The fructose tolerance test in patients with chronic kidney disease and metabolic syndrome in comparison to healthy controls.

BACKGROUND: Fructose acutely raises serum uric acid in normal subjects, but the effect in subjects with metabolic syndrome or subjects with chronic kidney disease is unknown. The aim of the study was to evaluate changes in serum uric acid during the fructose tolerance test in patients with chronic kidney disease, metabolic syndrome with comparison to healthy controls. METHODS: Studies were performed in 36 subjects with obesity (body mass index >30) and metabolic syndrome, 14 patients with stage 3 chronic kidney disease, and 25 healthy volunteers. The fructose tolerance test was performed in each patient. The change in serum uric acid during the fructose challenge was correlated with baseline ambulatory blood pressure, serum uric acid, metabolic, and inflammatory markers, and target organ injury including carotid intima media thickness and renal resistive index (determined by Doppler). RESULTS: Absolute serum uric acid values were highest in the chronic kidney disease group, followed by the metabolic syndrome and then healthy controls. Similar increases in serum uric acid in response to the fructose tolerance test was observed in all three groups, but the greatest percent rise was observed in healthy controls compared to the other two groups. No significant association was shown between the relative rise in uric acid and clinical or inflammatory parameters associated with kidney disease (albuminuria, eGFR) or metabolic syndrome. CONCLUSIONS: Subjects with chronic kidney disease and metabolic syndrome have higher absolute uric acid values following a fructose tolerance test, but show a relatively smaller percent increase in serum uric acid. Changes in serum uric acid during the fructose tolerance test did not correlate with changes in metabolic parameters, inflammatory mediators or with target organ injury. These studies suggest that acute changes in serum uric acid in response to fructose do not predict the metabolic phenotype or presence of inflammatory mediators in subjects with obesity, metabolic syndrome or chronic kidney disease. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov. Identifier : NCT01332526. www.register.clinicaltrials.gov/01332526.

25-hydroxyvitamin D, biomarkers of endothelial dysfunction and subclinical organ damage in adults with hypertension.

BACKGROUND: The mechanism that underlies the association between low 25-hydroxyvitamin D [25(OH)D] and hypertension is not well understood; it seems to involve regulation of the renin-angiotensin-aldosterone system and the impact on endothelial function, cardiac remodeling, and subclinical organ damage. Vitamin D supplementation presents an ambiguous effect on endothelial function and arterial stiffness. We assess serum 25(OH)D3, biomarkers of endothelial dysfunction (soluble intercellular adhesion molecule [sICAM], C-reactive protein [CRP], homocysteine [Hcy]) and subclinical organ damage in adults with newly diagnosed untreated hypertension. METHODS: Patients were classified based on ambulatory blood pressure monitoring: 98 had hypertension, whereas in 60 persons BP was normal. Laboratory assays including serum 25(OH)D3, hsCRP, Hcy, sICAM, glucose, insulin, lipids, echocardiography, pulse wave velocity (PWV), intima-media thickness (IMT), and left-ventricular mass (LVM) measurements were performed. RESULTS: 25(OH)D3 was significantly lower in hypertensive patients. The logistic regression analysis indicated that 25(OH)D3 reduced the probability of hypertension occurrence after adjusting for body mass index (BMI). 25(OH)D3 in those with hypertension correlated significantly with systolic BP (SBP; r = -0.39), PWV, IMT (r = -0.33), and diastolic BP (r = -0.26). Multiple regression analysis in patients with hypertension revealed that 25(OH)D3 and sICAM accounted for up to 27% of SBP variation after adjusting for age, BMI, and smoking. 25(OH)D3 and either PWV or IMT accounted for 23% of SBP variation. The impact of 25(OH)D3 was 10%. CONCLUSION: The impact of 25(OH)D3 on SBP variation, mediated by its effect on endothelial dysfunction and subclinical organ damage, is modest but significant.

The impact of fructose on renal function and blood pressure.

Fructose is a sugar present in sucrose, high-fructose corn syrup, honey, and fruits. Fructose intake has increased markedly in the last two centuries, primarily due to increased intake of added sugars. Increasing evidence suggests that the excessive intake of fructose may induce fatty liver, insulin resistance, dyslipidemia, hypertension, and kidney disease. These studies suggest that excessive intake of fructose might have an etiologic role in the epidemic of obesity, diabetes, and cardiorenal disease.

The influence of intravenous 1,25(OH)2D3 therapy on glucose metabolism in hemodialyzed patients with secondary hyperparathyroidism.

Glucose intolerance, insulin resistance and hyperinsulinemia are common findings in end-stage renal disease patients. Parathormone (PTH) and vitamin D3 are linked with disturbances of glucose metabolism. Glycated hemoglobin (HbA1c) reflects long-term glycemic control. HbA1c is a marker of increased risk of death in diabetic patients but also in general population. The aim of the study was to investigate the influence of 1,25(OH)2D3 therapy on long-term control of glycemia in hemodialyzed (HD) patients with severe secondary hyperparathyroidism (SHP). Eight HD patients with SHP (PTH=1088.6+/-472.2) were given intravenous 1,25(OH)2D3 1-2 microg thrice a week, for 12 weeks (mean dose 4.5 microg/week). At baseline and after 12 weeks fasting blood was sampled for: glucose, insulin, HbA1c, PTH. Insulin/glucose ratio (I/G) was calculated as marker of insulin resistance. Results were compared with 14 healthy volunteers (controls) matched for age, sex and BMI. At baseline I/G was higher in HD vs controls 0.110+/-0.045 vs 0.073+/-0.021 (p = 0.02), and of borderline significance at follow-up (0.106+/-0.053, p=0.05 vs controls). PTH decreased significantly to 506.1+/-646.3 (p<0.02) during therapy. Significant decrease of HbA1c in HD patients was observed (5.84+/-0.40 vs 5.13+/-0.51; p=0.01), while fasting glucose, insulin and I/G did not change significantly. Intravenous 1,25(OH)2D3 therapy is successful, even in patients with severe secondary hyperparathyroidism. Significant decrease in HbA1c with stable insulin concentration may indicate positive impact of intravenous 1,25(OH)2D3 therapy on long-term glucose metabolism.

[Seasonal profile of calcium-phosphate metabolism in hemodialysis patients with secondary hyperparathyroidism]. / Roczny profil gospodarki wapniowo-fosforanowej u chorych hemodializowanych z wtórna nadczynnoscia przytarczyc.

Sunlight UV plays an important role in synthesis of active vitamin D3. Vitamin D3 concentration depends on seasonal sunlight exposure. It was not state, whether these changes may act on secondary hyperparathyroidism (SHP) in hemodialysis (HD) patients. The aim of our analysis was to assess the relationship between seasons and parameters of Ca-P metabolism in HD patients with SHP. We studied 30 pts (F = 17, M = 13), aged 20-72 years (mean 49 +/- 13), duration of HD therapy 3-132 months (mean 54.4 +/- 43.7), treated with alphacalcidol (1 alpha OHD3) due to SHP. Blood was collected for PTH, Ca, P concentrations in January (1), April (IV), July (VII) and October (X); also doses of CaCO3 and 1 alpha OHD3 were analyzed. The day duration was: 7 hours and 51 minutes (I), 12.53 (IV), 16.37 (VII) and 11.39 (X), respectively. PTH concentration was significantly higher in I vs IV (882 +/- 588 vs 691 +/- 511 pg/ml, p < 0.05) and higher in X vs VII (831 +/- 600 vs 701 +/- 525 pg/ml, p < 0.05), despite drug dosage did not differ. Calcium concentration was lower in I vs IV and X, and phosphate concentration was lower in I compared to IV, VII i X. These changes suggest presence of seasonal rhythm of PTH concentration in HD patients with SHP. When assessing the effectiveness of SHP therapy, the season of the year when PTH concentration was tested should be taken into account.