Association of serum phosphate levels with glucose tolerance, insulin sensitivity and insulin secretion in non-diabetic subjects

Cholecalciferol ameliorates insulin signalling and insulin regulation of enzymes involved in glucose metabolism in the rat heart

CONTEXT

The evidence on potential cross-talk of vitamin D and insulin in the regulation of cardiac metabolism is very scanty.

OBJECTIVE

Cholecalciferol was administered to male Wistar rats for six weeks to study its effects on cardiac glucose metabolism regulation.

MATERIALS AND METHODS

An expression, phosphorylation and/or subcellular localisation of insulin signalling molecules, glucose transport and metabolism key proteins were studied.

RESULTS

Circulating non-esterified fatty acids (NEFA) level was lower after cholecalciferol administration. Cholecalciferol decreased cardiac insulin receptor substrate 1 Ser307 phosphorylation, while insulin-stimulated Akt Thr308 phosphorylation was increased. Cardiac 6-phosphofructo-2-kinase protein, hexokinase 2 mRNA level and insulin-stimulated glycogen synthase kinase 3β Ser9 phosphorylation were also increased. Finally, FOXO1 transcription factor cytosolic level was reduced.

CONCLUSION

Vitamin D-related improvement of insulin signalling and insulin regulation of glucose metabolism in the rat heart is accompanied by the decrease of blood NEFA level and dysregulation of cardiac FOXO1 signalling.

Diuretic Use and Serum Phosphate: Rotterdam Study and UK Biobank

Purpose

Hypophosphatemia (serum phosphate < 0.80 mmol/L) leads to musculoskeletal complaints. The most common drugs linked to hypophosphatemia are thiazide and loop diuretics, but studies in the general population are lacking. Our aim was to study associations between diuretic use and serum phosphate in the Rotterdam Study (RS), a population-based cohort study, with replication in UK Biobank (UKBB).

Methods

Associations between thiazide and loop diuretic use and serum phosphate and odds of hypophosphatemia were analyzed with cross-sectional multivariate linear and logistic regression in participants without chronic kidney disease in the RS and UKBB. Analyses were adjusted for age, sex, and body mass index (BMI) and pooled in 3 RS cohorts with further adjustment for cohort and serum potassium, which was not available in UKBB.

Results

Thiazide diuretics were associated with lower serum phosphate in both sexes. This association lost significance in RS females after adjustment for BMI and in males after adjustment for serum potassium. Thiazide diuretics increased odds of hypophosphatemia in females in both cohorts and in males in UKBB only. Loop diuretics were associated with lower serum phosphate in females but not males. Adjustment for BMI attenuated these associations. Associations between loop diuretics and increased odds of hypophosphatemia in females lost significance after BMI adjustment.

Conclusion

Thiazides, but not loop diuretics, and increased BMI and decreased serum potassium should be considered as contributing factors in subjects with hypophosphatemia. Further studies are needed to replicate the findings and elucidate the potential role of hypokalemia as a mediator of this effect.

Calcium-phosphate homeostasis and insulin resistance in men

BACKGROUND AND AIMS

Data on P homeostasis in insulin resistance (IR) are still conflicting. We investigated calcium-phosphate homeostasis parameters in men with/without IR.

METHODS AND RESULTS

177 volunteers (aged 61.62 ± 12.11), whose body mass index (BMI) was 29.97 ± 6.35, were studied. On fasting blood and spot urine samples, we measured serum creatinine, sodium (sNa), potassium (sK), chloride (sCl), calcium (sCa), phosphate (sP), alkaline phosphatase total activity (ALP), glucose, insulin, parathyroid hormone (PTH), 25-hydroxy-vitamin D [25(OH)D], and urinary electrolytes corrected for creatinine (uNa/Cr, uK/Cr, uCl/Cr, uCa/Cr, and uP/Cr). Through the QUICKI index, we separated subjects with (IR+, n = 68) or without (IR-, n = 109) IR, and their parameters were compared. Associations were assessed by age-adjusted partial correlation, whose coefficients were compared by Fisher's transform. IR + had higher sP (3.54 ± 0.65 vs. 3.35 ± 0.47, p = 0.044) and lower uCa/Cr levels (0.073 ± 0.056 vs. 0.095 ± 0.072, p = 0.047) than IR-. BMI correlated with sP (r = 0.21, p < 0.05) and PTH (r = 0.29, p < 0.01). QUICKI negatively correlated with sCa (r = -0.22, p < 0.05) and positively with uCa/Cr (r = 0.21, p < 0.05), in turn correlating with uNa/Cr (r = 0.45, p < 0.001). In both groups, uCa/Cr correlated with eGFR and uNa/Cr (p < 0.05 to p < 0.001). In IR + only, sP correlated with BMI, PTH with insulin, and uP/Cr (p < 0.05 for all). IR+ and IR-coefficients differed (p < 0.05 to p < 0.001) for the correlation of sP with BMI and of PTH with insulin and uP/Cr.

CONCLUSION

The higher sP and lower uCa/Cr levels found in men with IR + suggest that IR could modulate calcium-phosphate homeostasis, likely by affecting their renal handling.

Endocrine FGFs and their signaling in the brain: Relevance for energy homeostasis

Since their discovery in 2000, there has been a continuous expansion of studies investigating the physiology, biochemistry, and pharmacology of endocrine fibroblast growth factors (FGFs). FGF19, FGF21, and FGF23 comprise a subfamily with attributes that distinguish them from typical FGFs, as they can act as hormones and are, therefore, referred to as endocrine FGFs. As they participate in a broad cross-organ endocrine signaling axis, endocrine FGFs are crucial lipidic, glycemic, and energetic metabolism regulators during energy availability fluctuations. They function as powerful metabolic signals in physiological responses induced by metabolic diseases, like type 2 diabetes and obesity. Pharmacologically, FGF19 and FGF21 cause body weight loss and ameliorate glucose homeostasis and energy expenditure in rodents and humans. In contrast, FGF23 expression in mice and humans has been linked with insulin resistance and obesity. Here, we discuss emerging concepts in endocrine FGF signaling in the brain and critically assess their putative role as therapeutic targets for treating metabolic disorders.

Effect of vitamin D on regression to normal glucose regulation and individual glycemic measures: A secondary analysis among participants adherent to the trial protocol in the randomized clinical trial vitamin D and type 2 diabetes (D2d) study

AIMS

To examine the effect of vitamin D on regression to normal glucose regulation (NGR) and individual glycemic measures in the D2d study.

METHODS

In per-protocol analyses, we examined time to new-onset diabetes; time to new-onset NGR defined as first occurrence of: 2-or-3 glycemic criteria in the normal range (NGR-1) or fasting plasma glucose (FPG) and 2-hour post-load-glucose (2hPG) in the normal range (NGR-2); proportion meeting NGR at the last study visit; and change in FPG, 2hPG, and HbA1c.

RESULTS

Among 2423 participants, hazard ratio [HR] for diabetes was 0.84 [95%CI, 0.71, 0.99]). HR (95%CI) was 1.16 (0.99, 1.36) for new-onset NGR-1 and 1.06 (0.87, 1.30) for NGR-2. At the last visit, NGR-1 occurred in 12.4% vs. 9.5% participants in the vitamin D vs. placebo group (rate ratio for vitamin D 1.31 [1.02, 1.70]); whereas, NGR-2 occurred in 8.7% vs. 6.0% (rate ratio for vitamin D 1.45 [1.05, 2.00]). During follow-up, FPG, HbA1c, and 2hPG increased in both groups. Mean difference in FPG favored vitamin D (-0.80 mg/dL; 95%CI, -1.26, -0.33).

CONCLUSIONS

In secondary analyses among participants adherent to the trial protocol, vitamin D lowered risk of developing diabetes and increased likelihood of NGR at the end of the study.

Association Between Primary Hyperparathyroidism and Secondary Diabetes Mellitus: Findings From a Scoping Review

An ill-defined association exists between diabetes mellitus (insulin resistance) and primary hyperparathyroidism. This article explores this phenomenon while providing an explanation for such a relationship and reviewing the evidence regarding the response to insulin sensitivity following a parathyroidectomy. Primary hyperparathyroidism may increase the risk of developing insulin resistance; peculiarly, this is not present in all patients. It is likely that both intracellular hypercalcemia and hypophosphatemia alter the insulin receptor expression and response; the contribution of parathyroid hormone is less clear. Following parathyroidectomy, patients may demonstrate improvement in their insulin sensitivity, while others have no response or a detrimental effect. A varied phenotype exists among patients, and furthermore, it is unclear why certain patients demonstrate improvement in insulin sensitivity following a parathyroidectomy, whereas others fail to do so. While this review provides a broad overview of the general endocrine community, it is imperative to note that clinical applicability is limited until further studies address these remaining uncertainties. Due to the lack of understanding regarding this endocrinological enigma, the presence of insulin resistance, at this present time, should not be a criterion for a parathyroidectomy.

Interaction between inorganic phosphate concentration and glucose metabolism in mild refeeding syndrome model

Refeeding syndrome is a major clinical problem that leads to fatal complications in patients suffering from malnutrition. Hypophosphatemia inevitably is observed at the onset of refeeding syndrome and therefore is monitored during refeeding; however, the causes of metabolic changes in phosphate concentration during refeeding remain poorly understood. In a previous study, we established a refeeding syndrome model employing total parenteral nutrition with insulin-induced hypophosphatemia, but the symptoms were severe and the metabolic mechanisms in this model may not have been representative of clinical conditions. Therefore, we established a new animal model of mild refeeding syndrome by using a shorter fasting period followed by a single refeeding. These mild refeeding syndrome-model rats exhibited hypophosphatemia without increases in urinary phosphate excretion. Interestingly, administration of the combination of phosphate and insulin during refeeding promoted insulin secretion during refeeding. This model implies that Pi may directly promote insulin secretion in pancreatic cells. These results clarify the interaction between phosphate and glucose metabolism pancreatic cells during refeeding syndrome in a mild refeeding syndrome model.

Dietary Strawberries Improve Serum Metabolites of Cardiometabolic Risks in Adults with Features of the Metabolic Syndrome in a Randomized Controlled Crossover Trial

Dietary strawberries have been shown to improve cardiometabolic risks in multiple clinical trials. However, no studies have reported effects on serum metabolomic profiles that may identify the target pathways affected by strawberries as underlying mechanisms. We conducted a 14-week randomized, controlled crossover study in which participants with features of metabolic syndrome were assigned to one of the three arms for four weeks separated by a one-week washout period: control powder, 1 serving (low dose: 13 g strawberry powder/day), or 2.5 servings (high dose: 32 g strawberry powder/day). Blood samples, anthropometric measures, blood pressure, and dietary and physical activity data were collected at baseline and at the end of each four-week phase of intervention. Serum samples were analyzed for primary metabolites and complex lipids using different mass spectrometry methods. Mixed-model ANOVA was used to examine differences in the targeted metabolites between treatment phases, and LASSO logistic regression was used to examine differences in the untargeted metabolites at end of the strawberry intervention vs. the baseline. The findings revealed significant differences in the serum branched-chain amino acids valine and leucine following strawberry intervention (high dose) compared with the low-dose and control phases. Untargeted metabolomic profiles revealed several metabolites, including serum phosphate, benzoic acid, and hydroxyphenyl propionic acid, that represented improved energy-metabolism pathways, compliance measures, and microbial metabolism of strawberry polyphenols, respectively. Thus, dietary supplementation of strawberries significantly improves the serum metabolic profiles of cardiometabolic risks in adults.

Prognostic Significance of Baseline Blood Glucose Levels and Glucose Variability in Severe Acute Kidney Injury: A Secondary Analysis from the RENAL Study

Aim: To study the associations between baseline blood glucose levels (BGL), glycemic variability and clinical outcomes in patients with severe acute kidney injury (AKI) receiving continuous renal replacement therapy (CRRT). Methods: We performed a secondary analysis of the Randomized Evaluation of Normal versus Augmented Level of RRT (RENAL) study. A multivariate Cox regression model was used to assess the association between baseline BGL, glycemic variability and clinical outcomes. The primary outcome was all-cause mortality, and secondary outcomes were duration of hospital and intensive care unit (ICU) stay. Results: Baseline BGL data were available in 1404 out of 1508 patients from the RENAL study. Among them, 627 patients died within 90 days of randomization. Compared to patients in the second quartile (BGL 5.8−7.2 mmol/L), patients in the first quartile (BGL < 5.8 mmol/L) had increased mortality rate (90-day HR 1.48; p = 0.001; 28-day HR 1.47; p = 0.042). However, there were no significant differences in ICU and hospital length of stay (LOS) (p = 0.82 and p = 0.33, respectively). Glycemic variability data were from 1345 out of 1404 patients who had data for BG values within 28 days. Higher coefficient of variation (CV) (HR 1.02; P trend = 0.002) and standard deviation value (SD) (HR 1.29; P trend = 0.027) were associated with higher risk of death at day 90. Conclusions: We identified a low BGL within the normal physiological range at baseline and greater CV and SD values as significant modifiable risk factors for mortality in severe AKI patients in ICU, which may be a target for intervention.

A Review of Current Evidence on the Relationship between Phosphate Metabolism and Metabolic Syndrome

Phosphorus, present as phosphate in biological systems, is an essential mineral for various biological activities and biochemical processes. Numerous studies have indicated that disturbed phosphate balance may contribute to the development of metabolic syndrome (MetS). However, no consistent result was found on the association between phosphorus intake and serum phosphate concentration with MetS. It is believed that both positive and negative impacts of phosphorus/phosphate co-exist in parallel during MetS condition. Reduced phosphate level contributed to the development of obesity and hyperglycaemia. Low phosphate is believed to compromise energy production, reduce exercise capacity, increase food ingestion, and impair glucose metabolism. On the other hand, the effects of phosphorus/phosphate on hypertension are rather complex depending on the source of phosphorus and subjects' health conditions. Phosphorus excess activates sympathetic nervous system, renin-angiotensin-aldosterone system, and induces hormonal changes under pathological conditions, contributing to the blood pressure-rising effects. For lipid metabolism, adequate phosphate content ensures a balanced lipid profile through regulation of fatty acid biosynthesis, oxidation, and bile acid excretion. In conclusion, phosphate metabolism serves as a potential key feature for the development and progression of MetS. Dietary phosphorus and serum phosphate level should be under close monitoring for the management of MetS.

Phosphate Dysregulation and Metabolic Syndrome

Phosphorus is one of the most abundant minerals in the human body. It is essential for almost all biochemical activities through ATP formation, intracellular signal transduction, cell membrane formation, bone mineralization, DNA and RNA synthesis, and inflammation modulation through various inflammatory cytokines. Phosphorus levels must be optimally regulated, as any deviations may lead to substantial derangements in glucose homeostasis. Clinical studies have reported that hyperphosphatemia can increase an individual's risk of developing metabolic syndrome. High phosphate burden has been shown to impair glucose metabolism by impairing pancreatic insulin secretion and increasing the risk of cardiometabolic disorders. Phosphate toxicity deserves more attention as metabolic syndrome is being seen more frequently worldwide and should be investigated further to determine the underlying mechanism of how phosphate burden may increase the cardiometabolic risk in the general population.

Impact of Obesity on Bone Metabolism in Children

Obesity is an epidemic disease that can increase the incidence of type 2 diabetes, cardiovascular disease, malignancy, hypertension, and other health problems that affect the musculoskeletal system. There is a complex interaction between obesity and bone metabolism. In children with obesity, the peroxisome proliferator-activated receptor gamma pathway causes the differentiation of mesenchymal stem cells into adipocytes via osteoblasts, in which results in low bone mass and osteoporosis. Systemic inflammation in obesity has negative effects on bone metabolism. An increase in the number and size of adipose tissue and adipocytokines secreted from adipocytes affect the bone mass of the whole body with hormonal and biochemical effects. The skeletal effects of obesity are mediated by higher oxidative stress and increased production of proinflammatory cytokines. Osteoporosis due to obesity has increased morbidity and mortality in recent years, resulting in important health problems in developed and developing countries.

Chronic High Phosphate Intake in Mice Affects Macronutrient Utilization and Body Composition

SCOPE

In the last decades, dietary phosphate intake has increased due to a higher consumption of processed food. This higher intake has an impact on body composition and health state. Recently, we found that a high chronic phosphate diet leads to no major renal alterations, but negatively affects parameters of bone health probably due to the chronic acid load. Here we assessed the effect of high phosphate consumption on parameters of energy metabolism.

METHODS AND RESULTS

Healthy mature adult mice were fed for 1 year or four months with either a standard (0.6 % w/w) or a high phosphate (1.2 % w/w) diet. Males and females of two different genetic backgrounds were investigated. Mice fed the high phosphate diet showed an attenuated body-weight gain, lower respiratory exchange ratio, decreased body fat mass and increased lean-to-fat mass ratio. Moreover, the high phosphate diet led to fasting hypoglycemia with no differences in the glucose response to an oral glucose tolerance test. Triglycerides and cholesterol in blood were similar independently of dietary phosphate content. However, 1-methylhistidine was lower in animals fed a chronic high phosphate intake.

CONCLUSIONS

High phosphate diet attenuates body weight gain, but induces hypoglycaemia and may alter muscle homeostasis. This article is protected by copyright. All rights reserved.

The Role of Bone-Derived Hormones in Glucose Metabolism, Diabetic Kidney Disease, and Cardiovascular Disorders

Bone contributes to supporting the body, protecting the central nervous system and other organs, hematopoiesis, the regulation of mineral metabolism (mainly calcium and phosphate), and assists in respiration. Bone has many functions in the body. Recently, it was revealed that bone also works as an endocrine organ and secretes several systemic humoral factors, including fibroblast growth factor 23 (FGF23), osteocalcin (OC), sclerostin, and lipocalin 2. Bone can communicate with other organs via these hormones. In particular, it has been reported that these bone-derived hormones are involved in glucose metabolism and diabetic complications. Some functions of these bone-derived hormones can become useful biomarkers that predict the incidence of diabetes and the progression of diabetic complications. Furthermore, other functions are considered to be targets for the prevention or treatment of diabetes and its complications. As is well known, diabetes is now a worldwide health problem, and many efforts have been made to treat diabetes. Thus, further investigations of the endocrine system through bone-derived hormones may provide us with new perspectives on the prediction, prevention, and treatment of diabetes. In this review, we summarize the role of bone-derived hormones in glucose metabolism, diabetic kidney disease, and cardiovascular disorders.

Acute Effects of an Inorganic Phosphorus Additive on Mineral Metabolism and Cardiometabolic Risk Factors in Healthy Subjects

CONTEXT

Hyperphosphatemia and high levels of fibroblast growth factor 23 (FGF23) are risk factors for cardiovascular events in patients with chronic kidney diseases. However, the impact of an inorganic phosphorus additive in healthy people is largely unknown.

OBJECTIVE

We aimed to investigate the acute effect of excessive dietary phosphorus administered as sodium dihydrogen phosphate on the postprandial levels of Pi and FGF23 and the response to food.

METHODS

This study was a double-blind placebo-controlled crossover study with 29 healthy male and female participants from the general community who were administered a single dose of either 700 mg phosphorus (NaH2PO4) or a sodium-adjusted placebo in combination with a test meal. Postprandial plasma levels of Pi and FGF23 were measured.

RESULTS

Compared with placebo, oral phosphorus increased the plasma Pi level, which remained elevated during the ensuing 8 hours (at 480 minutes: 1.31 vs 1.16 mmol/l; P < 0.001), increased urinary Pi (iAUC0-480 789 vs 95 mmol/mmol; P < 0.001), reduced tubular Pi reabsorption (iAUC0-480 -31.5 vs -6.2; P < 0.001), decreased urinary calcium (iAUC0-240 30.6 vs 53.0 mmol/mmol; P = 0.009), and stimulated the release of parathyroid hormone (iAUC0-480 2212 vs 768 ng/l; P < 0.001). However, the FGF23 levels did not change. Postprandial levels of glucose, insulin, and lipids were not substantially affected by phosphorus vs placebo.

CONCLUSION

An oral phosphorus load can induce elevated postprandial levels of circulating Pi for hours in healthy subjects, despite rapid homeostatic counterreactions. FGF23 levels and the postprandial response to food were not affected.

Sex-Specific Associations Between Serum Phosphate Concentration and Cardiometabolic Disease: A Cohort Study on the Community-Based Older Chinese Population

PURPOSE

This study aimed to investigate the association between sex-specific baseline serum phosphate and the incidence of new-onset cardiometabolic disease in a cohort of Shanghai-based older Chinese individuals.

PATIENTS AND METHODS

A community cohort of 5000 disease-free Chinese men and women was recruited in 2013 and followed until 2017 for the development of cardiometabolic disease. Participants underwent index and follow-up health screens at the Tongji Medical School affiliated Shanghai East Hospital, including blood biochemistry analysis, anthropometric measurements, interview on health-related behaviors, and clinical evaluation.

RESULTS

Higher baseline serum phosphate (>1.25 mmol/L) was significantly associated with new-onset type-2 diabetes mellitus (HR 1.730, 95% CI 1.127-2.655) and metabolic syndrome (HR 0.640, 95% CI 1.085-2.155) in women. Baseline serum phosphate was associated with age, BMI, waist circumference, SBP, total calcium, bicarbonate, and total cholesterol in women. The estimated risk of developing diabetes mellitus in women with inorganic phosphate >1.25 mmol/L was 14.54%. Inorganic phosphate accounted for 9.2% of the variance explained in a total estimated 14.52% of variance attributed to BMI, total cholesterol, total calcium, waist circumference, and inorganic phosphate.

CONCLUSION

Serum phosphate concentration showed sex-specific associations with diabetes and metabolic syndrome. Higher inorganic phosphate was associated with increased risk of developing diabetes mellitus in women. These findings may be important in the assessment of individualized metabolic risk.

The Emerging Role of Bone-Derived Hormones in Diabetes Mellitus and Diabetic Kidney Disease

Diabetic kidney disease (DKD) causes the greatest proportion of end-stage renal disease (ESRD)-related mortality and has become a high concern in patients with diabetes mellitus (DM). Bone is considered an endocrine organ, playing an emerging role in regulating glucose and energy metabolism. Accumulating research has proven that bone-derived hormones are involved in glucose metabolism and the pathogenesis of DM complications, especially DKD. Furthermore, these hormones are considered to be promising predictors and prospective treatment targets for DM and DKD. In this review, we focused on bone-derived hormones, including fibroblast growth factor 23, osteocalcin, sclerostin, and lipocalin 2, and summarized their role in regulating glucose metabolism and DKD.

Serum Phosphate, BMI, and Body Composition of Middle-Aged and Older Adults: A Cross-Sectional Association Analysis and Bidirectional Mendelian Randomization Study

BACKGROUND

Observational studies have reported associations between serum phosphate and BMI in specific clinical settings, but the nature of this relation in the general population is unclear.

OBJECTIVES

The aim of this study was twofold: to investigate the association between serum phosphate and BMI and body composition, as well as to explore evidence of causality through a bidirectional one-sample Mendelian randomization (MR) in the population-based Rotterdam Study (RS).

METHODS

Observational associations between phosphate (mg/dL) and BMI, lean mass, and fat percentage (fat%), estimated by DXA, were analyzed using multivariable regression models in 9202 participants aged 45-100 y from 3 RS cohorts. The role of serum leptin was examined in a subgroup of 1089 participants. For MR analyses, allele scores with 6 single-nucleotide polymorphisms (SNPs) for phosphate and 905 SNPs for BMI were constructed in 7983 participants.

RESULTS

Phosphate was inversely associated with BMI in the total population (β: -0.89; 95% CI: -1.17, -0.62), and stronger in women (β: -1.92; 95% CI: -2.20, -1.65) than in men (β: -0.37; 95% CI: -0.68, -0.06) (P-interaction < 0.05). Adjustment for leptin did not change results in men. In women, adjustment for leptin attenuated the association, but it was not abolished (β: -0.94; 95% CI: -1.45, -0.42). Phosphate was inversely associated with fat%, but not with lean mass, in both sexes. MR analyses suggested a causal effect of BMI on serum phosphate (β: -0.01; 95% CI: -0.02, 0.00) but not vice versa.

CONCLUSIONS

Serum phosphate was inversely associated with BMI and fat% in a population-based study of middle-aged and older adults, with a stronger effect in women than in men. Adjusting for leptin attenuated this relation in women only. MR results suggest a causal effect of BMI on phosphate but not vice versa. An underlying sex dimorphism in phosphate homeostasis should be further explored.

Effects of Periodic Religious Fasting for Decades on Nutrient Intakes and the Blood Biochemical Profile

The aim of the present study was to examine differences and correlations in nutrient intakes and serum parameters related to nutrient intake (lipid profile, vitamins, and trace elements) in 200 lifelong Christian Orthodox Church (COC) fasters with periodic abstinence from certain foods (predominantly of animal origin) for approximately half of the year and 200 non-fasting controls, all of whom did not take dietary supplements. Nutrient intakes were assessed through three-day dietary recalls. Blood samples were drawn for the analysis of potential biomarkers of nutrient intake. Fasters had lower energy intake, due to lower fat and protein intake, compared to non-fasters (p < 0.05). Fasters also had lower intakes of vitamins A, B₁, B₂, B₆, B₁₂, D, folate, pantothenate, sodium, calcium, zinc, and phosphorus. Most participants (in both groups) did not meet the recommended dietary allowances of most vitamins and elements. Most serum biochemical parameters did not reflect the differences in nutrient intakes between groups, and none exhibited a correlation coefficient above 0.5 with nutrient intakes. Our findings suggest that COC fasting is associated with reduced intake of many nutrients, although this does not seem to have an impact on the blood biochemical profile.

Assessment of insulin resistance in patients with primary hyperparathyroidism before and after Parathyroidectomy

Background

Primary hyperparathyroidism (PHPT) can lead to renal and skeletal disorders, as well as insulin resistance and impaired glucose metabolism. The current study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with PHPT.

Materials and Methods

The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy who were referred to the endocrinology clinics of Mashhad University of Medical Sciences. Thereafter, the demographic characteristics of the patients were recorded. Blood tests, including haemoglobin A1c (HbA1c), fasting blood glucose (FBG) and insulin levels, were assessed one week before and three months after the surgery. The insulin resistance score (HOMA‐IR) was calculated and compared using the relevant formula.

Results

A total of 65 participants with a mean age of 45.44 ± 9.59 years were included in the current study. In one‐month postoperative tests, mean scores of FBG (p < .05), insulin level (p < .05) and HbA1c (p < .05) were significantly reduced. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery.

Conclusion

According to our findings, parathyroidectomy can be effective in the reduction of insulin resistance and corresponding complications in patients with PHPT in the present short‐term study. However, it has yet to be confirmed as a treatment method for insulin resistance in these patients. Future long‐term studies are required to be done to investigate the effect of parathyroidectomy on insulin resistance.

The present study aimed to assess the effects of parathyroidectomy on insulin resistance in patients with primary hyperparathyroidism (PHPT). The present study was conducted on 65 patients with PHPT and indications for parathyroidectomy. Demographic characteristics of the patients were recorded. Blood tests, including fasting blood sugar (FBS), haemoglobin A1c (HbA1c) and insulin levels, were assessed one week before and three months after the surgery. The Homeostatic Model Assessment for Insulin Resistance (HOMA‐IR index) was calculated. In one‐month postoperative tests, mean scores of FBS (p < .05), insulin level (p < .05) and HbA1c (p < 0.05) were significantly reduced compared to these variables prior to the surgery. Moreover, the HOMA‐IR index decreased in 51 patients after the surgery. As evidenced by the results of the present study, parathyroidectomy can be effective in reducing insulin resistance and its complications in patients with primary hyperparathyroidism (PHPT).

Phosphate and fibroblast growth factor 23 in diabetes

Diabetes is associated with a strongly elevated risk of cardiovascular disease, which is even more pronounced in patients with diabetic nephropathy. Currently available guideline-based efforts to correct traditional risk factors are only partly able to attenuate this risk, underlining the urge to identify novel treatment targets. Emerging data point towards a role for disturbances in phosphate metabolism in diabetes. In this review, we discuss the role of phosphate and the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) in diabetes. We address deregulations of phosphate metabolism in patients with diabetes, including diabetic ketoacidosis. Moreover, we discuss potential adverse consequences of these deregulations, including the role of deregulated phosphate and glucose as drivers of vascular calcification propensity. Finally, we highlight potential treatment options to correct abnormalities in phosphate and FGF23. While further studies are needed to more precisely assess their clinical impact, deregulations in phosphate and FGF23 are promising potential target in diabetes and diabetic nephropathy.

Dietary Phosphorus as a Marker of Mineral Metabolism and Progression of Diabetic Kidney Disease

Phosphorus is an essential nutrient that is critically important in the control of cell and tissue function and body homeostasis. Phosphorus excess may result in severe adverse medical consequences. The most apparent is an impact on cardiovascular (CV) disease, mainly through the ability of phosphate to change the phenotype of vascular smooth muscle cells and its contribution to pathologic vascular, valvular and other soft tissue calcification. Chronic kidney disease (CKD) is the most prevalent chronic disease manifesting with the persistent derangement of phosphate homeostasis. Diabetes and resulting diabetic kidney disease (DKD) remain the leading causes of CKD and end-stage kidney disease (ESRD) worldwide. Mineral and bone disorders of CKD (CKD-MBD), profound derangement of mineral metabolism, develop in the course of the disease and adversely impact on bone health and the CV system. In this review we aimed to discuss the data concerning CKD-MBD in patients with diabetes and to analyze the possible link between hyperphosphatemia, certain biomarkers of CKD-MBD and high dietary phosphate intake on prognosis in patients with diabetes and DKD. We also attempted to clarify if hyperphosphatemia and high phosphorus intake may impact the onset and progression of DKD. Careful analysis of the available literature brings us to the conclusion that, as for today, no clear recommendations based on the firm clinical data can be provided in terms of phosphorus intake aiming to prevent the incidence or progression of diabetic kidney disease.

SARS-CoV-2: influence of phosphate and magnesium, moderated by vitamin D, on energy (ATP) metabolism and on severity of COVID-19

The use of vitamin D to reduce the severity of COVID-19 complications is receiving considerable attention, backed by encouraging data. Its purported mode of action is as an immune modulator. Vitamin D, however, also affects the metabolism of phosphate and Mg, which may well play a critical role in SARS-CoV-2 pathogenesis. SARS-CoV-2 may induce a cytokine storm that drains ATP whose regeneration requires phosphate and Mg. These minerals, however, are often deficient in conditions that predispose people to severe COVID-19, including older age (especially males), diabetes, obesity, and usage of diuretics. Symptoms observed in severe COVID-19 also fit well with those seen in classical hypophosphatemia and hypomagnesemia, such as thrombocytopenia, coagulopathy, dysfunction of liver and kidneys, neurologic disturbances, immunodeficiency, failure of heart and lungs, delayed weaning from a respirator, cardiac arrhythmia, seizures, and, finally, multiorgan failure. Deficiencies of phosphate and Mg can be amplified by kidney problems commonly observed in patients with COVID-19 resulting in their wastage into urine. Available data show that phosphate and Mg are deficient in COVID-19, with phosphate showing a remarkable correlation with its severity. In one experiment, patients with COVID-19 were supplemented with a cocktail of vitamin D₃, Mg, and vitamin B₁₂, with very encouraging results. We, thus, argue that patients with COVID-19 should be monitored and treated for phosphate and Mg deficiencies, ideally already in the early phases of infection. Supplementation of phosphate and Mg combined with vitamin D could also be implemented as a preventative strategy in populations at risk.

Prognostic value of admission serum glucose-phosphate ratio in predicting the 6-month outcome of patients with severe traumatic brain injury: A retrospective study

BACKGROUND

Serum glucose-phosphate ratio has been revealed to be associated with severity and prognosis of aneurysmal subarachnoid hemorrhage. Objective of this study was to investigate the relationship between serum glucose-phosphate ratio and severe traumatic brain injury outcome.

METHODS

Patients with severe traumatic brain injury were stratified in quartiles according to their serum glucose-phosphate ratio. Outcome parameters included mortality, overall survival and poor outcome defined as Glasgow outcome scale score of 1-3 at post-traumatic 6 months. Multiple logistic regression analysis was performed to evaluate the association between quartiles of serum glucose-phosphate ratio and outcome.

RESULTS

Data from 105 patients were retrospectively reviewed. Glasgow coma scale score declined, Glasgow outcome scale score decreased, Rotterdam computed tomography classification were raised, mortality increased, overall survival probability reduced and percentage of poor outcome rose significantly with each quartile of serum glucose-phosphate ratio. After adjusting for other confounding factors, serum glucose-phosphate ratio according to quartiles was substantially related to 6-month mortality, overall survival and poor outcome. Under receiver operating characteristic curve, serum glucose-phosphate ratio showed a significantly high prognostic predictive capability.

CONCLUSIONS

Serum glucose-phosphate ratio might be a potential variable that can reflect trauma severity and prognosis in patients with severe traumatic brain injury.

Association of Serum Calcium and Phosphate Concentrations with Glucose Metabolism Markers: The Furukawa Nutrition and Health Study

Calcium and phosphate may play an important role in cardio-metabolic abnormalities, including type 2 diabetes; however, epidemiological evidence of the association of calcium and phosphate status with glucose metabolism among Asians is limited. In the current study, we performed a cross-sectional analysis of the association of serum calcium, phosphate, and calcium–phosphate product concentrations with glucose metabolism markers among Japanese individuals. Overall, 1701 workers (aged 18–78 years) who participated in a health survey were enrolled in this study. Multivariable linear regression models were used to estimate means of homeostatic model assessment of insulin resistance (HOMA-IR), homeostatic model assessment of β-cell function (HOMA-β), and glycated hemoglobin (HbA1c). Serum calcium concentration was positively associated with HOMA-IR and HbA1c (p for trend < 0.01). Multivariable-adjusted means (95% confidence interval (CI)) of HOMA-IR for the lowest and highest quartiles of serum calcium were 0.78 (0.75–0.82) and 1.01 (0.96–1.07), respectively. The corresponding values for HbA1c were 5.24 (5.22–5.27) and 5.29 (5.26–5.32), respectively. Serum phosphate and calcium–phosphate product concentrations were inversely associated with HOMA-IR (p for trend < 0.01). Multivariable-adjusted means (95% CI) of HOMA-IR for the lowest and highest quartiles of serum phosphate were 1.04 (0.99–1.09) and 0.72 (0.69–0.76), respectively. The corresponding values for calcium–phosphate product were 1.04 (0.99–1.09) and 0.73 (0.69–0.77), respectively. The current findings suggest that higher serum calcium and lower serum phosphate concentrations are associated with IR among apparently healthy adults.

Examining the association between serum phosphate levels and leukocyte telomere length

Accelerated telomere attrition is related to various diseases, and multiple factors have been reported to influence telomere length. However, little attention has focused on the relationship between serum phosphate levels and mean telomere length. The purpose of this study was to explore the relationship between serum phosphate levels and mean telomere length in the US general population. A total of 7,817 participants from the 1999–2002 NHANES were included. The association between serum phosphate levels and mean telomere length was investigated using regression models. A remarkably positive relationship between serum phosphate levels and mean telomere length emerged after adjustments were made for covariates. The adjusted β coefficient of serum phosphate levels for mean telomere length was 0.038 (95% confidence intervals (CIs), 0.022 to 0.095, p = 0.002). A longer telomere length was observed in participants with serum phosphate levels in the highest quartiles, and a dose-dependent association was observed. Our study demonstrated that higher quartiles of phosphate had a remarkable correlation with longer telomere length.

Association between Serum Calcium and Risk of Cardiometabolic Disease among Community-dwelling Adults in Taiwan

Serum calcium, although only comprising 1% of total body calcium, is involved in intracellular signal pathways, vascular dilatation/constriction, and muscle contraction, which are crucial for insulin secretion, cholesterol catabolism, and blood pressure regulation. As far as we know, research on the relationship between serum calcium level and metabolic syndrome (MetS), diabetes, and hypertension in one longitudinal study is rare. Owing to the crucial role of serum calcium in human cardiometabolic physiology and lack of related study so far, this study aims to describe the relationship between serum calcium level and the incidence of MetS, diabetes, and hypertension. During the period 2010–2016, there are two parts to our study: cross-sectional analysis and longitudinal analysis. Logistic regression was applied for cross-sectional analysis of the association between serum calcium level or albumin-corrected calcium (ACCA) and the prevalence of MetS, diabetes, or hypertension. Receiver operating characteristic (ROC) curve analysis was used for calculating of optimal cut-off value of serum calcium and ACCA. Cox proportional regression for development of MetS, diabetes, and hypertension according to different cut-off values of serum calcium level and ACCA were conducted. At baseline, there were 27,364 participants in our study. Serum calcium level had positive association with diabetes in the total population, male, and female. ACCA level had positive association with diabetes in the total population, male, and female. In unadjusted and multivariate Cox proportional hazard models, serum calcium level was associated with increased risk of incident MetS in the total population and male. ACCA was associated with increased risk of incident MetS in the total population and male. ACCA was associated with increased risk of incident diabetes in the total population and male participants. This study describes the relationship between serum calcium level and the incidence of MetS, diabetes, and hypertension. Higher serum calcium level is associated with increased risk of MetS, diabetes, and hypertension.

Increased prevalence of overweight and obesity in children with X-linked hypophosphatemia

BACKGROUND/AIM

X-linked hypophosphatemia (XLH) is a rare disease characterized by low phosphate levels. Scientific evidence points to a link between hypophosphatemia and obesity in general population. The aim of our longitudinal observational study was to investigate the prevalence of obesity and associated factors in a large cohort of children with XLH.

PATIENTS/METHODS

We studied 172 XLH-children 5-20 years of age (113 girls/59 boys). Anthropometric parameters (weight, height, and BMI) were collected at birth and during follow-up at mean ages of 5.3, 8.2, 11.3, and 15.9 years (groups 1, 2, 3, and 4, respectively). In each group, subjects were classified based on International Obesity Taskforce (IOTF) cut off values of BMI for age and sex as overweight or obese (IOTF 25-30 or ≥30 kg/m2, respectively).

RESULTS

In each age-group, almost 1/3 of XLH-patients were classified as overweight or obese (29.4, 28.7, 27.5, and 36.7% in groups 1, 2, 3, and 4, respectively). Children without a XLH-family history had higher BMI-IOTF at every point of follow-up, compared to those with positive XLH-family history. Similarly, higher BMI-IOTF was significantly associated with treatment duration (23.3 ± 4.4 vs 23.8 ± 3.8 vs 25.2 ± 4.5 kg/m2, for subjects with treatment duration of <5, 5-10 and >10 years, respectively, P for trend = 0.025). Multiple regression analysis confirmed an association of treatment duration and lack of XLH-family history with higher BMI-IOTF.

CONCLUSION

One out of three of XLH-children have phenotypically unfavourable metabolic profile expressed as increased prevalence of overweight or obesity in comparison to general population. Both the lack of XLH family history and the duration of treatment increase the risk of higher BMI-IOTF. BMI should be carefully monitored in children, and later in adults, with XLH.

Management of X-linked hypophosphatemia in adults

X-linked hypophosphatemia (XLH) is caused by mutations in the PHEX gene which result in Fibroblast Growth Factor-23 (FG-F23) excess and phosphate wasting. Clinically, XLH children present with rickets, bone deformities and short stature. In adulthood, patients may still be symptomatic with bone and joint pain, osteomalacia-related fractures or pseudofractures, precocious osteoarthrosis, enthesopathy, muscle weakness and severe dental anomalies. Besides these musculoskeletal and dental manifestations, adult XLH patients are also prone to secondary and tertiary hyperparathyroidism, cardiovascular and metabolic disorders. Pathophysiology of hyperparathyroidism is only partially understood but FGF23 excess and deficient production of calcitriol likely contributes to its development. Similarly, the pathophysiological mechanisms of potential cardiovascular and metabolic involvements are not clear, but FGF-23 excess may play an essential role. Treatment should be considered in symptomatic patients, patients undergoing orthopedic or dental surgery and women during pregnancy and lactation. Treatment with oral phosphate salts and active vitamin D analogs has incomplete efficacy and potential risks. Burosumab, a recombinant human monoclonal antibody against FGF-23, has proven its efficacy in phase 2 and phase 3 clinical trials in adult patients with XLH, but currently its position as first line or second line treatment differ among the countries.

A Case of Multifactorial Diabetic Ketoacidosis Acquired in the Intensive Care Unit: A Case Report

Diabetic ketoacidosis (DKA) is a potentially fatal endocrine emergency resulting from uncontrolled diabetes mellitus (DM). The development of DKA has been linked to a number of precipitating factors such as infectious process, ischemia, medications, and other medical-surgical illnesses. These factors have been found to aggravate or unmask pre-existing glucose dysregulation secondary to absolute or relative insulin deficiency and increased levels of counter-regulatory hormones. We describe the case of a 61-year-old male with a history of insulin dependent DM who develops DKA postoperatively after a three-vessel coronary artery bypass surgery and mitral valve repair while in the intensive care unit (ICU). The patient’s postoperative course was complicated by presumed pneumonia and hyperactive delirium. On postoperative day (POD) five, the patient’s insulin infusion was held due to non-symptomatic hypoglycemia. Eleven hours later, the insulin infusion was resumed to treat DKA after laboratory findings revealed hyperglycemia, an elevated β-hydroxybutyrate, and anion gap metabolic acidosis. Multiple contributing factors for the development of DKA are suspected and discussed. It is paramount that clinicians are knowledgeable of the multiple factors that can contribute to the development of DKA in the ICU.

Association of Admission Serum Glucose-Phosphate Ratio with Severity and Prognosis of Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Serum hyperglycemia and hypophosphatemia have been reported to be common in patients with aneurysmal subarachnoid hemorrhage (aSAH). This study aimed to explore whether admission serum glucose-phosphate ratio was associated with the severity and prognosis of aSAH.

METHODS

We retrospectively analyzed 198 patients with aSAH who were admitted within 24 hours of hemorrhage to a single academic hospital from June 2016 to September 2017. The following determinations were recorded: aSAH severity on admission, assessment by the World Federation of Neurosurgical Societies grading scale (WFNS), Fisher score defined according to the computed tomography results, and 3-month outcome assessed by the Glasgow Outcome Scale. A statistical analysis of the clinical and laboratory risk factors of poor outcome was conducted.

RESULTS

Admission serum glucose-phosphate ratio was increased in a WFNS grade-dependent manner and was higher in patients who had a poor outcome than in those who had a good outcome 3 months after aSAH. Multiple binomial logistic regression analysis showed that serum glucose-phosphate ratio, along with age, WFNS grade, and intraventricular hemorrhage, was associated with 3-month poor outcome after aSAH when we controlled for Fisher score, acute hydrocephalus, delayed cerebral ischemia, symptomatic cerebral vasospasm, serum glucose and phosphate levels, and glucose-potassium ratio. Receiver operating characteristic analysis showed that the area under the curve for glucose-phosphate ratio was significantly higher than age and intraventricular hemorrhage.

CONCLUSIONS

The study shows that the glucose-phosphate ratio is a potential biomarker that can reflect disease severity and prognosis in aSAH patients.

Reduced Serum Phosphorus Levels Were Associated with Metabolic Syndrome in Men But Not in Women: A Cross-Sectional Study among the Japanese Population

BACKGROUND

Reduced serum phosphorus (SP) levels are reported to be associated with insulin resistance and metabolic syndrome (MetS). However, there have been a few gender-specific studies although SP levels are substantially different between men and women.

METHODS

This is a cross-sectional study. A total of 16,041 subjects (9,076 men and 6,965 women) were analyzed. The subjects were divided into 3 groups of gender-specific tertiles based on phosphorus levels: the lowest (T1), middle (T2), and the highest (T3).

RESULTS

SP levels were significantly lower in subjects with MetS than in those without MetS in men but not in women. Waist circumference and fasting plasma glucose were negatively and high-density lipoprotein cholesterol was positively correlated with SP levels both in men and women. Blood pressure (BP) and triglycerides (TG) were negatively correlated with SP levels in men, while they were positively correlated with SP levels in women. Lower SP levels were associated with the prevalence of MetS in men (T1; 19.9%, T2; 16.9%, and T3; 14.3%; p < 0.001) but not in women (T1; 14.1%, T2; 16.6%, and T3; 15.3%; p = 0.282).

CONCLUSION

BP and TG were unexpectedly positively correlated with SP levels in women. Reduced SP levels were associated with MetS in men but not in women.

Serum phosphate is related to adiposity in healthy adults

BACKGROUND

Inorganic phosphate is a crucial component of cellular energy metabolism. We have identified an inverse relationship between serum phosphate concentration and fat mass in a cohort of healthy men. This study reports those data and determines whether this association is present in two female populations.

METHODS

Cross-sectional data from three independent cohorts, consisting of healthy adult males (Male Cohort, n = 323) and healthy postmenopausal women (Female Cohort 1, n = 185; and Female Cohort 2, n = 1471), are reported. Associations between serum phosphate and weight, body mass index (BMI), fat mass and bone mineral density (BMD) were assessed. In a fourth cohort of postmenopausal women (FGF23 Cohort, n = 20), associations between fibroblast growth factor 23 (FGF23), weight and BMI were assessed.

RESULTS

Serum phosphate correlated inversely with weight, BMI and fat mass across all three cohorts (r = -0·13 to -0·31, P < 0·0001-0·02). Associations were diminished after adjustment for PTH, but remained significant. In the FGF23 Cohort, FGF23 was positively correlated with weight (r = 0·60, P = 0·007) and BMI (r = 0·49, P = 0·03). Phosphate was inversely associated with BMD in Female Cohorts 1 and 2 (r = -0·08 to -0·29, P < 0·0001-0·02). This relationship was attenuated, but remained significant at most sites, following adjustment for age, fat mass, renal function and 25-hydroxyvitamin D.

CONCLUSIONS

Serum phosphate is inversely associated with measures of adiposity in both women and men, largely independently of PTH. FGF23 might mediate these associations. This relationship may be an unrecognized confounder in some of the correlates of serum phosphate already described.

Phosphorus Supplementation Recovers the Blunted Diet-Induced Thermogenesis of Overweight and Obese Adults: A Pilot Study

Diet-induced thermogenesis (DIT) is believed to be largely related to ATP production, which is dependent on phosphorus (P) availability. We aimed to test the effect of P addition on DIT of lean and overweight/obese healthy subjects. DIT was measured with or without P in 10 lean and 13 overweight/obese adults in a double-blind randomized cross-over pilot study with one week washout period. After 10 h overnight fast, resting metabolic rate, respiratory quotient, and substrate utilization were measured at fasting and every 30 min for 3 h after subjects drank a standardized glucose solution, with P (500 mg) or placebo pills. Subjective ratings of hunger and satiety were assessed before and after the end of each experiment using validated visual analogue scale (VAS) questionnaires. Overweight/obese subjects had a blunted DIT with placebo, while P supplementation induced a 23% increase in their DIT area under the curve (p < 0.05), which was associated with a significant increase in carbohydrate oxidation. Subjects had lower appetite following P supplementation, which was expressed as a significantly (p = 0.02) lower desire to eat a meal (4.0 ± 0.7 cm) compared with placebo (5.8 ± 0.9 cm). P supplementation recovers the blunted diet-induced thermogenesis in overweight and obese subjects and enhances their postprandial satiety.

Calcium and Vitamin D Supplement Prescribing Practices among Providers Caring for Children with Autism Spectrum Disorders: Are We Addressing Bone Health?

Children with autism spectrum disorders (ASD) have several risk factors for low bone mineral density. The gluten-free, casein-free (GFCF) diet is a complementary therapy sometimes used in ASD that raises concerns for the adequacy of calcium and vitamin D intake. This study evaluated the prescribing practices of calcium and vitamin D supplements and the practice of checking 25-hydroxy vitamin D (25(OH)D) levels by providers in 100 children with ASD, 50 of whom were on the GFCF diet. Fifty-two percent and 46% of children on the GFCF diet were on some form of vitamin D and calcium supplements, respectively, compared to 18% and 14% of those not on this diet. Twenty-four percent of children in the GFCF group had a documented 25(OH)D level compared to none in the non-GFCF group. The data highlight a gap in calcium and vitamin D supplement prescribing practices among providers caring for children with ASD as well as a gap in the practice of checking 25(OH)D levels.

Parathyroidectomy Decreases Insulin Resistance Index in Patients with Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) has been considered a cause of insulin resistance (IR) and impaired glucose metabolism. However, there are conflicting results related with the recovery of insulin resistance in patients with PHPT following curative parathyroidectomy. Our aim is to evaluate the effects of curative parathyroidectomy on IR in patients with PHPT. This is a prospective interventional study. Twenty-one consecutive patients with symptomatic PHPT were included into the study. All patients underwent parathyroidectomy. Fasting serum glucose, calcium, phosphorous, parathormone, plasma insulin, and vitamin D levels were measured both at baseline and 2 months after parathyroidectomy. Insulin resistance was calculated by homeostasis of model assessment-insulin resistance (HOMA-IR). Two months after curative parathyroidectomy, serum levels of calcium (p = 0.001), PTH (p < 0.001), insulin (p = 0.003), and HOMA-IR (p = 0.003) decreased, while phosphorous levels increased (p = 0.001). During this period, no changes were observed at vitamin D and glucose levels. We concluded that curative parathyroidectomy decreases HOMA-IR index in patients with PHPT. Studies with larger population and longer follow-up period are required to confirm our results.

Phosphorus ingestion improves oral glucose tolerance of healthy male subjects: a crossover experiment

Background

Fasting serum phosphorus (P) was reported to be inversely related to serum glucose and insulin, while the impact of P ingestion is not well documented. The effect of P intake with or before glucose ingestion on postprandial glucose and insulin statuses was investigated.

Method

Two cross over experiments using healthy male subjects were conducted. Experiment 1: Overnight fasted subjects (n = 7) randomly received: 500 mg of P tablets, glucose (75 g) solution with placebo or 500 mg of P tablets. Experiment 2: Overnight fasted subjects (n = 8) underwent similar procedures to those of experiment 1, except that placebo or 500 mg P tablets were given 60 min prior to glucose ingestion.

Results

In both experiments, serum P decreased following glucose ingestion. Co-ingestion of P with glucose improved, at time 60 min, postprandial glucose (P < 0.05), insulin (P < 0.05), and insulin sensitivity index (p < 0.006), while P pre-ingestion failed to exert similar effect.

Conclusion

This study suggests that postprandial glucose and insulin are affected by exogenous P supply, especially when co-ingested with glucose.

Effect of intermittent PTH treatment on plasma glucose in osteoporosis: A randomized trial

We investigated the effect of bone turnover on glucose homeostasis, fat distribution and adipokine production during anabolic treatment with PTH. This is a parallel, randomized controlled, open label, trial. The randomization was done by computer generated tables to allocate treatments. Forty-six postmenopausal osteoporotic non-diabetic women were assigned to treatment with calcium and colecalcipherol with (24) or without (22) PTH 1-84. Patients were recalled after 3, 6, 12 and 18 months of treatment and markers of bone turnover, glucose metabolism, adipokine secretion and fat distribution were analyzed. Markers of bone turnover and adipokines were measured by ELISA. Glucose metabolism was evaluated by an oral glucose load test and insulin resistance and secretion were calculated. Fat and lean mass were evaluated by anthropometric measures. The effect of treatment on measured variables was analyzed by repeated measure test, and its effect on glucose was also evaluated by mediation analysis after correction for possible confounders. Twenty patients in the calcium and vitamin D groups and 19 in the group treated with PTH 1-84 completed the study. There were no significance adverse events. Treatment with PTH increases osteocalcin, both total (OC) and undercarboxylated (uOC), and decreases blood glucose, without influence on insulin secretion, resistance and pancreatic β cell function. Treatment with PTH does not influence fat distribution and adipokine production. The results of the mediation analyses suggest a total effect of PTH on blood glucose, moderately mediated by OC and to a less extent by uOC. Here we suggest that treatment with PTH influences glucose metabolism partially through its effect on bone turnover, without influence on insulin secretion, resistance, pancreatic β cell function and fat mass.

Increased inflammation and decreased insulin sensitivity indicate metabolic disturbances in zoo-managed compared to free-ranging black rhinoceros (Diceros bicornis)

Black rhinoceros (rhinos) living in zoos express a host of unusual disease syndromes that are associated with increased morbidity and mortality, including hemolytic anemia, rhabdomyolysis, hepatopathy and ulcerative skin disease, hypophosphatemia and iron overload. We hypothesized that iron overload is a consequence and indicator of disturbances related to inflammation and insulin/glucose metabolism. The objectives of this study were to: (1) generate the first baseline information on biomarkers of inflammation (tumor necrosis factor alpha [TNFα], serum amyloid A [SAA]), insulin sensitivity (insulin, glucose and proxy calculations of insulin sensitivity), phosphate and iron stores (ferritin) using banked serum from free-ranging black rhinos; and (2) then compare serum biomarkers between zoo-managed (n=86 individuals) and free-ranging (n=120) animals. Enzyme immunoassays were validated for serum and then biomarker levels analyzed using mixed models while controlling for sex, age and year of sample collection. Concentrations of TNFα, SAA, insulin and insulin-to glucose ratio were higher (P<0.05) in black rhinos managed in ex situ conditions compared to free-living counterparts. Findings indicate that the captive environment is contributing to increased inflammation and decreased insulin sensitivity in this endangered species.

Calcium and phosphate concentrations and future development of type 2 diabetes: the Insulin Resistance Atherosclerosis Study

AIMS/HYPOTHESIS

Low phosphate and high calcium concentrations have been linked to altered glucose tolerance and reduced insulin sensitivity in non-diabetic individuals. The aim of this study was to examine the relationships of calcium and phosphate levels and the calcium-phosphate product with the development of type 2 diabetes.

METHODS

Participants were 863 African-Americans, Hispanics and non-Hispanic whites in the Insulin Resistance Atherosclerosis Study who were free of diabetes at baseline. The mean follow-up period was 5.2 years. The insulin sensitivity index (SI) and acute insulin response (AIR) were directly measured using the frequently sampled IVGTT.

RESULTS

Calcium concentration (OR per 1 SD unit increase, 1.26 [95% CI 1.04, 1.53]) and calcium-phosphate product (OR 1.29 [95% CI 1.04, 1.59]) were associated with incident diabetes after adjustment for demographic variables, family history of diabetes, and 2 h glucose. The relationship between phosphate concentration and progression to diabetes was close to statistical significance (OR 1.21 [95% CI 0.98, 1.49]). Calcium concentration (OR 1.37 [95% CI 1.09, 1.72]) and calcium-phosphate product (OR 1.39 [95% CI 1.09, 1.77]) remained associated with incident diabetes after additional adjustment for BMI, plasma glucose, SI, AIR, C-reactive protein, estimated GFR, diuretic drugs and total calcium intake.

CONCLUSIONS/INTERPRETATION

Elevated serum calcium and calcium-phosphate product are associated with increased risk of developing type 2 diabetes independently of measured glucose, insulin secretion and insulin resistance. Future studies need to analyse the role of calcium-phosphate homeostasis in the pathophysiology of diabetes.

Refeeding and metabolic syndromes: two sides of the same coin

Refeeding syndrome describes the metabolic and clinical changes attributed to aggressive rehabilitation of malnourished subjects. The metabolic changes of refeeding are related to hypophosphatemia, hypokalemia, hypomagnesemia, sodium retention and hyperglycemia, and these are believed to be mainly the result of increased insulin secretion following high carbohydrate intake. In the past few decades, increased consumption of processed food (refined cereals, oils, sugar and sweeteners, and so on) lowered the intake of several macrominerals (mainly phosphorus, potassium and magnesium). This seems to have compromised the postprandial status of these macrominerals, in a manner that mimics low grade refeeding syndrome status. At the pathophysiological level, this condition favored the development of the different components of the metabolic syndrome. Thus, it is reasonable to postulate that metabolic syndrome is the result of long term exposure to a mild refeeding syndrome.

PHEX mimetic (SPR4-peptide) corrects and improves HYP and wild type mice energy-metabolism

CONTEXT

PHEX or DMP1 mutations cause hypophosphatemic-rickets and altered energy metabolism. PHEX binds to DMP1-ASARM-motif to form a complex with α5β3 integrin that suppresses FGF23 expression. ASARM-peptides increase FGF23 by disrupting the PHEX-DMP1-Integrin complex. We used a 4.2 kDa peptide (SPR4) that binds to ASARM-peptide/motif to study the DMP1-PHEX interaction and to assess SPR4 for the treatment of energy metabolism defects in HYP and potentially other bone-mineral disorders.

DESIGN

Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle (VE) into wild-type mice (WT) and HYP-mice (PHEX mutation) for 4 weeks.

RESULTS

SPR4 partially corrected HYP mice hypophosphatemia and increased serum 1.25(OH)2D3. Serum FGF23 remained high and PTH was unaffected. WT-SPR4 mice developed hypophosphatemia and hypercalcemia with increased PTH, FGF23 and 1.25(OH)2D3. SPR4 increased GAPDH HYP-bone expression 60× and corrected HYP-mice hyperglycemia and hypoinsulinemia. HYP-VE serum uric-acid (UA) levels were reduced and SPR4 infusion suppressed UA levels in WT-mice but not HYP-mice. SPR4 altered leptin, adiponectin, and sympathetic-tone and increased the fat mass/weight ratio for HYP and WT mice. Expression of perlipin-2 a gene involved in obesity was reduced in HYP-VE and WT-SPR4 mice but increased in HYP-SPR4 mice. Also, increased expression of two genes that inhibit insulin-signaling, ENPP1 and ESP, occurred with HYP-VE mice. In contrast, SPR4 reduced expression of both ENPP1 and ESP in WT mice and suppressed ENPP1 in HYP mice. Increased expression of FAM20C and sclerostin occurred with HYP-VE mice. SPR4 suppressed expression of FAM20C and sclerostin in HYP and WT mice.

CONCLUSIONS

ASARM peptides and motifs are physiological substrates for PHEX and modulate osteocyte PHEX-DMP1-α5β3-integrin interactions and thereby FGF23 expression. These interactions also provide a nexus that regulates bone and energy metabolism. SPR4 suppression of sclerostin and/or sequestration of ASARM-peptides improves energy metabolism and may have utility for treating familial rickets, osteoporosis, obesity and diabetes.

High serum phosphate and triglyceride levels in smoking women and men with CVD risk and type 2 diabetes

BACKGROUND

Both low and high serum phosphate levels may be associated with morbidity and mortality from cardiovascular disease. As smoking increases risk for type 2 diabetes (as shown by dyslipidemia and hyperglycemia), we wanted to study whether smoking and type 2 diabetes were associated with serum phosphate and triglyceride levels independently from other CVD risk factors.

METHODS

Upon admittance to the Vindeln Health Education Centre (VHE-centre) for a four-week comprehensive lifestyle intervention, the participants (1408 women and 1096 men) completed a questionnaire that included their smoking habits - current smoker or non-smoker. We used multiple linear regression analyses to investigate the association between smoking and other CVD risk factors with S-P and S-TG levels.

RESULTS

In the non-type 2 diabetes populations, the smokers, compared to the non-smokers, had higher S-P and higher serum triglycerides (S-TG). In women, serum-TG in smokers with type 2 diabetes was higher than in smokers with non-type 2 diabetes. Non-type 2 diabetes patients exhibited an inverse relation between S-Glucose (S-Glu) and S-P and a positive association with S-TG. For men only, an association was seen between age (-) and S-Crea (-) and S-P. For women only, an association was seen between BMI (-) and S-Cholesterol (+) (S-Chol) and S-P.

CONCLUSIONS

Compared to non-smokers, smoking women with non-type 2 diabetes and smoking men with type 2 diabetes had a higher level of S-P and S-TG. The association between smoking and S-P and S-TG levels still existed after adjusting for age and CVD risk factors in the multiple linear regression analyses.

TRIAL REGISTRATION

The study has been registered as a sub-study to the Lifestyle Intervention Trial no. ISRCTN79355192.

Low phosphorus status might contribute to the onset of obesity

Overweight and obesity are becoming global health problems. Although genetics certainly plays a role, weight gain is ultimately the result of a failure in the balance between energy expenditure and energy intake. Obesity during the past few decades was paralleled with several changes in dietary habits favouring low phosphorus consumption. This is believed to compromise adenosine triphosphate (ATP) production that is involved in the regulation of energy metabolism. Ingestion of high-carbohydrate-low phosphorus food is known to increase insulin release, to simultaneously stimulate peripheral uptake of phosphorus and the phosphorylation of many compounds. This creates a competition for phosphorus that compromises its availability for ATP production, possibly translated into low diet-induced thermogenesis. Moreover, reduced hepatic ATP production is believed to be transmitted through neural afferents to the central nervous system, resulting in an increase in food intake. On the other hand, the positive relation between phosphorus and red blood cell 2,3-diphosphoglycerate, which reduces oxygen affinity to haemoglobin, would be expected to reduce the capacity for physical activity. In line with that, plasma phosphorus status was reported to be inversely related to body weight. Adequate intakes of phosphorus are thus potentially protective against rising obesity epidemic across the globe.

Bone Remodeling and Energy Metabolism: New Perspectives

Bone mineral, adipose tissue and energy metabolism are interconnected by a complex and multilevel series of networks. Calcium and phosphorus are utilized for insulin secretion and synthesis of high energy compounds. Adipose tissue store lipids and cholecalciferol, which, in turn, can influence calcium balance and energy expenditure. Hormones long-thought to solely modulate energy and mineral homeostasis may influence adipocytic function. Osteoblasts are a target of insulin action in bone. Moreover, endocrine mediators, such as osteocalcin, are synthesized in the skeleton but regulate carbohydrate disposal and insulin secretion. Finally, osteoblasts and adipocytes originate from the same mesenchymal progenitor. The mutual crosstalk between osteoblasts and adipocytes within the bone marrow microenvironment plays a crucial role in bone remodeling. In the present review we provide an overview of the reciprocal control between bone and energy metabolism and its clinical implications.