

CONCLUSIONS

The recovery of bone mass might be related to the recovery of the muscle mass. Patients with Graves' disease should be helped to regain their muscle mass and thus accelerate the recovery of bone mass while administering anti-thyroid therapy.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

Current concepts in odontohypophosphatasia form of hypophosphatasia and report of two cases

BACKGROUND

Hypophosphatasia is a rare inherited disease derived from mutations in tissue non-specific alkaline phosphatase genes, with typical oral symptoms including short root anomaly and dysplasia of dentin or cementum.

CASE PRESENTATION

Two young female patients presented with short root anomaly with a history of premature loss of deciduous and/or permanent teeth. The laboratory and imaging investigations were performed. One case was diagnosed as odontohypophosphatasia concurrent with hyperthyroidism, the other was odontohypophosphatasia concurrent with multiple radicular cysts.

CONCLUSION

This report presents two cases of odontohypophosphatasia, a rare disease which is difficult to be diagnosed, and highlights that the history of premature loss of deciduous and/or permanent teeth, oral manifestation and laboratory tests are crucial for clinical diagnosis.

Calcium homeostasis in thyroid disease in dogs and cats

Hyperthyroidism is the most common endocrine disorder of cats, and hypothyroidism is the most common endocrine disorder of dogs. Little is known regarding the effects of hyperthyroidism, hypothyroidism, or treatment of these disorders on calcium metabolism in the dog or cat, however, especially any potential effects on bone. With better diagnostic tools, better treatments, and increased longevity of pets, the clinical impact of thyroid disorders on calcium metabolism and bone may be uncovered.

The adaptation and relationship of FGF-23 to changes in mineral metabolism in Graves' disease

OBJECTIVE

The aim of this study was to observe the changes in bone and mineral metabolism and to confirm the regulation of fibroblast growth factor-23 (FGF-23) in untreated Graves' disease.

PATIENTS AND MEASUREMENTS

The study comprised 39 patients, with or without Graves' disease. The Graves' disease group was made up of 21 newly diagnosed patients, enrolled before starting treatment. Their disease was determined by biochemical and radiological means. The control group was composed of 18 people who were proven to be euthyroid without any diseases affecting bone and mineral metabolism. FGF-23, calcium, phosphate, PTH, 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] levels and bone turnover markers were compared between these groups.

RESULTS

Serum calcium and phosphate, plasma FGF-23 and free T4 were significantly higher in the Graves' disease group than in the healthy control group (P < 0.05). The bone turnover markers serum osteocalcin and C-terminal cross-linked telopeptide of type 1 collagen (s-CTx) were also significantly elevated in the Graves' disease group, and had a positive correlation with free T4 levels. However, there was no significant decrease in PTH and 1,25(OH)2D in the Graves' disease group. Plasma levels of FGF-23 exhibited a positive correlation with serum phosphate levels and with free T4 levels (P < 0.05).

CONCLUSIONS

These findings suggest that FGF-23 is physiologically related to serum phosphate homeostasis, as indicated indirectly by the changes in bone and mineral metabolism, in untreated Graves' disease.

Serum osteoprotegerin and soluble receptor activator of nuclear factor kappaB ligand levels in patients with a history of differentiated thyroid carcinoma: a case-controlled cohort study

Overt hyperthyroidism is associated with changes in bone metabolism, whereas the effect of levothyroxine (L-T4) load in patients with differentiated thyroid carcinoma (DTC) is controversial. The aim of our study was to evaluate osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kappaB ligand (RANK-L) in patients with DTC with suppressed endogenous thyrotropin due to L-T4 regimen. A cohort of 80 subjects with DTC (68 women and 12 men; age range, 27-81 years) was studied. A cohort of 55 subjects with a history of partial or total surgery for nonmalignant thyroid pathology served as a control group. Groups were matched for sex, age, and body mass index. Per-week dosage of L-T4 was significantly higher in patients with DTC than in controls (P < .001). More elevated free T(4) concentrations (P < .001) and more suppressed thyrotropin and thyroglobulin levels (P < .001) were found in subjects with DTC than in controls. No difference in serum or urinary parameters related to bone metabolism or dual-energy x-ray absorptiometry was noted between the groups. Overall, OPG levels were similar in both groups but were significantly (P = .03) lower in postmenopausal women with DTC than in postmenopausal control women. Only control women showed lower OPG levels in premenopausal than in postmenopausal (P = .002) conditions. Overall, RANK-L levels were significantly higher (P = .03) in subjects with DTC than in controls. In both groups, OPG and RANK-L levels were unrelated to each other. A significant positive correlation was seen between OPG levels and age in both subjects with DTC (P < .001) and controls (P < .001). Serum RANK-L correlated negatively with age in subjects with DTC (P = .05). Although there were several differences in L-T4 dosages, OPG and RANK-L levels were similar in patients with a history of DTC and those with a history of nonmalignant thyroid diseases. The correlation between circulating OPG and RANK-L levels was not significant. The increase in OPG with age indicates its protective role in bone loss. The cause of bone loss after long-term L-T4 load will be more extensively studied.

Recombinant human TSH modulates in vivo C-telopeptides of type-1 collagen and bone alkaline phosphatase, but not osteoprotegerin production in postmenopausal women monitored for differentiated thyroid carcinoma

In women monitored for thyroid carcinoma, short-term stimulation with rhTSH induced an acute decrease in serum C-telopeptides of type-1 collagen and an increase in serum BALP levels without any effect on OPG production. The inhibitory effect of TSH on bone resorption occurred only in postmenopausal women who showed low BMD and a high bone turnover rate as an effect of L-thyroxine suppressive therapy.

INTRODUCTION

It has been recently shown that thyrotropin (TSH) has an inhibitory activity on skeletal remodeling in in vitro conditions. Here, we have aimed at evaluating whether TSH has similar effects in vivo. For this purpose, we have evaluated the sequential profile of serum bone metabolism markers during acute stimulation with recombinant human TSH (rhTSH) in thyroidectomized women monitored for thyroid carcinoma.

MATERIALS AND METHODS

The study group included 66 thyroidectomized patients, of whom 38 were premenopausal and 28 postmenopausal, who underwent routine rhTSH-assisted whole body radioactive iodine scanning for differentiated thyroid carcinoma. The patients were sequentially evaluated for TSH, free triiodothyronine (FT3), free thyroxine (FT4), bone alkaline phosphatase (BALP), C-telopeptides of type-1 collagen (CrossLaps), and osteoprotegerin (OPG) levels during rhTSH stimulation. The samples were drawn just before and 2 and 7 days after the first administration of rhTSH. BMD was evaluated by ultrasonography at baseline. Seventy-one healthy women (41 premenopausal and 30 postmenopausal) acted as a control group.

RESULTS AND CONCLUSIONS

At study entry, all patients had subclinical thyrotoxicosis as effect of L-thyroxine (L-T4) treatment. The patients had higher serum CrossLaps and OPG levels and lower BMD than healthy subjects. Postmenopausal patients showed comparable serum FT4 and FT3 concentrations with those found in premenopausal patients. However, postmenopausal patients showed higher serum CrossLaps (p < 0.001), OPG (p = 0.03), and BALP (p < 0.001) levels and lower BMD (p < 0.001) than those measured in premenopausal patients. Two days after the first administration of rhTSH, all patients had serum TSH values >100 mUI/liter. At this time, serum CrossLaps levels decreased significantly (p < 0.001) and BALP values increased (p = 0.001) with respect to the baseline values in postmenopausal but not in premenopausal patients. rhTSH did not induce any significant change in serum OPG values either in premenopausal or in postmenopausal patients. One week after the first rhTSH administration, serum CrossLaps values decreased again to values comparable with those measured at baseline, whereas serum BALP values remained high. This study shows that subclinical thyrotoxicosis is accompanied by high bone turnover rate with an increase in serum OPG levels compared with euthyroid healthy subjects. Acute increase in serum TSH levels is accompanied by a reversible inhibition of bone resorption. This effect is characterized by a decrease in serum CrossLaps and an increase in BALP levels without any evident effect on OPG production. The activity of TSH occurs specifically in postmenopausal women in whom the negative effects of L-T4 suppressive therapy on bone mass and metabolism are more marked compared with premenopausal women.

High serum osteoprotegerin levels in patients with hyperthyroidism: effect of medical treatment

This study was aimed at evaluating serum osteoprotegerin (OPG) concentrations in a cohort of patients with hyperthyroidism before and after methimazole (MMI) treatment. One hundred fourteen hyperthyroid patients [93 with Graves disease (GD) and 21 with toxic nodular goitre (TNG)] and 68 matched for sex and age healthy subjects were evaluated for serum free-thyroxine (FT4), free-triiodiothyronine (FT3), thyrotropin (TSH), TSH receptor antibodies (TRAb), bone alkaline phosphatase (BALP), C-telopeptides of type-1 collagen (CrossLaps), OPG levels, and bone mineral density (BMD). In hyperthyroid patients, the biochemical evaluations were performed before and after 6 and 12 months of MMI treatment, whereas BMD was measured at baseline and after 12 months of treatment. Hyperthyroidism was more severe in GD than TNG patients. Serum OPG levels were found to be significantly higher in hyperthyroid patients than in the healthy subjects (4.3 pmol/l, range: 1.6-12.0, vs. 2.2 pmol/l, range: 1.4-6.0; P < 0.001), the values being higher in GD patients than TNG. A significant correlation between serum OPG levels and age was found in the healthy subjects (r: 0.48; P < 0.001) but not in hyperthyroid patients (r: -0.03; P = 0.8). In the healthy subjects, serum OPG levels were also positively correlated with both serum FT4 (r: 0.23; P = 0.03) and FT3 (r: 0.24; P = 0.04) levels. In hyperthyroid patients, however, serum OPG was still correlated with FT3 levels (r: 0.38; P < 0.001), whereas the correlation with serum FT4 was lost (r: 0.19; P = 0.06). In hyperthyroid patients, but not in the healthy subjects, serum OPG levels were correlated positively with CrossLaps (r: 0.20; P = 0.03) and negatively with BALP (r: -0.24; P = 0.01) and BMD (r: -0.33; P = 0.01). After 6 months of MMI treatment, serum OPG concentrations decreased significantly in TNG patients (from 3.5 pmol/l, range: 1.6-8.0, to 2.3 pmol/l, range: 1.0-4.3; P < 0.001), whereas a not significant change in OPG levels occurred in GD patients (from 4.8 pmol/l, range: 1.8-12.0, to 4.2 pmol/l, range: 1.0-14.0; P = 0.7). At Month 12 of treatment, serum OPG concentrations were significantly lower than those measured at baseline in both TNG (2.5 pmol/l, range: 1.0-3.1, vs. 3.5 pmol/l, range: 1.6-8.0; P < 0.001) and GD (2.1 pmol/l, range: 1.0-8.6, vs. 4.8 pmol/l, range: 1.8-12.0; P < 0.001). At this time, no significant differences in serum OPG, CrossLaps, and BALP values were found between patients and control subjects. At the end of follow-up, BMD was higher than those measured at baseline but still significantly lower than those measured in the control subjects. This study shows that hyperthyroid patients have serum OPG concentrations significantly higher in comparison with euthyroid subjects, in relation to thyroid hormone excess and high bone turnover. Medical treatment of hyperthyroidism normalizes serum OPG levels in temporal relationship with the normalization of bone metabolism markers, even in presence of persistent abnormal bone structure as determined by ultrasonography.

Serum Osteocalcin Levels in Hyperthyroidism before and after Antithyroid Therapy

Hyperthyroidism is characterized by accelerated bone turnover, caused from direct stimulation of bone cells by increased thyroid hormones. In this study, we aimed to investigate serum osteocalcin levels as a bone formation marker, before antithyroid (propylthiouracil) therapy at hyperthyroid stage and after antithyroid therapy at euthyroid stage of the patients. Twenty four hyperthyroid patients (18 females, 6 males) and 20 (13 females, 7 males) healthy controls were included into this study. Blood and urine samples were taken before medical treatment at hyperthyroid state, and after the antithyroid therapy until the patients reached the euthyroid state. Serum alkaline phosphatase, osteocalcin, calcium, phosphorus, Free T3, Free T4, TSH and urine calcium/creatinine levels were assessed. We found a significant decrease in serum osteocalcin (p=0.006), urinary calcium/creatinine (p=0.004), and serum phosphorus (p=0.038) levels in euthyroid state in comparison to hyperthyroid state. The increases in serum bone formation marker osteocalcin and bone resorption marker urinary calcium/creatinine levels in hyperthyroid state compared to euthyroid state in our study confirmed that hyperthyroid patients have high bone turnover. We conclude that, hyperthyroid patients has high bone turnover of formation and resorption even after attainment of euthyroidism. Osteocalcin and urine calcium/creatinine are sensitive markers in documenting bone remodeling during treatment of hyperthyroidism.