Serum phosphate, blood pressure, and the metabolic syndrome--20-year follow-up of middle-aged men

Impact of serum phosphate on severity and functional outcomes after ischemic stroke in young adults

BACKGROUND AND AIMS

Serum phosphate is an essential nutrient that plays multiple physiological roles in cardiovascular function. The aim of this study was to investigate the association between serum phosphate and stroke severity and prognosis in ischemic stroke and transient ischemic attack (TIA) among young adults.

METHODS AND RESULTS

We retrospectively recruited patients with acute ischemic stroke and TIA aged 18-45 years. The primary outcome was 90-day poor functional outcome (modified Rankin Scale score of 2-6). The secondary outcomes included stroke severity (NIHSS ≥5 was defined as moderate to severe stroke) and poor functional outcome at hospital discharge. A total of 687 patients with a mean age of 36.8 years were enrolled. Lower serum phosphate levels were significantly associated with more severe stoke (P for trend = 0.017). Compared with the fourth quartile, the odds ratio (95% CI) of the first quartile was 1.85 (1.19-3.22) for moderate to severe stroke. After adjusting for confounders other than stroke severity, the odds ratio (95% CI) of the first quartile was 1.74 (1.06-2.86) for poor functional outcome at hospital discharge and 1.90 (1.09-3.31) at 90-day follow-up compared with the fourth quartile. However, the significant association between serum phosphate and poor functional outcomes disappeared after stroke severity was further adjusted.

CONCLUSIONS

Serum phosphate is more likely a marker of stroke severity than a contributor to poor functional outcomes after ischemic stroke and TIA in young adults. Lower serum phosphate levels were associated with more severe stroke.

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.

Association of urine phthalate metabolites, bisphenol A levels and serum electrolytes with 24-h blood pressure profile in adolescents

Background

Among the possible causes of hypertension in adolescence, electrolyte imbalances and environmental pollutants are drawing increasing attention. We aimed to examine the relationship between bisphenol A (BPA), phthalate metabolites, and serum electrolytes and blood pressure.

Methods

Eighty-six participants aged 12–15 years were included in the study. Body mass index (BMI), office blood pressure and 24-h ambulatory blood pressure measurements (ABPM), and carotid intima-media thickness were determined. Blood samples were taken for hemogram, renal function tests, and serum electrolytes. Free- and total-BPA and phthalate metabolites were analyzed from urine samples.

Results

Of the participants, 34 were evaluated as normal blood pressure profile, 33 as white-coat hypertension (WCHT), and 19 as ABPM-hypertension. Adolescents in ABPM- hypertension groups had higher BMI-standard deviation score (SDS), leucocyte, platelet count; but lower serum chloride, compared to the normal blood pressure profile group. The percentage of adolescents with detectable urinary mono-benzyl phthalate (MBzP) was higher in ABPM-hypertension (42.1%) and WCHT groups (33.3%), compared to the normal blood pressure profile group (5.9%, p = 0.004). Associations between MBzP and ABPM- hypertension and WCHT were remained after confounding factor adjustment. Adolescents with detectable MBzP levels had also higher “albumin-corrected calcium” and lower serum phosphate and “albumin-corrected calcium x phosphate product” compared to others. Adolescents with detectable urinary MBzP levels had higher blood pressure profiles in some 24-h (mean arterial pressure-SDS, systolic blood pressure-SDS), daytime (systolic blood pressure-SDS), and night-time (mean arterial pressure-SDS, systolic blood pressure-SDS, and diastolic blood pressure-SDS) measurements, compared to others. WCHT was found to be associated negatively with monomethyl phthalate and the sum of dibutyl phthalate metabolites and ABPM-HT with MCPP. There was no significant association between blood pressure profiles and free- and total-BPA status.

Conclusion

MBzP was associated with adverse blood pressure profiles in adolescence. Additive follow-up studies are necessary for cause-effect relations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02774-y.

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.

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.

Is fibroblast growth factor 23 a new cardiovascular risk marker in gestational diabetes?

OBJECTIVE

This study was designed to compare the serum levels of fibroblast growth factor 23 (FGF23) among patients with gestational diabetes mellitus (GDM) and healthy pregnant women, and to evaluate the association between hormonal and metabolic parameters.

SUBJECTS AND METHODS

A total of 82 pregnant women were consecutively enrolled in the study. Of these, 46 were diagnosed as having GDM; the remaining 36 healthy pregnant women served as controls in a cross-sectional study design. The womens' ages ranged from 22 to 38 years and gestational ages, from 24 to 28 weeks. Serum samples were analyzed for FGF23 levels using an enzyme-linked immunosorbent assay.

RESULTS

Serum FGF23 levels were increased in patients with GDM compared with controls (median, 65.3 for patients with GDM vs. 36.6 ng/mL for healthy controls; p = 0.019). Mean fasting glucose (105.6 ± 7.4 vs. 70.2 ± 7.2 mg/dL, p < 0.001), HbA1c (5.6 ± 0.5 vs. 4.9 ± 0.5%, p < 0.001), insulin (median, 11.1 vs. 8.7 µIU/mL, p = 0.006) and HOMA-IR (3.0 (1.8) vs 1.4 (0.6), p < 0.001) levels were significantly higher in patients with GDM than in controls. Serum FGF23 level was positively correlated with body mass index (r2 = 0.346, p < 0.05), FPG (r2 = 0.264, p < 0.05), insulin (r2 = 0.388, p < 0.05), HOMA-IR (r2 = 0.384, p < 0.05).

CONCLUSION

Serum FGF23 levels were higher in women with GDM compared with controls. The present findings suggest that FGF23 could be a useful marker of cardiovascular disease in GDM.

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.

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.

Parathyroid hormone is a plausible mediator for the metabolic syndrome in the morbidly obese: a cross-sectional study

BACKGROUND

The biological mechanisms in the association between the metabolic syndrome (MS) and various biomarkers, such as 25-hydroxyvitamin D (vit D) and magnesium, are not fully understood. Several of the proposed predictors of MS are also possible predictors of parathyroid hormone (PTH). We aimed to explore whether PTH is a possible mediator between MS and various possible explanatory variables in morbidly obese patients.

METHODS

Fasting serum levels of PTH, vit D and magnesium were assessed in a cross-sectional study of 1,017 consecutive morbidly obese patients (68% women). Dependencies between MS and a total of seven possible explanatory variables as suggested in the literature, including PTH, vit D and magnesium, were specified in a path diagram, including both direct and indirect effects. Possible gender differences were also included. Effects were estimated using Bayesian path analysis, a multivariable regression technique, and expressed using standardized regression coefficients.

RESULTS

Sixty-eight percent of the patients had MS. In addition to type 2 diabetes and age, both PTH and serum phosphate had significant direct effects on MS; 0.36 (95% Credibility Interval (CrI) [0.15, 0.57]) and 0.28 (95% CrI [0.10,0.47]), respectively. However, due to significant gender differences, an increase in either PTH or phosphate corresponded to an increased OR for MS in women only. All proposed predictors of MS had significant direct effects on PTH, with vit D and phosphate the strongest; -0.27 (95% CrI [-0.33,-0.21]) and -0.26 (95% CrI [-0.32,-0.20]), respectively. Though neither vit D nor magnesium had significant direct effects on MS, for women they both affected MS indirectly, due to the strong direct effect of PTH on MS. For phosphate, the indirect effect on MS, mediated through serum calcium and PTH, had opposite sign than the direct effect, resulting in the total effect on MS being somewhat attenuated compared to the direct effect only.

CONCLUSION

Our results indicate that for women PTH is a plausible mediator in the association between MS and a range of explanatory variables, including vit D, magnesium and phosphate.

Serum phosphate in white-coat hypertensive patients: focus on dipping status and metabolic syndrome

Recent studies indicate an association between serum phosphate levels and blood pressure in hypertensive patients. A growing body of evidence suggests that white-coat hypertension (WCH) is associated with target organ damage. Furthermore, metabolic syndrome (MS) and a non-dipping pattern are associated with increased cardiovascular risk. The purpose of this study was to explore the nocturnal blood pressure fall in patients with WCH according to their serum phosphate levels and number of MS components fulfilled. The study included 2600 patients with WCH who attended our outpatient clinics. All patients underwent repeated office blood pressure measurements, 24-h ambulatory blood pressure monitoring and full clinical and laboratory evaluation. The diagnosis of MS was made according to the Adult Treatment Panel III criteria. Dipping pattern was defined as follows: 'dippers' had a nocturnal systolic blood pressure (NSBP) fall > or =10% but <20%; 'non-dippers' had an NSBP fall <10%; 'extreme dippers' had an NSBP fall > or =20% and 'reverse dippers' had an NSBP increase. There were 314 extreme dippers, 1337 dippers, 734 non-dippers and 116 reverse dippers. Reverse dippers presented with significantly lower levels of serum phosphate, whereas extreme dippers had significantly higher levels (3.39+/-3.29 vs. 3.58+/-3.52 mg per 100 ml, P<0.0001). The patients were classified according to the number of MS components and the main observation was the inverse relationship of serum phosphate with MS components (3.53+/-0.36, 3.50+/-0.38, 3.49+/-0.38, 3.44+/-0.36 and 3.35+/-0.31 mg per 100 ml, respectively, P=0.003). Patients with WCH and low serum phosphate levels appear to have a higher incidence of a non-dipping NSBP profile and an impaired metabolic profile. This observation may be important for the stratification of the cardiovascular risk in WCH patients.