New insights into vitamin D regulation: is there a role for alkaline phosphatase?

PURPOSE

The diagnosis of vitamin D deficiency is based on the determination of total plasma 25-hydroxyvitamin D (25-OHD) concentrations, but the regulation of vitamin D 25-hydroxylation is not a major consideration and very little information is available on this activity. To check what factors could interfere with the activity of vitamin D-25-hydroxylase and thus alter the 25-OHD concentrations, we looked for potential correlations between 25-OHD and results of liver function tests in healthy adults.

METHODS

This single-centre study was retrospective and consisted of evaluating the correlations between 25-OHD and the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and bone alkaline phosphatase (BALP) in 349 healthy subjects aged from 18 to 65 years. In particular, in Group 1 (n = 119), we looked for correlations between 25OHD and all liver function tests and in Group 2 (n = 230) the correlation between 25OHD and BALP.

RESULTS

In Group 1, we found no correlation between 25OHD and AST (r =  - 0.03; p = 0.8), ALT (r =  - 0.02; p = 0.91), GGT (r =  - 0.08; p = 0.68), direct bilirubin (r =  - 0.02; p = 0.89), indirect bilirubin (r =  - 0.24; p = 0.21), and total bilirubin (r =  - 0.24; p = 0.21) but one between 25OHD and ALP (r =  - 0.2; p = 0.007); in Group 2, we found a significant negative correlation between 25-OHD and BALP (r =  - 0.2; p = 0.0008).

CONCLUSIONS

The correlations that we found suggest that ALP and BALP might be involved in the regulation of vitamin D-25-hydroxylase activity, but further studies are mandatory to confirm our assumptions.

Endocrine rhythms and sport: it is time to take time into account

BACKGROUND

Studies of time-related biological phenomena have contributed to establishing a new scientific discipline, the chronobiology, which considers biological phenomena in relation to time. Sports activity profoundly affects the temporal organization of the organism and endocrine rhythms play a key role in the chronoorganization of individuals and are particularly important for correct physical activity. Correctly reading rhythmic hormonal variations of the human organism opens new horizons to sports medicine.

OBJECTIVE

This review is aimed at clarifying the relationship between endocrine rhythms and sports activities on the basis of the latest data in the literature.

METHOD

Data acquisition was obtained from three databases (PubMed, Scopus and SPORTDiscus), paying particular attention to reviews, meta-analysis, original and observational studies on this issue.

RESULTS

After the description of the general characteristics and parameters of biological rhythms, the main endocrine rhythms will be described, highlighting in particular the interrelationships with sports activity and focusing on the factors which can affect negatively their characteristics and consequently the psychophysical performances of the athletes.

CONCLUSION

Knowledge of this issue may allow establishing the best form of competitive or amateur activity, through the collaboration of an informed athlete and a sports physician attentive to biological rhythms. By taking into account that alteration of physiological rhythmic temporal organization can favour the onset of important diseases, including cancer, this will lead to the expected performances without impairing the correct chronoorganization of the athlete.

TSH oscillations in young patients with type 1 diabetes may be due to glycemic variability

PURPOSE

A relationship between thyroid dysfunction and diabetes mellitus has been described by several authors but the role of glycemic variability is still unclear. We planned the present study to evaluate the influence of glycemic variability on thyroid hormones and TSH concentrations in patients with type 1 diabetes mellitus (T1DM).

METHODS

Seventy-seven young patients with T1DM were enrolled and evaluated for basal glucose concentrations, HbA1c, thyroid hormones and TSH concentrations. Glucose variability was investigated by considering the standard deviation of blood glucose readings and by calculating the mean amplitude of glycemic excursions and continuous overlapping net glycemic action (CONGA). The low (LBGI) and high (HBGI) blood glucose indices were also calculated. The correlations between TSH, thyroid hormones, glycemia and HbA1c were studied in patients and in controls, whereas those between TSH, thyroid hormones and indices of glucose variability only in patients.

RESULTS

No correlations were observed in T1DM patients between free thyroid hormones and glycemic values, HbA1c and indices of glucose variability, while an inverse correlation was observed between TSH levels and glycemic values (r = -0.27; p = 0.01), CONGA index (r = -0.35; p = 0.001) and HBGI (r = -0.28; p = 0.01) but not with HbA1c (r = -0.1; p = 0.47).

CONCLUSIONS

Our results suggest a direct action of glycemic excursions on TSH secretion, regardless of variations of thyroid hormone concentrations. Thus, the evaluation of thyroid function through the assay of TSH concentrations in these patients should be made, if possible, by multiple samples on patients in euglycemic state to avoid underestimation or overestimation of thyroid dysfunction due to a wrong diagnosis of euthyroidism or dysthyroidism with consequent inappropriate choice of therapeutic options.

Prospective investigation of pituitary functions in patients with acute infectious meningitis: is acute meningitis induced pituitary dysfunction associated with autoimmunity?

Previous case reports and retrospective studies suggest that pituitary dysfunction may occur after acute bacterial or viral meningitis. In this prospective study we assessed the pituitary functions, lipid profile and anthropometric measures in adults with acute bacterial or viral meningitis. Moreover, in order to investigate whether autoimmune mechanisms could play a role in the pathogenesis of acute meningitis-induced hypopituitarism we also investigated the anti-pituitary antibodies (APA) and anti-hypothalamus antibodies (AHA) prospectively. Sixteen patients (10 males, 6 females; mean ± SD age 40.9 ± 15.9) with acute infectious meningitis were included and the patients were evaluated in the acute phase, and at 6 and 12 months after the acute meningitis. In the acute phase 18.7% of the patients had GH deficiency, 12.5% had ACTH and FSH/LH deficiencies. At 12 months after acute meningitis 6 of 14 patients (42.8%) had GH deficiency, 1 of 14 patients (7.1%) had ACTH and FSH/LH deficiencies. Two of 14 patients (14.3%) had combined hormone deficiencies and four patients (28.6%) had isolated hormone deficiencies at 12 months. Four of 9 (44.4%) hormone deficiencies at 6 months were recovered at 12 months, and 3 of 8 (37.5%) hormone deficiencies at 12 months were new-onset hormone deficiencies. At 12 months there were significant negative correlations between IGF-I level vs. LDL-C, and IGF-I level vs. total cholesterol. The frequency of AHA and APA positivity was substantially high, ranging from 35 to 50% of the patients throughout the 12 months period. However there were no significant correlations between AHA or APA positivity and hypopituitarism. The risk of hypopituitarism, GH deficiency in particular, is substantially high in the acute phase, after 6 and 12 months of the acute infectious meningitis. Moreover we found that 6th month after meningitis is too early to make a decision for pituitary dysfunction and these patients should be screened for at least 12 months. In addition, the occurrence of AHA and APA positivity due to acute infectious meningitis was demonstrated for the first time. Further longer-term prospective investigations need to be carried out on a larger cohort of patients to understand the role of autoimmunity in the pathogenesis of late hypopituitarism after acute infectious meningitis.

Remission of subclinical adrenocortical failure in subjects with adrenal autoantibodies

Idiopathic Addison's disease is a chronic organ-specific autoimmune disorder with a long subclinical period characterized only by the presence of adrenal autoantibodies (AA) with or without adrenal function failure. The aim of this longitudinal study was to evaluate the behavior of AA using, an indirect fluorescence method, and adrenal function in 20 AA-positive and 50 AA-negative patients screened by an investigation of a large population of organ-specific autoimmune disease patients without clinical Addison's disease. As controls, 100 normal age-matched subjects were tested only once. In the 20 AA-positive and 50 negative patients, AA and adrenal functional tests were evaluated every 4 months for 5 yr. The AA-positive patients were grouped into 5 adrenal functional stages, specifically: stage 0, normal adrenal function; stage 1, high PRA and low (or normal) aldosterone levels alone; stage 2, along with impaired cortisol response to ACTH, stage 3, along with increased ACTH levels; and stage 4, clinically overt Addison's disease. On the basis of the behavior of AA, the 20 positive patients were grouped as follows: group A, 11 patients with AA titer of 1:8 or higher at the first observation and persistently AA positive in subsequent observations, with titers ranging from 1:8 to 1:64; group B, 6 patients with initial AA titers of 1:8 or lower and AA disappearance in subsequent observations; and group C, 3 patients with AA titer of 1:32 or higher, undergoing corticosteroid therapy after the start of the study and showing AA disappearance in subsequent observations. With respect to adrenal function in group A, 2 patients initially in stage 1 and 1 patient initially in stage 2 did not progress to the upper stages, whereas 5 patients initially in stage 0 and 3 initially in stage 1 progressed subsequently to the upper stages, in 2 cases reaching overt clinical Addison's disease (stage 4). On the other hand, all of the patients of group B showed both a spontaneous disappearance of AA and recovery of adrenal function during the study span. Also, the 3 patients of group C showed disappearance of AA after corticosteroid therapy with recovery of adrenal function. None of the 50 patients who were initially AA negative became AA positive subsequently or showed impairment of adrenal function. We reached the following conclusions. 1) AA, even if present initially in some subjects without clinical Addison's disease, can subsequently disappear. 2) Restoration of adrenal function after disappearance of AA indicates that a spontaneous remission of subclinical adrenocortical failure can occur.(ABSTRACT TRUNCATED AT 400 WORDS)