高通量血液透析治疗对尿毒症患者心功能、微炎症因子及血清磷、全段甲状旁腺激素清除的影响

目的:分析高通量血液透析治疗尿毒症的临床价值.方法:将2016年9月至2018年9月我院收治的263例尿毒症患者按治疗方式不同分为对照组(低通量血液透析,n=121)和观察组(高通量血液透析,n=142),比较两组患者治疗前与治疗3个月后心功能[左室舒张期末内径(Left ventricular end diastol...     

Effects of propranolol and verapamil on plasma ionized calcium and parathyroid hormone in short-term intense isokinetic leg exercise

Physical exercise, beta-adrenergic stimulation and calcium channel blockade can affect calcium homeostasis. The present study investigated, in eight healthy males, the effects of orally administered propranolol or verapamil during a 2-min maximal, isokinetic, leg exercise. Immediately after exercise the plasma ionized calcium concentrations were increased, in control and drug tests, by 5-6%, and within 5 min of recovery they were almost returned to baseline. Serum parathyroid hormone (PTH) concentrations were unchanged at termination of exercise, but they increased during the first 5 min of recovery, coincident with the decline in calcium concentrations, which, however, were still elevated. Neither verapamil nor propranolol selectively changed basal or exercise plasma ionized calcium or serum PTH concentrations. Muscle strength, blood pH, lactate concentrations and plasma volume changes were not affected by any drug. Verapamil did not have any specific effect on the concentrations of plasma magnesium, phosphate, potassium or sodium while propranolol increased the concentrations of plasma potassium and decreased those of phosphate during exercise as well as recovery.     

Effects of secretin on parathyroid hormone and calcium in normal subjects, patients with hyperparathyroidism and patients with gastrinoma

In vitro studies have demonstrated that secretin can stimulate the release of parathyroid hormone (PTH), but reports concerning its effects on PTH and calcium in vivo are contradictory. To examine this question further, a bolus injection of secretin (75 IU) was given to 12 normal subjects and 10 patients with primary hyperparathyroidism (HPT). Six of the patients had multiple endocrine neoplasia and five had endocrine pancreatic tumours (EPT). Three normocalcaemic patients with EPT were also included in the study. The mean serum gastrin level rose significantly (from 19 to 40 pmol/l, p less than 0.01) within 15 min of secretin injection in the normal subjects. HPT patients without EPT had a somewhat higher mean basal level of gastrin (39 pmol/l, p less than 0.05 compared with controls), but it did not increase significantly after the secretin bolus. In six EPT patients the gastrin concentrations rose by more than 300 pmol/l. Although secretin had a biological capacity to release gastrin, it had no discernible effects on either serum PTH or serum calcium in any of the groups studied. Nor were any changes in PTH or calcium observed when secretin was given as a continuous infusion (3 IU/kg/h) over 90 min. Thus, our data do not support the concept that secretin, in vivo, is a secretagogue of PTH.     

Effects of parathyroid hormone on renal tubular calcium and phosphate handling

Central to the maintenance of calcium homeostasis is the regulated reabsorption of calcium along the nephron. To this end, parathyroid hormone (PTH) is released from the parathyroid gland in response to lowered plasma calcium levels. This hormone acts through the PTH 1 receptor along the nephron to increase urinary phosphate excretion and decrease urinary calcium excretion. In the proximal tubule, PTH inhibits phosphate reabsorption by reducing the abundance of sodium phosphate cotransporters in the apical membrane. PTH likely decreases calcium reabsorption from the proximal tubule, by reducing the reabsorption of sodium, an event necessary for the paracellular movement of calcium across this segment. In the thick ascending limb (TAL), PTH increases calcium permeability and may increase the electrical driving force thereby increasing calcium reabsorption in the TAL. Finally, in the distal convolution, PTH acts to increase transcellular calcium reabsorption by increasing the activity and abundance of the apically expressed calcium channel TRPV5.     

A comparison of corrected serum calcium levels to ionized calcium levels in haemodialysis patients

Aberrations in calcium homeostasis are common observed in patients with chronic renal failure. Measure of total calcium does not reflect the real variation of the calcium status. The proper method to evaluate this issue in hemodialysis patients has not been completely defined. This study aimed to compare the corrected serum calcium levels to ionized calcium levels in hemodialysis patients. Thirty one patients on chronic haemodialysis admitted at the hemodialysis department were retrospectively reviewed. Calcium status was evaluated by measure of ionized levels and as a function of serum calcium levels corrected for albumin aberrations. Based on the measurement of ionized calcium and total calcium corrected, patients were classified into three categories: hypocalcemic, normocalcemic and hypercalcemic. Our result showed that the corrected serum calcium values failed to accurately classify calcium status in 41% of cases. The sensitivity and specificity of the corrected serum calcium formula to evaluate hypocalcemia were 53% and 85%, respectively. Corrected serum values underestimated the prevalence of hypocalcemia and overestimated the prevalence of normocalcemia. In total, the results obtained allow to conclude the lack of interest in the use of correction formulas. Calcium homeostasis should be evaluated by ionized calcium levels rather than as a function of serum calcium and albumin.     

Effects of acute metabolic acidosis on parathyroid hormone action and calcium mobilization.

Mechanisms through which metabolic acidosis increases calcium mobilization have been investigated in thyroparathyroidectomized rats with induction of acute metabolic acidosis by infusing NH4C1 intravenously. Acute metabolic acidosis directly raised serum calcium concentration and augmented the effect of parathyroid hormone (PTH) to raise serum calcium concentration. The same effects of metabolic acidosis were observed in rats with surgically removed intestines and bilateral nephrectomy, suggesting that acute metabolic acidosis directly increases calcium mobilization from bone and augments the effect of PTH to mobilize calcium from bone. In the kidney, acidosis directly inhibited the tubular reabsorption of calcium, but augmented the effect of PTH to increase tubular reabsorption of calcium. Acidosis had no measurable effect on calcitonin action.     

红光照射对维持性血液透析患者血磷影响的研究

目的 评估血液透析时用红光照射方法来降低血磷的效果.方法 选取60例维持性血液透析患者,分为治疗组和对照组.在进行血液透析治疗期间,采用MRX-1体外红光治疗系统照射治疗组患者体外循环管中的血液,每次照射时间持续60 min,以10次照射为一疗程;对照组患者则仍按照常规方法进行血液透析治疗.对两组患者在治疗前后均抽血测定血磷水平.结果 治疗组的30例患者透析失衡综合征症状减轻;治疗组与对照组患者在血液透析前的血磷水平差异无统计学意义(P＞0.05),而在透析后2组的血磷水平差异有统计学意义(P＜0.05).结论 对维持性血液透析患者而言,进行血液透析时用红光照射体外循环血液能够很好地起到降低血磷的效果.     

Effects of saline loading on jejunal absorption of calcium,sodium, and water,and on parathyroid hormone secretion in the rat

Summary To investigate whether intestinal calcium absorption parallels that of sodium following extracellular fluid volume expansion, the effects of saline loading on intestinal transport of calcium. sodium and water were studied in rats by perfusing jejunal loops in situ.After calcium-free saline infusion net calcium absorption was reversed similar to that of sodium and water and net secretion occurred. Concurrently, blood-to-lumen (b-l) calcium flux, measured using⁴⁵Ca, increased significantly (P<0.001). Following expansion with calcium-containing Ringer a similar reversal of net calcium, sodium and water flux was also observed. Again, the b-l calcium flux increased but to a significantly lesser extent (P<0.05). Plasma ionized calcium remained unchanged after calcium-rich Ringer loading, but decreased significantly (P<0.001) when calcium was omitted from the solution. Plasma immunoreactive parathyroid hormone was unchanged after expansion with the calcium containing solution but increased following calcium-free infusion.It is concluded that after extracellular fluid volume expansion: 1. net jejunal calcium absorption is decreased; 2. the decrease parallels that of sodium and water; 3. b-l calcium transport is enhanced to a greater degree by calcium-free Ringer infusion than by a calcium-rich solution. This difference could be the result of increased parathyroid hormone secretion.     

Differences between serum and plasma for intact parathyroid hormone measurement in patients with chronic renal failure in routine clinical practice

BACKGROUND: Parathyroid hormone (PTH) is important in the evaluation of patients with calcium metabolism disorders and/or chronic renal disease. AIMS: To assess the differences between serum and plasma PTH measurements using the Advia Centaur. METHODS: Twenty six paired serum and edetate samples from patients with chronic renal failure were analysed using the Advia Centaur. RESULTS: The EDTA results ranged from 2.3 to 76.1 pmol/litre and the Deming regression equation was: serum = 0.8927 EDTA - 0.447. The percentage difference plot had a mean difference of 13.8% (95% confidence interval, 2.2% to 25.4%; significant). The available time to separation and freezing ranged from 10 to 231 (median, 85) minutes. The correlation coefficient for the percentage difference against the time to separation and the percentage difference against the mean PTH concentration were -0.13 and -0.07, respectively. CONCLUSIONS: These results go beyond the previous controlled research conditions by showing that such differences between serum and edentate plasma exist in routine clinical practice. They also show that intra-individual PTH differences as large as 25.0% can exist on the same day between serum and edetate plasma. This may partly explain some of the variability of PTH concentrations found in some patients with chronic renal failure.     

Effects of changes in acid base and calcium concentration on fasting serum insulin, proinsulin, and glucose concentrations.

AIMS--To test the hypothesis that alterations in acid base or calcium concentration may affect proinsulin processing or the insulin secretion mechanism. METHODS--Changes in proinsulin secretion or cleavage were assessed by measuring serum intact proinsulin and immunoreactive insulin concentrations in three models of acid base and calcium disturbance: (1) subacute changes in acid base status in six volunteers who received oral placebo, ammonium chloride, or sodium bicarbonate for three five day periods; (2) acute changes in calcium concentration in eight subjects who received 25 mmol oral calcium; (3) chronic changes in calcium concentration in seven patients with primary hyperparathyroidism and five with pseudohypoparathyroidism. RESULTS--Acid base changes were confirmed by rises in serum bicarbonate concentrations (p < 0.01). No changes in serum insulin, intact proinsulin, or the proinsulin:insulin molar ratio were found. Serum calcium concentrations increased (2.49 v 2.38 mmol/l; p < 0.05) and parathyroid hormone concentrations decreased (1.1 v 1.9 pmol/l; p < 0.01) two hours after acute calcium loading. There were no significant differences in serum glucose, insulin, or intact proinsulin concentrations. Fasting proinsulin concentrations were significantly lower in the hyperparathyroid group (1.1 v 2.1 pmol/l; p < 0.05) and increased significantly after parathyroidectomy (2.1 v 1.1 pmol/l; p < 0.05). CONCLUSIONS--The results indicate that subacute acid base changes do not affect proinsulin cleavage. Although acute calcium loading has no demonstrable effect, chronic hypercalcaemia may influence the mechanism of insulin secretion.     

Effects of estrogen, raloxifene, and hormone replacement therapy on serum C-reactive protein and homocysteine levels

OBJECTIVES: To investigate the effects of conjugated equine estrogen (CEE), CEE plus medroxyprogesterone acetate (MPA), CEE plus Nomegestrol acetate (NA), and raloxifene on serum high sensitivity C-reactive protein (hs-CRP) and homocysteine (Hcy) levels in healthy postmenopausal women. MATERIALS: One hundred seven healthy postmenopausal women were recruited in a prospective, randomized, and placebo-controlled 6 months study. Of these, 18 were hysterectomized and received daily oral 0.625 mg CEE. Eighty nine non-hysterectomized women were randomly allocated to one of four groups: a group (22 patients) treated with CEE, 0.625 mg/daily plus MPA 2.5 mg/daily; a group (22 patients) treated with CEE, 0.625 mg/daily plus NA 5 mg/daily; a group (23 patients) treated with raloxifene hydrochloride, 60 mg once daily; and a placebo group (22 patients). Hcy and hs-CRP were measured at baseline and at 3 and 6 months. RESULTS: CEE (20%, P=0.03) and CEE+MPA (59%, P=0.006) increased serum hs-CRP levels significantly, whereas CEE+NA decreased serum hs-CRP by 25% (P=0.01). Raloxifene had no significant effect on serum hs-CRP levels during and after the treatment. In all active treatment groups serum Hcy levels decreased significantly compared to baseline and placebo. CONCLUSIONS: Conjugated equine estrogen, hormone replacement therapies, and raloxifene lower serum Hcy levels to a comparable extent in postmenopausal women. Hs-CRP, as a cardiovascular risk factor, is not influenced by raloxifene, whereas CEE and CEE plus MPA significantly increase hs-CRP levels. Treatment with CEE plus NA reduces serum hs-CRP levels.     

Effects of dialyzer membrane on serum albumin levels in patients receiving hemodialysis

Biocompatibility of the dialyzer membrane has been thought to affect the nutritional status in patients receiving chronic hemodialysis. In a series of patients treated in an outpatient dialysis unit, serum albumin was measured before and after changing the dialyzer membrane from one of cellulose to one of polysulfone. There were 48 patients (25 men and 23 women) who had been on dialysis for a mean duration of 78.6 months. The follow-up period was at least 6 months for each type of membrane. Delivered dose of dialysis was higher using the polysulfone membrane but serum albumin was not affected by a change to the more biocompatible membrane. Nutritional considerations are not important in choosing a membrane for dialysis.     

Calcium absorption in diphosphonate-treated rats: effect of parathyroid function, dietary calcium and phosphorus.

1. The role of parathyroid hormone (PTH) and 1, 25-dihydroxy-cholecalciferol (1,25-(OH)2D3) in modulation of intestinal Ca absorption was studied in rats, using disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP), which is known to reduce 1,25-(OH)2D3 formation. 2. EHDP decreased intestinal Ca absorption. This effect could be abolished by small amounts of 1,25-(OH)2D3, whereas even large doses of PTH were ineffective. EHDP also decreased Ca absorption in thyroparathyroidectomized (TPTX) rats. Therefore the effect of EHDP on 1,25-(OH)2D3 production is unlikely to be mediated through PTH. 3. The correction by PTH of the decreased Ca absorption in TPTX rats was inhibited by EHDP. Since EHDP inhibits formation of 1,25-(OH)2D3 the effect of PTH on Ca absorption is likely to be mediated through this vitamin D3 metabolite. 4. In normal rats both a low Ca and a low P diet stimulated Ca absorption. In EHDP-treated intact rats low Ca still stimulated Ca absorption, whereas the effect of low P abolished. This indicates that low Ca and low P diets affect Ca absorption through different mechanisms. 5. Intestinal adaptation to a low Ca diet was still observed in EHDP-treated TPTX rats. Thus, in the rat, intestinal adaptation to low Ca diet can occur without PTH.     

Inadequacy of dialysis, chronic inflammation and malnutrition in Nigerian patients on chronic hemodialysis

PURPOSE: To identify the extent of underdialysis, chronic inflammation and malnutrition and their interrelationships in Nigerian hemodialysis patients. METHODS: In a prospective study including 10 adult patients, (6 men, 4 women) on hemodialysis in North Central Nigeria, malnutrition was assessed by body mass index (BMI), serum albumin and prealbumin, and bioimpedance (BIA) pre-and post dialysis, inflammation was evaluated by C-reactive protein (CRP) and adequacy of dialysis was judged by frequency of the hemodialysis sessions and Kt/V urea. RESULTS: Post-dialysis BMI was 21.3 (19.9, 24.3) kg/m2 (< 20 kg/m2 in 4 patients), serum albumin 31.5 (24.0, 32.0) g/L (< 30.0 g/L in 5), serum pre-albumin 25.2 (15.3, 31.1) mg/dL (< 18.0 mg/dL in 4), serum CRP 4.8 (1.2, 11.5) mg/dL (> 1.0 mg/dL in 8), phase angle 4.2 (3.7, 5.1) degrees (< 3 degrees in 3) and body fat deficit was diagnosed by BIA in 4 patients. Weekly frequency of dialysis was 3 times in 2 patients, twice in 1 and 1.2 in one patient receiving dialysis only twice weekly). By combined frequency of dialysis and Kt/V urea values, no patient received an adequate dose of dialysis and, indeed, all patients had overt symptoms of uremia. Low body weight, low serological and BIA nutrition indices, and high CRP levels occurred in the same patients. Patients on dialysis for > 1 year had worse nutrition indices than those on dialysis for < 1 year. CONCLUSIONS: Underdialysis was universal, while poor nutrition and chronic malnutrition were found in the majority of the small number of patients studied. These three adverse conditions, which were interlinked, may be common in Nigerian hemodialysis patients, because their underlying socioeconomic causes are widespread.