Carboxy-terminal propeptide of type 1 procollagen (P1CP) and carboxy-terminal telopeptide of type 1 collagen (1CTP) as sensitive markers of bone metabolism in thyroid disease

Diagnosis and therapeutic approach to bone health in patients with hypopituitarism

The results of many studies in recent years indicate a significant impact of pituitary function on bone health. The proper function of the pituitary gland has a significant impact on the growth of the skeleton and the appearance of sexual dimorphism. It is also responsible for achieving peak bone mass, which protects against the development of osteoporosis and fractures later in life. It is also liable for the proper remodeling of the skeleton, which is a physiological mechanism managing the proper mechanical resistance of bones and the possibility of its regeneration after injuries. Pituitary diseases causing hypofunction and deficiency of tropic hormones, and thus deficiency of key hormones of effector organs, have a negative impact on the skeleton, resulting in reduced bone mass and susceptibility to pathological fractures. The early appearance of pituitary dysfunction, i.e. in the pre-pubertal period, is responsible for failure to achieve peak bone mass, and thus the risk of developing osteoporosis in later years. This argues for the need for a thorough assessment of patients with hypopituitarism, not only in terms of metabolic disorders, but also in terms of bone disorders. Early and properly performed treatment may prevent patients from developing the bone complications that are so common in this pathology. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary disease.

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.

Vitamin E management of oxidative damage-linked dysfunctions of hyperthyroid tissues

INTRODUCTION

Thyroid hormones affect growth, development, and metabolism of vertebrates, and are considered the major regulators of their homeostasis. On the other hand, elevated circulating levels of thyroid hormones are associated with modifications in the whole organism (weight loss and increased metabolism and temperature) and in several body regions. Indeed, tachycardia, atrial arrhythmias, heart failure, muscle weakness and wasting, bone mass loss, and hepatobiliary complications are commonly found in hyperthyroid animals and humans.

RESULTS

Most thyroid hormone actions result from influences on transcription of T3-responsive genes, which are mediated through nuclear receptors. However, there is significant evidence that tissue oxidative stress underlies some dysfunctions produced by hyperthyroidism.

DISCUSSION

During the last decades, increasing interest has been turned to the use of antioxidants as therapeutic agents in various diseases and pathophysiological disorders believed to be mediated by oxidative stress. In particular, because elevated circulating levels of thyroid hormones are associated with tissue oxidative injury, more attention has been paid to explore the application of antioxidants as therapeutic agents in thyroid related disorders.

CONCLUSIONS

At present, vitamin E is among the most commonly consumed dietary supplements due to the belief that it, as an antioxidant, may attenuate morbidity and mortality. This is due to the results of numerous scientific studies, which demonstrate that vitamin E has a primary function to destroy peroxyl radicals, thus protecting polyunsaturated fatty acids biological membranes from oxidative damage. However, results are also available indicating that protective vitamin E effects against oxidative damage can be obtained even through different mechanisms.

Influence of brain injury on early posttraumatic bone metabolism

BACKGROUND

Various clinical studies and observations demonstrate enhanced osteogenesis in patients sustaining traumatic brain injury. It is presumed that the induction of this process starts early after trauma. The purpose of our study was to investigate humoral markers of bone metabolism during the early posttraumatic period, with special regard to traumatic brain injury.

METHODS

Serum concentrations of biochemical markers of bone metabolism (calcium, inorganic phosphorus, carboxyl-terminal propeptide of type 1 procollagen, pyridinoline cross-linked telopeptide domain of type 1 collagen, Ostase, osteocalcin, intact parathyroid hormone, and calcitonin) were measured in three different groups of 80 patients during the first posttraumatic week. Patients were categorized into three groups: group I, fractures only; group II, isolated traumatic brain injury; and group III, traumatic brain injury in combination with fractures.

RESULTS

Osteocalcin levels were significantly lower in the presence of traumatic brain injury (p < .05). Elevated pyridinoline cross-linked telopeptide domain of type 1 collagen levels expressed enhanced bone resorption in all groups, but levels were significantly higher in the absence of traumatic brain injury (p < .05). Intact parathyroid hormone levels were significantly higher on days 0 and 1 in the combined presence of traumatic brain injury plus fractures.

CONCLUSION

These results demonstrate an imbalance of bone formation and resorption parameters in patients with traumatic brain injury during the early posttraumatic period, suggesting a central regulation in bone formation. The lower levels of osteocalcin detected in this study may play an important role in patients with brain injury and the later development of posttraumatic heterotopic ossification.

Longitudinal changes of bone density and bone resorption in hyperthyroid girls during treatment

Low bone mineral density (BMD) and increased bone turnover are common features of untreated hyperthyroidism in adult patients. The effect of treatment on BMD is still controversial. BMD and bone metabolism in hyperthyroid children have not been thoroughly investigated. In the present study, we measured spinal and whole body BMD by dual-energy X-ray absorptiometry in a group of 13 girls (aged 5.0-14.9 years) at diagnosis of hyperthyroidism. The bone resorption rate was assessed by urine measurement of N-terminal telopeptide of type I collagen (NTX). Hyperthyroid patients have been studied longitudinally during treatment. BMD values and NTX urine concentrations have been also determined in 155 healthy Caucasian girls (aged 2.4-24.2 years). Spinal and whole body bone density measurements were significantly lower compared with healthy controls in untreated hyperthyroid girls, after correction for differences in age and anthropometric measurements (p </= 0.033). Bone density measurements obtained after 12 and 24 months of treatment were no longer different from those of healthy girls. NTX urine levels at diagnosis of thyrotoxicosis were significantly higher than those found in healthy controls (p < 0.0001); 6 months after treatment, the urine levels did not show significant differences, and they remained stable after 12 and 24 months of therapy. Inverse correlations at diagnosis were found between serum-free thyroxine (FT4) serum levels and spinal (r = -0.42) and whole body bone density (r = -0.41); FT4 and free triiodothyronine serum levels directly correlated with the NTX concentration (r = 0. 77, and r = 0.71, respectively). In conclusion, the results of the present study demonstrate that low bone density values and high bone resorption rates are found in hyperthyroid children and adolescents at diagnosis of the disease. Our data also demonstrate that antithyroid treatment is able to reduce dramatically the bone resorption and to increase significantly both spinal and total body BMD, granting physiologic conditions for the achievement of the best obtainable peak bone mass.