Cortisol and Phosphate Homeostasis: Cushing's Syndrome Is Associated With Reversible Hypophosphatemia

OBJECTIVES

The influence of hypercortisolism on phosphate homeostasis is relatively unknown. A few previous studies have reported on patients with Cushing's syndrome (CS) with hypophosphatemia in whom serum phosphate normalized after initiation of treatment for CS. We aimed to investigate the prevalence of hypophosphatemia in CS, the association between the degree of hypercortisolism and serum phosphate and the change in serum phosphate after remission of CS. We compared the prevalence of hypophosphatemia in CS with the prevalence in the population-based Rotterdam Study (RS).

METHODS

Patients diagnosed with CS and treated at the Department of Endocrinology of Erasmus MC in the period of 2002-2020 were included and data was collected on age at diagnosis, sex, serum phosphate, calcium and potassium levels, kidney function and BMI. Using multivariate linear regression, we analyzed the association between 24h urinary free cortisol excretion (UFC) and serum phosphate. Changes in serum phosphate and covariates were tested with a repeated measurement ANOVA, using mean levels of laboratory values for the periods before remission, and 0-14 days and 15-180 days after remission.

RESULTS

Hypophosphatemia before treatment was present in 16% of the 99 CS patients with data on serum phosphate, 24h UFC and covariates. In comparison, the prevalence of hypophosphatemia in RS was 2.0-4.2%. Linear regression showed a negative association between the level of UFC and serum phosphate at diagnosis, which remained significant after adjusting for covariates [β -0.002 (95%CI -0.004; -0.0004), p=0.021]. A subset of 24 patients had additional phosphate measurements at 0-14 days and 15-180 days after remission. In this subgroup, serum phosphate significantly increased from 1.03 ± 0.17 mmol/L prior to remission to 1.22 ± 0.25 mmol/L 15-180 days after remission (p = 0.008). BMI decreased after remission [-1.1 kg/m², (95%CI -2.09 to -0.07), p=0.037]. Other covariates did not show an equivalent change over time.

CONCLUSION

In this retrospective study, we found that 16% of patients with CS had hypophosphatemia. Moreover, serum phosphate was related to the level of cortisoluria and increased after remission of CS. Potential underlying mechanisms related to urinary phosphate excretion and possibly involving FGF23, BMI and parathyroid hormone levels should be further explored.

SUGAR-DIP trial: oral medication strategy versus insulin for diabetes in pregnancy, study protocol for a multicentre, open-label, non-inferiority, randomised controlled trial

INTRODUCTION

In women with gestational diabetes mellitus (GDM) requiring pharmacotherapy, insulin was the established first-line treatment. More recently, oral glucose lowering drugs (OGLDs) have gained popularity as a patient-friendly, less expensive and safe alternative. Monotherapy with metformin or glibenclamide (glyburide) is incorporated in several international guidelines. In women who do not reach sufficient glucose control with OGLD monotherapy, usually insulin is added, either with or without continuation of OGLDs. No reliable data from clinical trials, however, are available on the effectiveness of a treatment strategy using all three agents, metformin, glibenclamide and insulin, in a stepwise approach, compared with insulin-only therapy for improving pregnancy outcomes. In this trial, we aim to assess the clinical effectiveness, cost-effectiveness and patient experience of a stepwise combined OGLD treatment protocol, compared with conventional insulin-based therapy for GDM.

METHODS

The SUGAR-DIP trial is an open-label, multicentre randomised controlled non-inferiority trial. Participants are women with GDM who do not reach target glycaemic control with modification of diet, between 16 and 34 weeks of gestation. Participants will be randomised to either treatment with OGLDs, starting with metformin and supplemented as needed with glibenclamide, or randomised to treatment with insulin. In women who do not reach target glycaemic control with combined metformin and glibenclamide, glibenclamide will be substituted with insulin, while continuing metformin. The primary outcome will be the incidence of large-for-gestational-age infants (birth weight >90th percentile). Secondary outcome measures are maternal diabetes-related endpoints, obstetric complications, neonatal complications and cost-effectiveness analysis. Outcomes will be analysed according to the intention-to-treat principle.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of the Utrecht University Medical Centre. Approval by the boards of management for all participating hospitals will be obtained. Trial results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NTR6134; Pre-results.

IGFBP-2 and aging: a 20-year longitudinal study on IGFBP-2, IGF-I, BMI, insulin sensitivity and mortality in an aging population

Objective Insulin-like growth factor-binding protein-2 (IGFBP-2) concentrations are low in subjects with metabolic syndrome and type 2 diabetes. Intriguingly, recent studies have demonstrated an association between high IGFBP-2 concentrations and increased mortality not only in populations with certain types of cancer, but also in relatively healthy populations. We evaluated the role of IGFBP-2 in relation to BMI and mortality. Design and Participants BMI, insulin sensitivity, insulin-like growth factor 1 (IGF-I) and IGFBP-2 were assessed repeatedly in 539 participants of the Baltimore Longitudinal Study of Aging around the ages of 55, 65 and 75 years. Results IGFBP-2 concentrations positively correlated with insulin sensitivity and inversely with BMI, both at baseline and follow-up. Independent of IGF-I, sex, BMI and insulin sensitivity, circulating IGFBP-2 levels positively correlated with age (P < 0.001). Changes over time in BMI were associated with an inverse correlation in IGFBP-2 concentrations. Furthermore, we found indications of a relationship between low baseline IGFBP-2 levels and mortality. Remarkably, after adjustment for insulin sensitivity, the opposite association was found, as a unit increase of log(IGFBP2) was associated with an increase in the log hazard by 1.43 (95% CI: 0.3-2.6). This accounted for both baseline (P = 0.02) as well as serial (P < 0.001) measurements of IGFBP2. Finally, in this longitudinal study, we found that IGF-I concentrations increased with age (0.82 ± 0.2 (µg/L)/year, P < 0.001). Conclusion This is the first study investigating the relationship between IGFBP-2 levels and age in a longitudinal setting. Serum IGFBP-2 levels increase with age after the age of 50 years and evolve in parallel with insulin sensitivity. IGFBP-2 may therefore be a potential marker for insulin sensitivity. We further show that IGFBP-2 levels can predict mortality in this aging population. However, its predictive value for mortality can only be interpreted in relation to insulin sensitivity. After adjustment for insulin sensitivity, high IGFBP-2 levels are predictive of increased mortality.

The physiology of endocrine systems with ageing

During ageing, the secretory patterns of the hormones produced by the hypothalamic-pituitary axis change, as does the sensitivity of the axis to negative feedback by end hormones. Additionally, glucose homoeostasis tends towards disequilibrium with increasing age. Along with these endocrine alterations, a loss of bone and muscle mass and strength occurs, coupled with an increase in fat mass. In addition, ageing-induced effects are difficult to disentangle from the influence of other factors that are common in older people, such as chronic diseases, inflammation, and low nutritional status, all of which can also affect endocrine systems. Traditionally, the decrease in hormone activity during the ageing process has been considered to be detrimental because of the related decline in bodily functions. The concept of hormone replacement therapy was suggested as a therapeutic intervention to stop or reverse this decline. However, clearly some of these changes are a beneficial adaptation to ageing, whereas hormonal intervention often causes important adverse effects. In this paper, we discuss the effects of age on the different hypothalamic-pituitary-hormonal organ axes, as well as age-related changes in calcium and bone metabolism and glucose homoeostasis.

Selenium Status Is Positively Associated with Bone Mineral Density in Healthy Aging European Men

Objective

It is still a matter of debate if subtle changes in selenium (Se) status affect thyroid function tests (TFTs) and bone mineral density (BMD). This is particularly relevant for the elderly, whose nutritional status is more vulnerable.

Design and Methods

We investigated Se status in a cohort of 387 healthy elderly men (median age 77 yrs; inter quartile range 75–80 yrs) in relation to TFTs and BMD. Se status was determined by measuring both plasma selenoprotein P (SePP) and Se.

Results

The overall Se status in our population was low normal with only 0.5% (2/387) of subjects meeting the criteria for Se deficiency. SePP and Se levels were not associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroxine (T4), triiodothyronine (T3) or reverse triiodothyronine (rT3) levels. The T3/T4 and T3/rT3 ratios, reflecting peripheral metabolism of thyroid hormone, were not associated with Se status either. SePP and Se were positively associated with total BMD and femoral trochanter BMD. Se, but not SePP, was positively associated with femoral neck and ward's BMD. Multivariate linear analyses showed that these associations remain statistically significant in a model including TSH, FT4, body mass index, physical performance score, age, smoking, diabetes mellitus and number of medication use.

Conclusion

Our study demonstrates that Se status, within the normal European marginally supplied range, is positively associated with BMD in healthy aging men, independent of thyroid function. Thyroid function tests appear unaffected by Se status in this population.

High IGFBP2 levels are not only associated with a better metabolic risk profile but also with increased mortality in elderly men

OBJECTIVE

Serum IGF-binding protein 2 (IGFBP2) concentrations are reduced in obese humans and increase after a prolonged period of fasting. We investigated the association between IGFBP2 levels and mortality together with other factors that are related to IGFBP2, including the metabolic syndrome and physical function.

DESIGN

A prospective observational study at a clinical research center of 403 independently living elderly men (aged 73-94 years).

METHODS

Mortality was registered during 8.6 years of follow-up. Physical performance score (PPS), grip strength (GS), and bone mineral density (BMD) were measured. The measurements taken a baseline were: IGF1; IGFBP1, -2, and -3; IGF1 bioactivity; triiodothyronine (T(3)); and reverse T(3). Further, BMI, insulin sensitivity, cholesterol, inflammatory markers, and albumin levels were also measured.

RESULTS

During the follow-up, 180 men died. Higher PPS, GS, and BMD were independently related to a reduced mortality (hazard ratio (HR)=0.87/point, 95% confidence interval (95% CI)=0.82-0.91, P<0.001; HR=0.96/kp, 95% CI 0.94-0.98, P<0.001; and HR=0.21/(g/cm(2)), 95% CI 0.07-0.61, P<0.01). Higher serum IGFBP2 levels were strongly related to mortality (HR=2.26/(mg/l), 95% CI 1.57-3.27, P<0.001). This was independent of comorbidity, physical function, IGF1 bioactivity, and other somatotropic parameters, including BMI and the metabolic syndrome. In addition, IGFBP2 levels were higher in subjects with nonthyroidal illness, and higher IGFBP2 levels were significantly associated with lower albumin concentrations.

CONCLUSION

Despite the strong relationship between high IGFBP2 and low physical function, both were strongly and independently related to increased 8-year mortality in elderly men. IGFBP2 may be a useful biomarker integrating the nutritional status, as well as the biological effects of GH, IGF1, and insulin.

Sex hormones and cognitive decline in elderly men

Decline of cognitive function with age may be due, in part, to hormonal changes and it has been hypothesized that higher levels of endogenous sex hormones preserve brain function. The aim of this prospective cohort study was to determine the relative contribution of endogenous sex hormones to cognitive decline in a population-based sample of 242 elderly men aged 73-91 at baseline. Endogenous sex hormone levels were measured at baseline and participants underwent a cognitive assessment at baseline and at follow-up after 4 years. Higher estradiol (total and bioavailable) and estrone levels were associated with an increased risk of cognitive decline in elderly men independent of age, cardiovascular risk factors, atherosclerosis, and APOE genotype. These findings do not support the hypotheses that higher levels of endogenous sex hormones preserve brain function.

The Asp727Glu polymorphism in the TSH receptor is associated with insulin resistance in healthy elderly men

BACKGROUND

Variations in thyroid function within the normal range are associated with differences in metabolism and body composition. For instance, TSH is positively associated with body mass index (BMI). This could be due to alterations in thyroid hormone activity, or to direct effects of TSH, as the TSH receptor (TSHR) is also expressed in adipose tissue. The TSHR-Asp727Glu polymorphism is associated with lower serum TSH levels in vivo. In this study, we analysed whether serum thyroid parameters and the TSHR-Asp727Glu polymorphism were associated with glucose metabolism and insulin resistance. In addition, we analysed the Thr92Ala polymorphism in the type 2 deiodinase (D2), which was recently associated with insulin resistance.

METHODS

Genotypes were determined in a population of 349 elderly men (age 77.7 +/- 3.5 years), for whom serum thyroid parameters and data on insulin resistance, such as fasting blood glucose, serum insulin and homeostasis model assessment (HOMA) values, were available.

RESULTS

In nondiabetic, euthyroid subjects, TSH was positively associated with leptin levels, whereas FT4 and rT3 were significantly negatively correlated with insulin and HOMA. Carriers of the TSHR-Glu727 allele had a significantly higher glucose (P = 0.01), insulin (P = 0.001), glycated haemoglobin (HbA1c) (P = 0.002), HOMA (P = 0.001) and leptin (P = 0.008). The D2-Ala(92) allele showed a trend towards higher levels of insulin (P = 0.07) and a higher HOMA (P = 0.09).

CONCLUSION

In this population of nondiabetic elderly men, serum thyroid parameters and the TSHR-Asp727Glu polymorphism were associated with relative insulin resistance. Our study suggests that genetic variation in TSHR plays a role in insulin resistance and thereby influences glucose metabolism.

Lack of Association of the 11beta-hydroxysteroid dehydrogenase type 1 gene 83,557insA and hexose-6-phosphate dehydrogenase gene R453Q polymorphisms with body composition, adrenal androgen production, blood pressure, glucose metabolism, and dementia

CONTEXT

Recently, it was proposed that a combination of the 83,557insA polymorphism in the 11beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) gene and the R453Q polymorphism in the hexose-6-phosphate dehydrogenase (H6PD) gene interacts to cause cortisone reductase deficiency (CRD) when at least three alleles are affected.

OBJECTIVE

The aim was to study the separate and combined effects of these polymorphisms on body composition, adrenal androgen production, blood pressure, glucose metabolism, and the incidence of dementia in the healthy elderly population.

DESIGN/SETTING/PARTICIPANTS

The Rotterdam study (n = 6105) and the Frail Old Men study (n = 347) are population-based cohort studies in the elderly.

MAIN OUTCOME MEASURES

Genotype distributions and influences of (combined) genotypes on body mass index, adrenal androgen production, waist to hip ratio, systolic and diastolic blood pressure, fasting glucose levels, glucose tolerance test, and incidence of dementia were measured.

RESULTS

No influence of the HSD11B1 83,557insA (allele frequencies 22.0 and 21.5%) and H6PD R453Q (allele frequencies 22.9 and 20.2%) variants was found for the different outcome measures that were investigated, either separately or when at least three alleles were affected.

CONCLUSIONS

Two population-based studies among Caucasian elderly showed no evidence for (combined) effects of two polymorphisms in the HSD11B1 and H6PD genes on body composition, adrenal androgen production, blood pressure, glucose metabolism, and incidence of dementia. Moreover, the high frequencies observed for these two polymorphisms do not correspond to the low incidence of CRD observed in the general population. Altogether, it is unlikely that these polymorphisms cause CRD.

Effects of dehydroepiandrosterone and atamestane supplementation on frailty in elderly men

BACKGROUND

It has been suggested that the age-related decline of androgens in men plays a distinct role in the development of several aspects of frailty. Therefore, hormone replacement might improve the course of frailty by increasing lean body mass and muscle strength, decreasing fat mass, and improving the subjective quality of life.

OBJECTIVE

The objective of the study was to assess whether hormone replacement with dehydroepiandrosterone (DHEA) and/or atamestane might improve the course of frailty.

DESIGN

This was a double-blind, randomized, controlled trial.

SETTING

The study was conducted in the general community.

PARTICIPANTS

Participants included 100 nonhospitalized, nondiseased, independently living men, aged 70 yr and over with low scores on strength tests. Seventeen participants did not complete the trial.

INTERVENTION

Subjects were randomly assigned to one of four intervention arms: atamestane (100 mg/d) and placebo, DHEA (50 mg/d) and placebo, a combination of atamestane (100 mg/d) and DHEA (50 mg/d), or two placebo tablets for 36 wk.

MAIN OUTCOME MEASURES

Physical frailty was measured by means of a specific test battery, including isometric grip strength, leg extensor power, and physical performance.

RESULTS

The randomization was successful, and 83 (83%) men completed the intervention. There were no differences between the treatment arms and placebo group in any of the outcome measurements after intervention.

CONCLUSIONS

The results of this double-blind, randomized trial do not support the hypothesis that hormone replacement with DHEA and/or atamestane might improve the course of frailty.

Prediction of mortality risk in the elderly

PURPOSE

Ways to predict the risk of cardiovascular (CV) events or all-cause mortality have largely been derived from populations in which old and very old subjects were underrepresented. We set out to estimate the incremental prognostic utility of inflammation and atherosclerosis markers in the prediction of all-cause and CV mortality in elderly men.

METHODS

In a prospective population-based cohort study, conventional CV risk factors were documented in 403 independently living elderly men. C-reactive protein (CRP) and interleukin (IL)-6 levels were measured. Carotid plaques were assessed by ultrasound. Analyses were performed with proportional hazards analyses, and bootstrapping was used for internal validation. Main outcome was CV and all-cause mortality occurring during 4 years of follow-up.

RESULTS

Increasing tertiles of CRP, IL-6, and number of plaques were independently associated with all-cause and CV mortality. With information on age, carotid plaques, IL-6, and CRP yielded good discriminatory power for all-cause and CV mortality: area under the receiver operating characteristic curve (95% confidence interval), 0.76 (0.70-0.82) and 0.74 (0.68-0.80), respectively. Combined use of only IL-6 and plaque burden allowed identification of subjects with low and high mortality risk. The Framingham PROCAM and a Dutch Risk Function poorly predicted mortality risk, similar or worse than a model using age alone.

CONCLUSION

In the old and very old, IL-6 and number of carotid plaques are powerful predictors of mortality risk in the years to come. Conventional risk scores seem to perform unsatisfactorily.

Thyroid hormone concentrations, disease, physical function, and mortality in elderly men

CONTEXT

Physiological changes in thyroid hormone concentrations might be related to changes in the overall physical function in the elderly.

OBJECTIVE

We determined to what extent thyroid hormone concentrations are related to physical function and mortality in elderly men.

DESIGN

A longitudinal population study (the Zoetermeer study) was conducted. Mortality was registered in the subsequent 4 yr.

PARTICIPANTS

Four hundred three independently and ambulatory living men (aged 73-94 yr) participated.

MAIN OUTCOME MEASURES

The study examined the association between serum thyroid hormones and parameters of physical function as well as the association with mortality.

METHODS

TSH, free T4 (FT4) total T4, T3, rT3, and T4-binding globulin were measured. Physical function was estimated by the number of problems in activities of daily living, a measure of physical performance score (PPS), leg extensor strength and grip strength, bone density, and body composition.

RESULTS

Serum rT3 increased significantly with age and the presence of disease. Sixty-three men met the biochemical criteria for the low T3 syndrome (decreased serum T3 and increased serum rT3). This was associated with a lower PPS, independent of disease. Furthermore, higher serum FT4 (within the normal range of healthy adults) and rT3 (above the normal range of healthy adults) were related with a lower grip strength and PPS, independent of age and disease. Isolated low T3 was associated with a better PPS and a higher lean body mass. Low FT4 was related to a decreased risk of 4-yr mortality.

CONCLUSIONS

In a population of independently living elderly men, higher FT4 and rT3 concentrations are associated with a lower physical function. High serum rT3 may result from a decreased peripheral metabolism of thyroid hormones due to the aging process itself and/or disease and may reflect a catabolic state. Low serum FT4 is associated with a better 4-yr survival; this may reflect an adaptive mechanism to prevent excessive catabolism.

A common polymorphism in the CYP3A7 gene is associated with a nearly 50% reduction in serum dehydroepiandrosterone sulfate levels

CONTEXT

CYP3A7, expressed in the human fetal liver and normally silenced after birth, plays a major role in the 16alpha-hydroxylation of dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), and estrone. Due to a replacement of part of the CYP3A7 promoter with a sequence identical with the same region in the CYP3A4 promoter (referred to as CYP3A7*1C), some individuals still express a variant of the CYP3A7 gene later in life.

OBJECTIVE

The objective of this study was to examine the effect of the CYP3A7*1C polymorphism on serum steroid hormone levels.

DESIGN, SETTING, PARTICIPANTS

Two population-based cohort studies were performed. Study group 1 consisted of 208 subjects randomly selected from the Rotterdam Study, and study group 2 consisted of 345 elderly independently living men.

MAIN OUTCOME MEASURES

Serum DHEA(S), androstenedione, estradiol, estrone, and testosterone levels were the main outcome measures.

RESULTS

In study groups 1 and 2, heterozygous CYP3A7*1C carriers had almost 50% lower DHEAS levels compared with homozygous carriers of the reference allele [study group 1, 1.74 +/- 0.25 vs. 3.33 +/- 0.15 micromol/liter (P = 0.02); study group 2, 2.09 +/- 0.08 vs. 1.08 +/- 0.12 micromol/liter (P < 0.001)]. No differences in circulating DHEA, androstenedione, estradiol, or testosterone levels were found. However, in study group 2, serum estrone levels were lower in heterozygous CYP3A7*1C carriers compared with homozygous carriers of the reference allele (0.11 +/- 0.002 vs. 0.08 +/- 0.006 nmol/liter; P < 0.001).

CONCLUSION

The CYP3A7*1C polymorphism causes the persistence of enzymatic activity of CYP3A7 during adult life, resulting in lower circulating DHEAS and estrone levels.

A new polymorphism in the type II deiodinase gene is associated with circulating thyroid hormone parameters

Type II deiodinase (D2) is important in the regulation of local thyroid hormone bioactivity in certain tissues. D2 in skeletal muscle may also play a role in serum triiodothyronine (T(3)) production. In this study, we identified a polymorphism in the 5'-UTR of the D2 gene (D2-ORFa-Gly3Asp). We investigated the association of D2-ORFa-Gly3Asp, and of the previously identified D2-Thr92Ala polymorphism, with serum iodothyronine levels. D2-ORFa-Gly3Asp was identified by sequencing the 5'-UTR of 15 randomly selected individuals. Genotypes for D2-ORFa-Gly3Asp were determined in 156 healthy blood donors (age 46.3 +/- 12.2 yr) and 349 ambulant elderly men (age 77.7 +/- 3.5 yr) and related to serum iodothyronine and TSH levels. D2-ORFa-Asp(3) had an allele frequency of 33.9% in blood bank donors and was associated with serum thyroxine (T(4); Gly/Gly vs. Gly/Asp vs. Asp/Asp = 7.06 +/- 0.14 vs. 6.74 +/- 0.15 vs. 6.29 +/- 0.27 microg/dl, P = 0.01), free T(4) (1.22 +/- 0.02 vs. 1.16 +/- 0.02 vs. 1.06 +/- 0.04 ng/dl, P = 0.001), reverse T(3) (P = 0.01), and T(3)/T(4) ratio (P = 0.002) in a dose-dependent manner, but not with serum T(3) (P = 0.59). In elderly men, D2-ORFa-Asp(3) had a similar frequency but was not associated with serum iodothyronine levels. This new polymorphism in the 5'-UTR of D2 is associated with iodothyronine levels in blood donors but not in elderly men. We hypothesize that this might be explained by the decline in skeletal muscle size during aging, resulting in a relative decrease in the contribution of D2 to serum T(3) production.

A polymorphism in type I deiodinase is associated with circulating free insulin-like growth factor I levels and body composition in humans

The interaction between the GH-IGF-I axis and thyroid hormone metabolism is complex and not fully understood. T(4) stimulates IGF-I activity in animals in the absence of GH. On the other hand, GH replacement therapy results in an increase in serum T(3) and a decrease in T(4) and rT(3) levels, suggesting a stimulation of type I deiodinase (D1) activity. Recently, we demonstrated the association of two polymorphisms in D1 (D1a-C/T; T = 34%, and D1b-A/G; G = 10%) with serum iodothyronine levels. Haplotype alleles were constructed, suggesting a lower activity of the D1 haplotype 2 allele (aT-bA) and a higher activity of the haplotype allele 3 (aC-bG). In this study, we investigated whether genetic variations in D1 are associated with the IGF-I system. In 156 blood donors and 350 elderly men, the association of the D1 haplotype alleles with circulating IGF-I and free IGF-I levels was studied. In addition, potential associations with muscle strength and body composition were investigated in the elderly population. Finally, the relation between serum iodothyronine levels and IGF-I levels was studied. In blood donors, haplotype allele 2 was associated with higher levels of free IGF-I (302.9 +/- 22.9 vs. 376.3 +/- 19.1 pg/ml, P = 0.02). In elderly men, haplotype allele 2 also showed an allele dose increase in free IGF-I levels (P(trend) = 0.01) and an allele dose decrease in serum T(3) levels (P(trend) = 0.01), independent of age. Carriers of the D1a-T variant also had a higher isometric grip strength (P = 0.047) and maximum leg extensor strength (P = 0.07) as well as a higher lean body mass (P = 0.03). In blood donors, T(4) and free T(4) were negatively correlated with total IGF-I levels (R = -0.18, P = 0.03 and R = -0.24, P = 0.003), whereas T(3) to T(4) and T(3) to reverse T(3) ratios were positively correlated with total IGF-I (R = 0.31, P < 0.001 and R = 0.18, P = 0.03). Free IGF-I showed a negative correlation with T(4) (R = -0.26, P = 0.001) and T(4)-binding globulin (R = -0.31, P < 0.001) and a positive correlation with T(3) to T(4) ratio (R = 0.21, P = 0.01). In conclusion, a polymorphism that results in a decreased D1 activity is associated with an increase in free IGF-I levels. The pathophysiological significance of this association with IGF-I is supported by an increased muscle strength and muscle mass in carriers of the D1 haplotype 2 allele in a population of elderly men. The association of D1 haplotype allele 2 with serum T(3) levels in the elderly population suggests a relative increase in its contribution to circulating T(3) in old age.

Association of the ER22/23EK polymorphism in the glucocorticoid receptor gene with survival and C-reactive protein levels in elderly men

PURPOSE

We recently demonstrated that a polymorphism in codons 22 and 23 of the glucocorticoid receptor gene is associated with relative glucocorticoid resistance, greater insulin sensitivity, and lower total and low-density lipoprotein cholesterol levels. In the present study, we investigated whether the ER22/23EK polymorphism is associated with survival, cholesterol levels, and two predictors of mortality: serum C-reactive protein and interleukin 6 levels.

METHODS

We studied 402 men (mean [+/- SD] age, 77.8 +/- 3.6 years). C-reactive protein was measured by a highly sensitive method using a latex-enhanced immunoephelometric assay. Interleukin 6 was determined by a commercially available immulite assay.

RESULTS

After a follow-up of 4 years, 73 (19%) of 381 noncarriers died, while none of the 21 ER22/23EK carriers had died (P = 0.03). C-reactive protein levels were about 50% lower in ER22/23EK carriers (P = 0.01). There were no differences in interleukin 6 levels.

CONCLUSION

Carriers of the ER22/23EK polymorphism have better survival than noncarriers, as well as lower C-reactive protein levels.

Carotid Artery Plaque Burden, Stiffness, and Mortality Risk in Elderly Men

Background— Indicators of carotid atherosclerosis may confer additional prognostic value and guide clinicians in cardiovascular risk assessment. Carotid artery morphology (plaque burden) and function (stiffness indexes) as predictors of all-cause and cardiovascular mortality were prospectively evaluated in elderly men.

Methods and Results— Cardiovascular risk profile was measured in 367 independently living men (mean± SD age, 78±4 years). The number of carotid plaques was assessed by B-mode ultrasound, and arterial stiffness was quantified with a wall tracker system. During 48 months of follow-up, 70 deaths (28 cardiovascular) occurred. The total number of carotid plaques was the parameter most closely related to prognosis. In the age-adjusted multivariate Cox model, all-cause mortality was predicted by number of plaques (hazard ratio [HR] per 1-unit increase, 1.35; 95% confidence interval [CI], 1.12 to 1.64). Predictors of cardiovascular mortality in the respective model were number of plaques (HR, 1.18; 95% CI, 1.04 to 1.33) and Young’s elastic modulus (HR, 1.68; 95% CI, 1.26 to 2.26). Number of plaques improved the prognostic utility in any prognosis model when added to commonly available cardiovascular risk information. In contrast, stiffness indexes offered no consistent additive value.

Conclusions— In elderly men, carotid artery plaque burden is a strong independent predictor of all-cause and cardiovascular mortality in the years to come. The additional value of carotid artery stiffness measurements as a pathophysiologically related entity appears to be limited in this age group and, if anything, confined to cardiovascular mortality risk.

Endogenous sex hormones and progression of carotid atherosclerosis in elderly men

BACKGROUND

The burden of atherosclerosis especially afflicts the increasing older segment of the population. Recent evidence has emphasized a protective role of endogenous sex hormones in the development of atherosclerosis in aging men.

METHODS AND RESULTS

We studied the association between endogenous sex hormones and progression of atherosclerosis in 195 independently living elderly men. Participants underwent measurements of carotid intima-media thickness (IMT) at baseline in 1996 and again in 2000. At baseline, serum concentrations of testosterone (total and free) and estradiol (total and free E2) were measured. Serum free testosterone concentrations were inversely related to the mean progression of IMT of the common carotid artery after adjustment for age (beta=-3.57; 95% CI, -6.34 to -0.80). Higher serum total and free E2 levels were related to progression of IMT of the common carotid artery after adjustment for age (beta=0.38; 95% CI, -0.11 to 0.86; and beta=0.018; 95% CI, -0.002 to 0.038, respectively). These associations were independent of body mass index, waist-to-hip ratio, presence of hypertension and diabetes, smoking, and serum cholesterol levels

CONCLUSIONS

Low free testosterone levels were related to IMT of the common carotid artery in elderly men independently of cardiovascular risk factors.

Identification of the BclI polymorphism in the glucocorticoid receptor gene: association with sensitivity to glucocorticoids in vivo and body mass index

OBJECTIVE

Sensitivity to glucocorticoids differs between individuals, partially due to genetic variation in the glucocorticoid receptor (GR) gene. We studied the sequence alteration of a previously described intronic BclI polymorphism of the GR gene, and investigated whether there was an association with sensitivity to glucocorticoids and anthropometric parameters in a group of healthy elderly individuals.

DESIGN AND MEASUREMENTS

In study group 1, two overnight dexamethasone suppression tests (DSTs) were performed: with 1 mg dexamethasone, and 2.5 years later with 0.25 mg dexamethasone. Anthropometric parameters were measured in a larger population (study group 2), as well as in a third study group, in which we also measured body composition by dual-energy X-ray absorbtiometry (DEXA) scans.

SUBJECTS

Groups 1 and 2, respectively, 191 and 1963 male and female participants of the Rotterdam study, a population-based study in Dutch elderly. Study group 3: 370 elderly males (mean age 77.8 +/- 0.2 years) from Zoetermeer, the Netherlands.

RESULTS

We identified the BclI restriction site polymorphism as a C/G substitution in intron 2, 646 nucleotides downstream from exon 2. After both 1 mg and 0.25 mg DST, heterozygous (CG) and homozygous G-allele carriers (GG) had lower cortisol levels than CC-carriers (P = 0.01 and P = 0.02, respectively). In study group 2, we found a lower body mass index (BMI; P = 0.006) and waist-hip ratio (WHR; P = 0.02) in G-allele carriers. In study group 3, again we found a lower BMI (P = 0.05) in G-allele carriers. No differences were found in fat mass. However, lean mass tended to be lower in G-allele carriers (P = 0.07).

CONCLUSIONS

We characterized a BclI-RFLP (restriction fragment length polymorphism) of the GR gene as a C/G polymorphism in intron 2 of which the G-allele was associated with hypersensitivity to glucocorticoids. This resulted in a lower BMI in older individuals in general, while our study in elderly males suggests that the lower BMI is probably due to a greater loss of lean mass during the ageing process.

Sex hormones and male health: effects on components of the frailty syndrome

Physicians are seeing an increasing number of older male patients with chronic diseases and conditions. However, the potential relevance of low levels of circulating endogenous androgens in connection with these diseases and conditions is generally poorly understood. Research findings have suggested that androgens play a distinct role in bone metabolism, body composition such as muscle and fat mass and fat distribution, cognitive functioning, mood and well being. The aim of this paper is to summarize the currently available data on the association between endogenous androgens and the intermediate or clinically manifest indicators of chronic conditions in men that might contribute to the phenomenon "frailty". The evidence that reductions in endogenous androgens play a role in age-related health problems is circumstantial. Therefore, large-scale randomized trials are needed to establish whether aging males with low serum androgen levels benefit from androgen supplementation.

Serum insulin-like growth factor binding protein-2 levels as an indicator of functional ability in elderly men

BACKGROUND

In a cross-sectional study in 403 healthy, independently living elderly men (mean age 78 years), we determined which are the main physiological determinants of functional ability in the elderly, and which components of the somatotropic system contribute to the maintenance of functional ability.

METHODS

Functional ability was assessed by the number of problems in activities of daily living and by a measure of physical performance. Other physical characteristics included leg extensor strength, bone mineral density of total body and proximal femur, and body composition, including lean mass and fat mass. Serum insulin-like growth factor (IGF)-I and its binding proteins (IGFBP) -1, -2 and -3 concentrations were all measured by RIA.

RESULTS

Muscle strength was related to a lower degree of disability. Further, it was positively related to physical performance and bone mineral density (all P<0.001). Fat mass influenced activities of daily living and physical performance negatively and bone mineral density positively (all P<0.001). Serum concentrations of IGF-I and IGFBP-3 were not related to any of the physical characteristics. High serum IGFBP-2 concentrations were related to a higher degree of disability (P<0.001), a lower physical performance (P=0.006), muscle strength (P=0.002), bone mineral density of proximal femur (P=0.007), lean mass and fat mass (both P<0.001). Serum insulin and IGFBP-1 concentrations were independently, positively related to lean mass (P=0.003) and fat mass (P<0.001).

CONCLUSIONS

In independently living elderly men, functional ability appears to be determined by muscle strength (positive) and fat mass (negative). Low serum IGFBP-2 concentrations are a powerful indicator for overall good physical functional status, probably inversely reflecting the integrated sum of nutrition and the biological effects of growth hormone, IGF-I and insulin.

Endocrine aspects of healthy ageing in men

Frailty is characterized by generalized weakness, impaired mobility and balance and poor endurance. Loss of muscle strength is an important factor in the process of frailty, and is the limiting factor for an individual's chances of living an independent life until death. In men, several hormonal systems show a decline in activity during ageing. Serum bioavailable testosterone and oestradiol, dehydroepiandrosterone and its sulfate, and growth hormone and insulin-like growth factor 1 concentrations all decrease during ageing in men. Physical changes during ageing have been considered physiologic, but there is evidence that some of these changes are related to this decline in hormonal activity. Studies on hormone administration in the elderly appear to be promising. However, until now, hormone replacement has not yet been proven to be beneficial and safe.