New-Onset Anemia and Associated Risk of ESKD and Death in Non-Dialysis CKD Patients: A Multi-Cohort Observational Study

Background

Anemia is a common complication of chronic kidney disease (CKD), but its incidence in nephrology settings is poorly investigated. Similarly, the risks of adverse outcomes associated with new-onset anemia are not known.

Methods

We performed a pooled analysis of three observational cohort studies including 1031 non-anemic CKD patients with eGFR <60 mL/min/1.73 m² regularly followed in renal clinics. We estimated the incidence of mild anemia (hemoglobin 11–12 g/dL in women and 11–13 g/dL in men) and severe anemia (hemoglobin <11 g/dL or use of erythropoiesis-stimulating agents) during a 3-year follow-up period. Thereafter we estimated the risk of end-stage kidney disease (ESKD) and all-cause death associated with new-onset mild and severe anemia.

Results

The mean age was 63 ± 14 years, 60% were men and 20% had diabetes. The mean estimated glomerular filtration rate (eGFR) was 37 ± 13 mL/min/1.73 m² and the median proteinuria was 0.4 g/day [interquartile range (IQR) 0.1–1.1]. The incidence of mild and severe anemia was 13.7/100 patients-year and 6.2/100 patients-year, respectively. Basal predictors of either mild or severe anemia were diabetes, lower hemoglobin, higher serum phosphate, eGFR <30 mL/min/1.73 m² and proteinuria >0.50 g/day. Male sex, moderate CKD (eGFR 30–44 mL/min/1.73 m²) and moderate proteinuria (0.15–0.50 g/day) predicted only mild anemia. The incidence of anemia increased progressively with CKD stages (from 8.77 to 76.59/100 patients-year) and the proteinuria category (from 13.99 to 25.02/100 patients-year). During a median follow-up of 3.1 years, 232 patients reached ESKD and 135 died. Compared with non-anemic patients, mild anemia was associated with a higher adjusted risk of ESKD {hazard ratio [HR] 1.42 [95% confidence interval (CI) 1.02–1.98]} and all-cause death [HR 1.55 (95% CI 1.04–2.32)]. Severe anemia was associated with an even higher risk of ESKD [HR 1.73 (95% CI 1.20–2.51)] and death [HR 1.83 (95% CI 1.05–3.19)].

Conclusions

New-onset anemia is frequent, particularly in patients with more severe renal damage and in those with diabetes mellitus. The occurrence of anemia, even of a mild degree, is associated with mortality risk and faster progression towards ESKD.

Unusual Long-Term Complication of Permanent Central venous Catheter for Hemodialysis. Review of the Literature on Mechanical Complications

The ideal dialysis access ensures adequate blood flow for dialysis, has a long life, and is associated with a low complication rate. Although no current type of access fulfills all these criteria, the native arteriovenous fistula (AVF) is close to doing so. Unfortunately, various kinds of vascular access (VA) are becoming more and more necessary to enable hemodialysis (HD). The central venous catheter (CVC), which is associated with higher morbidity and mortality, could be the only viable option to maintain permanent VA. We report an unusual complication in a patient, a 74-year-old female, who had been undergoing HD via a CVC for 14 yrs. A polyurethane CVC with a double lumen was inserted into the right internal jugular vein because an AVF was not feasible, and a polytetrafluoroethylene (PTFE) prosthesis was obstructed. In 2003, the CVC was removed due to stenosis and occlusion of the superior vena cava. A new CVC, also made of polyurethane and with a double lumen, was inserted into the left femoral vein. In January 2005, the patient reported a small rupture of about 3–4 mm located under the cuff of the CVC. For this reason, the left femoral vein had to be used, replacing the Optiflow one with a 40-cm long Tesio CVC, and the second catheter was inserted into the right femoral artery by conventional surgery. After 10 months, the patient returned once more, after the CVC in the left femoral vein had been removed because of malfunction and that the attempts to cannulate the same vein again had failed. Currently, two 70-cm long Tesio catheters implanted in the right femoral vein (whose tips almost reach the diaphragm) are used for dialysis sessions. The number of CVC implants has progressively increased amongst HD patients who are elderly, diabetic or who have been on long-term HD. The patient described in this case report is currently using a 70-cm long double Tesio catheter (single Tesio CVC in SPI silicon) placed in the right femoral vein. She has resumed therapy with dicumarol anticoagulants, maintaining INR within the 2.5–3.5 range. In conclusion, both the increase in the use of venous catheters for HD and in the survival of dialysis patients contribute towards the observation of rare complications associated with CVC use.

Prevalence and Correlates of Anemia and Uncontrolled Anemia in Chronic Hemodialysis Patients – The Campania Dialysis Registry

Background

This study investigated prevalence and correlates of anemia and uncontrolled anemia in chronic hemodialysis patients.

Methods

A cross-sectional analysis was performed on registry data for 2,746 chronic (<6 months) hemodialysis patients aged 25–84. Data collection included years of dialysis, hours of dialysis/wk, disease causing hemodialysis, body mass index (BMI), erythropoietin (EPO) treatment, hemoglobin, markers of viral hepatitis, serum albumin, calcium, and phosphorus.

Results

Prevalence was 88.7% for anemia (hemoglobin <11 g/100 mL and EPO treatment at any Hb level), 39.4% for uncontrolled anemia (hemoglobin<11 g/100 mL). Gender, years of dialysis, hereditary cystic kidney disease (HCKD), and low BMI (<24 kg/m2) were independent correlates of anemia (P<0.001). Gender, HCKD, low BMI, serum albumin and calcium were independent correlates of uncontrolled anemia (P<0.05). An interaction was found between age (not correlated with anemia and uncontrolled anemia) and the association of gender with uncontrolled anemia (P<0.05). EPO doses were higher in patients with high prevalence of uncontrolled anemia than in patients with low prevalence (i.e., women vs men, other diseases vs HCKD, low vs not-low BMI, P<0.01). Gender, years of dialysis, HCKD, BMI, serum albumin, and calcium were independent correlates of the hemoglobin/EPO dose ratio in patients on EPO treatment (P<0.05).

Conclusion

Anemia and uncontrolled anemia are more frequent in hemodialysis patients with short-term dialysis, diseases other than HCKD, low BMI, and female gender. Gender effect was lower in elderly patients. Uncontrolled anemia was also associated with low serum albumin and calcium, suggesting that these parameters are indices of EPO resistance.

[Compliance with low-protein diet in patients with chronic kidney disease]

Direct evaluation of the compliance with nutritional therapy is possible only in clinical trials while indirect methods such as self-reporting and interviews are used in clinical practice. Dietary history is the best method to evaluate nutritional habits in clinical practice; the same holds true for the compliance with low-protein diets in patients with chronic kidney disease. Other indexes to assess dietary compliance should be simple and easy to use in the clinical practice. Some of such functional and biological markers are blood urea nitrogen and serum phosphate levels (indirect markers of dietary intake), weight and body mass index (indirect markers of energy intake), and daily urinary excretion of nitrogen and sodium (indirect markers of protein and salt intake). The compliance with a low-protein diet in patients with chronic kidney disease is strongly influenced by psychosocial factors (e.g., satisfaction and comprehension), and thus by the supporting role of the physician and the dietitian, but also by the level of renal function and food characteristics. It must be pointed out that even a protein intake reduction of 0.2 g/kg/day improves blood urea nitrogen, phosphate levels, and acidosis.

[Low-protein diet in Italy today: the conclusions of the Working Group from the Italian Society of Nephrology]

The high estimated prevalence of chronic kidney disease (CKD) forcefully supports the need for collaboration among nephrologists, cardiologists, diabetologists and general practitioners, to reduce the cardiovascular risk of CKD patients and delay the start of dialysis. Many studies confirm that reducing the dietary intake of proteins improves uremia as well as acid-base and phosphorus disorders without exposing the CKD patient to the risk of malnutrition. The possibility of delaying renal death and the start of dialysis by almost one to two years is also recognized, thanks in part to the antiproteinuric effect of low-protein diets supplemented with keto acids and essential amino acids. Reducing the dietary protein intake delays the start of dialysis independently of the effect of renin-angiotensin system (RAS)-active antihypertensive drugs. Reduction of the dietary protein intake is indicated in patients with a glomerular filtration rate <25 mL/min (CKD stages 4 and 5). Some situations may, however, require an earlier switch to a low-protein diet, e.g., high proteinuria, renal function worsening at more than 5 mL/min/year, diabetes, and metabolic decompensation. If well designed and properly carried out, reduction of the dietary intake of proteins is not associated with low serum albumin levels or malnutrition, and does not affect patients death. Today, highly palatable, high-quality reduced protein preparations are widely available to reduce the protein intake of CKD patients.

[The low-protein diet in chronic kidney disease: still a valid prescription?]

Low-protein diets were originally identified as a therapeutic tool to alleviate symptoms and signs of uremia. Their prescription, however, became common in the 1980s to reduce the rate of progression of chronic kidney disease. Since then, several studies of this nonpharmacological intervention have been published. In particular, the Modification of Diet in Renal Disease (MDRD) study, which is a cornerstone of the nephrology literature, was specifically aimed at verifying the effectiveness of low-protein diets; the results, however, were negative. Therefore, the diet issue progressively disappeared from scientific meetings and journals, and as a consequence also its use in clinical practice has diminished. The aim of this paper is to describe the state of the art of low-protein diets almost 15 years from the publication of the MDRD study.

[Low-protein dietary therapy in patients with chronic kidney disease]

Several prospective studies and meta-analyses including the recent Cochrane meta-analysis have demonstrated that reducing the protein content in the diet delays renal death and the start of dialysis in patients with chronic kidney disease (CKD). Reducing the dietary protein intake offers other benefits such as lowering accumulation of uremic toxins and circulating phosphates and improving symptoms and metabolic derangements. Following the publication of the Cochrane meta-analysis, some of the most renowned experts in Italy on dietary therapy in the CKD patient established a working group within the Italian Society of Nephrology (SIN), the ''Nephrontieres'' project. The current supplement of GIN presents the views of the members of the ''Nephrontieres'' group on a range of issues related to dietary therapy in CKD. A CME program for Italian nephrologists also originated from the collaborative work of the group.

[Prevalence of chronic kidney disease]

The prevalence of chronic kidney disease (CKD), especially the early stages, is still not exactly known. This is also true for CKD stage 3, when cardiovascular and other major complications generally appear. The NANHES data have shown a steady increase in the prevalence of CKD 3 up to 7.7% in 2004. Chronic kidney disease and renal failure are underdiagnosed all over the world. In Italy, prevalence estimates for stage 3 to 5 CKD are around 4 million yet, less than 30% of these subjects are believed to be followed at nephrology clinics. This means that in Italy for every dialyzed patient there are about 85 individuals with possibly progressive kidney disease, while fewer than five (mainly stage 4 and 5 patients) are actually followed by a nephrologist.

Prevalence and correlates of anemia and uncontrolled anemia in chronic hemodialysis patients--the Campania Dialysis Registry

BACKGROUND

This study investigated prevalence and correlates of anemia and uncontrolled anemia in chronic hemodialysis patients.

METHODS

A cross-sectional analysis was performed on registry data for 2,746 chronic (>6 months) hemodialysis patients aged 25-84. Data collection included years of dialysis, hours of dialysis/wk, disease causing hemodialysis, body mass index (BMI), erythropoietin (EPO) treatment, hemoglobin, markers of viral hepatitis, serum albumin, calcium, and phosphorus.

RESULTS

Prevalence was 88.7% for anemia (hemoglobin <11 g/100 mL and EPO treatment at any Hb level), 39.4% for uncontrolled anemia (hemoglobin<11 g/100 mL). Gender, years of dialysis, hereditary cystic kidney disease (HCKD), and low BMI (<24 kg/m2) were independent correlates of anemia (P<0.001). Gender, HCKD, low BMI, serum albumin and calcium were independent correlates of uncontrolled anemia (P<0.05). An interaction was found between age (not correlated with anemia and uncontrolled anemia) and the association of gender with uncontrolled anemia (P<0.05). EPO doses were higher in patients with high prevalence of uncontrolled anemia than in patients with low prevalence (i.e., women vs men, other diseases vs HCKD, low vs not-low BMI, P<0.01). Gender, years of dialysis, HCKD, BMI, serum albumin, and calcium were independent correlates of the hemoglobin/EPO dose ratio in patients on EPO treatment (P<0.05).

CONCLUSION

Anemia and uncontrolled anemia are more frequent in hemodialysis patients with shortterm dialysis, diseases other than HCKD, low BMI, and female gender. Gender effect was lower in elderly patients. Uncontrolled anemia was also associated with low serum albumin and calcium, suggesting that these parameters are indices of EPO resistance.

Very low protein diet supplemented with ketoanalogs improves blood pressure control in chronic kidney disease

Blood pressure (BP) is hardly controlled in chronic kidney disease (CKD). We compared the effect of very low protein diet (VLPD) supplemented with ketoanalogs of essential amino acids (0.35 g/kg/day), low protein diet (LPD, 0.60 g/kg/day), and free diet (FD) on BP in patients with CKD stages 4 and 5. Vegetable proteins were higher in VLPD (66%) than in LPD (48%). LPD was prescribed to 110 consecutive patients; after run-in, they were invited to start VLPD. Thirty subjects accepted; 57 decided to continue LPD; 23 refused either diet (FD group). At baseline, protein intake (g/kg/day) was 0.79+/-0.09 in VLPD, 0.78+/-0.11 in LPD, and 1.11+/-0.18 in FD (P<0.0001). After 6 months, protein intake was lower in VLPD than LPD and FD (0.54+/-0.11, 0.78+/-0.10, and 1.04+/-0.21 g/kg/day, respectively; P<0.0001). BP diminished only in VLPD, from 143+/-19/84+/-10 to 128+/-16/78+/-7 mm Hg (P<0.0001), despite reduction of antihypertensive drugs (from 2.6+/-1.1 to 1.8+/-1.2; P<0.001). Urinary urea excretion directly correlated with urinary sodium excretion, which diminished in VLPD (from 181+/-32 to 131+/-36 mEq/day; P<0.001). At multiple regression analysis (R2=0.270, P<0.0001), BP results independently related to urinary sodium excretion (P=0.023) and VLPD prescription (P=0.003), but not to the level of protein intake. Thus, in moderate to advanced CKD, VLPD has an antihypertensive effect likely due to reduction of salt intake, type of proteins, and ketoanalogs supplementation, independent of actual protein intake.

[Bioelectrical analysis in uremic patients]

Bioelectrical analysis (BIA) is an easy, repeatable, low cost, operator-independent method. BIA obtains two different goals, i.e. body water content evaluation, by the RXc Graph or the BIVA Z score and morbidity and mortality predictions by the phase angle. Therefore, BIA can be considered as part of the clinical examination for the evaluation of both hydration and nutritional status.

Management of hypertension in chronic kidney disease: the Italian multicentric study

BACKGROUND

Guidelines have indicated the achievement of blood pressure target (BP <130/80 mmHg) as a priority in the conservative treatment of chronic kidney disease (CKD), but the current implementation of these recommendations in clinical practice is unknown.

METHODS

We assessed control rates, treatment and clinical correlates of hypertension in 1201 adult non-dialyzed CKD patients followed up by a nephrologist for at least 6 months.

RESULTS

Estimated glomerular filtration rate (GFR) was 32 (SD 15) mL/min/1.73 m2. BP target was not achieved in 88% of patients (95% confidence interval (95% CI): 86-90%). In 84% of patients, BP levels were also above the target at the first visit to the nephrology unit 4.5 yrs previously. The risk of not achieving BP target during the nephro-logy follow-up was associated with older age (odds ratio (OR): 1.24, 95% CI 1.06-1.45, p=0.008), diabetes (OR: 2.25, 95% CI 1.20-4.20, p=0.011), and the duration of hypertension (OR: 1.13, 95% CI 1.02-1.24, p=0.016). Among patients with uncontrolled BP, about 70% received multidrug antihypertensive therapy including renin-angiotensin system (RAS) inhibitors; conversely, diuretic treatment was prescribed in a minority of patients (37%), and at insufficient doses in half the cases, despite the insufficient implementation of a low salt diet (18%).

CONCLUSIONS

BP target was not reached in most CKD patients routinely seen in the renal clinics. The main barrier to guideline implementation is possibly the inadequate treatment of extracellular volume expansion despite the large prevalence of factors, such as older age and diabetes, which further enhance the intrinsic BP salt sensitivity of CKD.

[Daily nutrient intake in hemodialysis]

BACKGROUND

Although there is a higher nutrient requirement, food intake in haemodialysis patients is often inadequate. Protein nitrogen appearance (PNA) indirectly estimates the mean protein intake during the short interdialysis period, but it does not measure the daily nutrient intake, which is generally unknown. We carried out a longitudinal study aimed at estimating the daily nutrient intake and its relationship with the nutritional status of haemodialysis patients.

METHODS

We selected 28 haemodialysis patients with adequate nutritional status and no evidence of risk-factor for malnutrition. Patients were treated with biocompatible membranes, low-flux and high bicarbonate dialysis, Kt/V > 1.2, PNA > 1.1 g/kg/day and erythropoietin. We measured every four months daily PNA, protein and calorie intake (DPI, DCI) as well as weight gain (WG) during an entire week for one-year. The nutritional status was assessed by biochemical and BIA markers.

RESULTS

Twenty seven subjects (8 F, 19 M; age 57.1 +- 2.7 yeas; dialysis age 105 +- 13 months) completed the trial. The mean interdialytic PNA did not change in both long- and short-interdialysis periods, resulting in the "normal" range (> 1.1 g/kg/day); however, daily levels of protein and calorie intake were significantly reduced on the third day during the long interdialysis interval. Eight patients showed time-averaged values of DPI and DCI lower than 0.8 g/kg/day and 25 Kcal/kg/day, respectively, on the third day (LOW group), values that were associated with similar changes in WG. Such a highly reduced nutrient intake during the third interdialysis day was associated with a normal PNA value (1.23 +- 0.05 g/kg/day vs 1.30 +- 0.06 in CON, NS) when measured during the short interdialysis period (S), just as it is in clinical practice; in contrast, when the PNA value was measured during the long interdialysis period it was found to be significantly reduced (1.07 +- 0.08 g/kg/day vs 1.37 +- 0.06 in CON, p < 0.05 and vs S, p < 0.05). During the study, the body weight progressively decreased from 68.0 +- 5.5 to 65.8 +- 5.9 kg (p < 0.05) in the LOW group, due to the decrease in lean body mass, as suggested by the reduction in serum creatinine (9.2 +- 1.1 vs 8.1 +- 0.7 mg/dL, p < 0.05), creatinine generation (835 +- 155 vs 723 +- 106 mg/die, p < 0.05) and serum albumin (3.96 +- 0.07 vs 3.66 +- 0.06 g/dL, p < 0.05). Moreover, reactance and phase angle declined in the LOW group (from 54 +- 4 to 44 +- 3 ohms, p < 0.05 and 5.5 +- 0.3 to 4.5 +- 0.3 degrees, p < 0.05, respectively). At the end of the study the nutritional status in the LOW group was reduced as compared to the CON group.

CONCLUSIONS

In stable, well-nourished haemodialysis patients, in absence of known risk factors for malnutrition, the daily nutrient intake is variable and progressively reduce during the interdialytic interval. The measurement of interdialytic PNA, as is done in clinical practice, does not enable the discovery of such abnormal eating behaviour; the low daily nutrient intake, on the contrary, can be evidenced by the daily measurement of either PNA or weight gain, and it can also be inferred by the reduced PNA during the long interdialytic period. Finally, the persistent reduction in nutrient intake below the threshold of 0.8 g/kg/day of proteins and 25 Kcal/kg/day one day a week, is capable of inducing body protein wasting and moderate impairment of the nutritional status.

The prediction of single-frequency BIA variables from individual characteristics

To define whether reference values for bioimpedance analysis (BIA) can be predicted in healthy individuals, individual characteristics and BIA variables (resistance index=height(2)/parallel resistance and reactance index= height(2)/parallel reactance) were evaluated in non-obese healthy individuals: 863 men and 769 women with an age range 20-70 years and body mass index (BMI) 19.0-29.9 kg/m(2). The following predictive equations were obtained using multiple regression analysis:Resistance index (cm(2)/ohm)Males 21.06 + 0.087xage + 1.091xweight -1.801xBMI,Females 20.35 + 0.037xage + 0.878xweight - 1.343xBMIReactance index (cm(2)/ohm)Males 0.57 + 0.117xweight - 0.096xBMIFemales 1.42 + 0.078xweight - 0.075xBMIIn conclusion, reference BIA values seem to be reasonably predicted based on individual characteristics.

[Usefulness of directional power Doppler sonography in the ultrasound-guided percutaneous native kidney biopsy]

BACKGROUND

The study was aimed to analyze the pattern of bleeding throughout the kidney tissue after renal biopsy and evaluate its relationship with the onset of renal biopsy side effects by using directional power-Doppler sonography.

PATIENTS

Eighty-five consecutive subjects with clinical evidence of renal disease underwent to percutaneous renal biopsy using directional power Doppler sonography. In each patient, the pattern of kidney hemorrhage immediately after the renal biopsy was evaluated.

RESULTS

Fifty-seven patients, representing 67% of all biopsies performed, evidenced renal bleeding lasting 5.3+/-5.7 min; fifty-five patients, representing 65% of all biopsies, developed a post biopsy hematoma (x = 2.9+/-2.0 cm); 36% of patients developed a perirenal hematoma (x = 1.8+/-2.1 cm). A subcapsular hematoma was experienced by 45% of patients (x = 2.7+/-1.1 cm); 16% of these patients had a combined perirenal-subcapsular hematoma; 5% of hematomas were larger than 5 cm. Hematoma dimensions were related to the length of bleeding (r = 0.6331; p < 0.0001). Hemoglobin and hematocrit levels significantly reduced from 12.7+/-2.3 g/dL to 11.7+/-2.3 g/dL (-7%, p < 0.0001) and 37.6+/-6.5% to 35.4+/-6.5% (-6%, p < 0.0001) respectively, and such variations were related to the hematoma size (Delta Hb: r = -0.5171; p < 0.0001; Delta Htc: r = -0.3465; p < 0.0001).

CONCLUSIONS

This study demonstrates that directional power Doppler sonography allows medical personnel to clearly evidence all renal biopsy-related side effects and identify, through the evaluation of renal bleeding immediately after the kidney biopsy, those patients who will develop renal hematomas.

[Regional epidemiology of chronic nephropathies: referral to nephrologist and initiation of dialysis]

BACKGROUND

The epidemiology of pre-dialysis chronic nephropathies (CN) in well-defined contexts is essential to prevent delays in delivering appropriate care.

METHODS

The registration of consecutive patients in seven out-patient and four in-patient dialysis centers of Basilicata (2001) formed a retrospective study on clinical charts and dialysis registers integrated with ad hoc data.

RESULTS

Newly observed outpatients (I) numbered 328; prevalent patients (P) numbered 343. The age and gender of both I and P patients was similar (males: 60%, age media: 67 yr). In 316 I patients with creatinine (mean Cr: 2.3 mg/dL), the mean filtration rate (GFR) was 40.9 mL/min/1.73 m2: 13.6% were in advanced stage (S5) of GFR (<15 mL/min), 23.4% in S4/severe (15-29), 45.6% in S3/moderate (30-59), 10.8% in S2/mild (60-89), and 6.6% in S1 (>90). When compared to I patients, P patients had a mean GFR of 35.0 mL/min; S4+S5 was 48% (vs. 37%); hypertension 68% (vs. 58%); vasculopathies 15% (vs. 10%); coronary disease 10% (vs. 4%); erythropoietin 13% (vs. 7%); and low-protein diet 34% (vs. 20%) (p<0.01). Of 316 I patients, 117 in S5+S4 ('late referral' 37%) had a (mean) GFR of 18.4 mL/min, Cr 3.7 mg/dL, and were aged 70 yrs (vs. 64 yrs for 'early referral'). Of 53 new patients on dialysis, 26 (49%) were seen for the first time <6 months prior to starting (mean age: 71 yr vs. 62; female 58% vs. 26%; complications 50% vs. 17%).

CONCLUSIONS

In this population, age-related factors are associated with late referral. Although sociodemographic variables depend on local contexts, these results are consistent with similar international studies. Social and cultural factors may influence physicians to postpone referring patients to a nephrologist, independently of clinical conditions.

[Can anemia be corrected in hemodialysis patients with thalassaemia minor? ]

BACKGROUND

Anemia is an important negative prognostic factor for dialysis patients, whose correction reduces hospitalisation and mortality. Besides, the presence of the thalassaemia minor (Thal-m) in haemodialysed patients causes erythropoietin resistance and more serious anemia. The goal of this study is the correction of anemia (Hb >11 g/dL) in haemodialysed Thal-m patients.

MATERIALS AND METHODS

Multicentric, prospective and controlled 12-month study for the correction of anemia (up to values ranging from 11 to 12 g/dL) followed by a 12-month observation period. Ten Thal-m patients with inadequate anemia correction were studied after therapy with rHuEPO. Their age at the beginning of the study was 62.8+/-4 years while their dialytic age was 89+/-20 months.

RESULTS

During the study we observed no changes in dry weight (p=NS), no increase in interdialytic weight (p=NS), cardiac frequency (p=NS), serum albumin (p=NS), serum aluminium (p=NS), PTH (p=NS), URR (p=NS), flow FAV (p=NS), TSAT (p=NS) and ferritin (p=NS) (maintained at their optimal values by means of intravenous therapy with trivalent iron. The hypotensive therapy (1.6 drug/patient/year) required no modifications during the 24-month study. The rHuEPO dose varied from 200.3+/-94.3 to 286.6+/-116.2, 317.0+/-119.5, 446.9+/-142.3, and 407.0+/-130.5 U/kg/wk (p < 0.0001 vs. initial value) (from the start to the 3rd, 6th, 9th and 12th month, respectively). The dose was subsequently reduced to 385.2+/-119.7 U/kg/wk at 15 months (p < 0.0001 vs. initial value) and remained unchanged until the end of the study. Simultaneously, the Hb values at corresponding times were 9.2+/-0.9, 9.4+/-1.1, 10.2+/-1.4, 10.9+/-1.5, 11.2+/-1.4 and 11.0+/-1.4 (p=0.002 vs. initial value). The correction of anemia produced progressive reduction in cardiac mass from 141+/-12 to 120+/-10 and 110+/-8 g/mq at the beginning, 12th month and 24th month (p < 0.0001), respectively. During the study the hospitalisation time was 4.3+/-1.2 day/patient/year during the 3-month run-in period, 3.4+/-1.4 day/patient/year during the first year, and 3.1+/-1.1 day/patient/year during the second year (p=0.098).

CONCLUSIONS

In conclusion we can say that the question of Thal-m in dialysis patients cannot be ignored or underestimated. The rHuEPO dosage in these patients must be reassessed (a dose of 450 U/kg/wk corresponding to approximately 60,000 units/week is acceptable and does not produce an increase in side effects if the correction is done gradually); moreover, other factors responsible for EPO-resistance must be eliminated (hyperthyroidism, aluminium intoxication, iron overloaded or deficiency).

[Acute and chronic effects of standard hemodialysis and soft hemodiafiltration on interdialytic serum phosphate levels]

INTRODUCTION

The dialytic management of hyper-phosphoremia, which is inadequate because of insufficient intra-dialytic removal of phosphate (P), is further limited by PDR-P, i.e. the significant increase in serum P levels during the early postdialytic period. Patients and methods. To investigate the effects of enhanced P removal by haemodiafiltration on the inter-dialytic phosphoremia, we studied 12 uremic patients that were switched, with cross-over randomised modality, to a single session of standard hemodialysis (HD) and hemodiafiltration (HDF) (Acute Study). Blood samples were obtained before the treatment, at the end (T0), after 30, 60, 90 and 120 minutes, and at 24, 48 and 68 hours. During both dialytic treatments the whole effluent dialysate was collected to evaluate the intradialytic removal of P. Thereafter, patients were randomised to receive either HD or HDF for three months, in the presence of constantly similar Kt/V, food intake and dose of phosphate binder (Chronic Study).

RESULTS

Acute Study. Compared to HD, P removal in HDF was about 44% greater in the presence of identical predialytic P levels (6.0+/-0.2 and 5.9+/-0.4 mg/dl) and Kt/V (1.35+/-0.06 and 1.34+/-0.05); however, the inter-dialytic decline of serum P levels did not differ (-50+/-3% versus -42+/-3%, p=0.098). In HDF, PDR-P was faster (30 min versus 90 min) and better (at T120: +69+/-6% versus +31+/-4%, p<0.001). The higher P levels were maintained throughout the inter-dialytic period whereas Ca x P changed in parallel. Chronic Study. During the three months, pre-dialytic serum P diminished in HDF (from 5.8+/-0.2 to 4.4+/-0.3 mg/dl, p<0.05), while it remained unchanged in HD. A similar pattern of changes was detected in Ca x P.

CONCLUSIONS

Enhancement of P removal, acutely amplifies the extent of PDR-P, but allows better control of Ca-P homeostasis in the medium term. This effect is likely to be dependent on the enhanced mobilisation of phosphate from a deep compartment.

[Thalassaemia minor: national survey of uraemic patients under substitutive treatment]

BACKGROUND

The incidence of thalassaemia minor in end-stage renal disease patients is similar to that of the general population. Both these conditions are characterized by anaemia, but the underlying pathophysiology is quite different. Current literature lacks an adequate clinical survey of haemodialysis patients with thalassaemia minor.

METHODS

The prevalence of thalassaemia minor (thal-m) in haemodialysis patients was assessed by a national survey collecting general information as well as clinical and haematological parameters. Data were also collected on the use of recombinant erythropoietin in these subjects. A dedicated questionnaire was sent to all Italian dialysis units.

RESULTS

Only 116/705 dialysis units returned the questionnaire (16.4%): 33 units did not have any patients affected by thalassaemia minor. No response was obtained from six Italian regions whereas ten regions returned only partial answers. The response from four regions was satisfactory (20%) while the completed questionnaire was returned by all units in only two small regions. A total of 7731 ESRD patients were collected, 240 (3.1%) were also affected by thal-m, 142 males and 98 females. In the four regions with the highest response rates, Calabria 45%, Puglia 65%, Basilicata and Molise 100%, the prevalence of thal-m were 3.68%, 4.56%, 3.3% and 1%, respectively. A total of 3623 uraemic patients (47% of all enrolled subjects) were collected from these four regions. Here is the patient geographic distribution: northern Italy 2.16% (response rate of 9.44%); central Italy 1.69% (response rate of 7.64%), southern Italy 3.77% (response rate of 29.46%). The age range of thal-m patients was 17 to 90 years, the time spent on dialysis was between 3 and 384 months, the body weight was between 35 and 93 kg, the Hb value was between 6.2 and 13.6 g/dl, and the Htc value was between 19 and 44%. A total of 230 thal-m patients were on haemodialysis while 10 patients were on peritoneal dialysis (4.2%). The mean haemoglobin level for the thal-m group was 9.8+/-1.4 g/dl and for the control group the value was 11.4+/-1.4 g/dl (p < 0.0001). The use of rhEPO was on the average 7659+/-6256 u/wk for the thal-m and 4378+/-4435 u/wk for the control group (p < 0.0001). The bodyweight was 129+/-105 u/kg/wk (range 0-370). Finally, 17.9% of the thal-m patient did not use rhEPO, their Hb value was 10.66+/-1.67 g/dl (range 8.2-13). No patient went over 30 thousand units and only 4 had such dosage in therapy. The 12.1% thal-m patients with Hb < 10 g/dl did not use rhEPO. The need for rhEPO per gram of Hb was 796+/-722 u/wk in thal-m patients and 416+/-449 U/wk in control patients (p < 0.0001). Uraemic anaemia was corrected with 4.8 million red blood cells in the control group and with about 7.7 million red blood cells in the thal-m group.

CONCLUSIONS

Data from this national survey, although incomplete, show that rHuEpo is less effective in these patients and its use does not seems to be correct. It is important to emphasise that recent Guidelines do not recommend neither a specific treatment for these patients nor the use of r-HuEpo. However, it should also be underscored that most thal-m patients do not reach the target Hb level suggested by the National Guidelines for the general population in chronic dialysis.

Successful use of central venous catheter as permanent hemodialysis access: 84-month follow-Up in lucania

Cuffed tunneled venous access catheters are commonly used for temporary and permanent access in hemodialysis (HD) patients. These catheters serve an essential role in providing permanent access in subjects in whom all other access options have been exhausted. The predominant complications are catheter thrombosis, catheter fibrin sheating and infection. The aim of this study was to evaluate long-term survival and complications of permanent venous catheters (PVC) placed for the purpose of HD during the period from January 1992 to December 1998, at the Dialysis Units of Lucania (a southern Italian region). A total of 98 PVC were placed in 88 patients during this period. The catheters used were of three types: (a) 72 VasCath Soft Cell catheters (Bard Instrument Company, Toronto, Ont., Canada); (b) 22 PermCath catheters (Quinton Instrument Company, Seattle, Wash., USA), and (c) 4 Tesio catheters (Bellco SpA, Mirandola, Italy). Survival curves of catheters were calculated using the Kaplan-Meier product-limit estimator. The patient survival was 60% at the 78th month. Actually, 52 patients (27 males, 25 females) are still alive: 15 (26.9%) of these patients have diabetes mellitus and 1 has been transplanted. The actuarial survival rate of PVC was 89% in the whole population studied and 82% in subjects alive after 84 months. Twenty-five patients (28.4%) had PVC as the first reliable vascular access. Long-term complications occurred 27 times (1 episode every 44.81 month/patient) as: breakage (3.1%); thrombosis (10.2%); displacement (2.0%); subcutaneous tunnel bleeding (3.1%); inadequate blood flow (7.1%), and infection (10.2%). In conclusion, our data confirm that PVC might represent an effective long-term blood access route for HD. Again, PVC are getting the access of choice for selected patients (i.e., older subjects with cardiovascular diseases and cancer patients) and are enjoying a dramatic increase in use for subjects who are terrified of repetitive venopuncture.

Abnormalities of bioimpedance measures in overweight and obese hemodialyzed patients

BACKGROUND

The body composition in overweight and obese hemodialyzed patients (HD) remains ill-defined. This study evaluates in HD patients the influence of body size, as indicated by body mass index (BMI, kg/m(2)), on body composition by measuring bioimpedance analysis (BIA)-derived variables (phase angle (PA), fat-free mass (FFM) and body cell mass (BCM).

METHODS

We studied 50 Caucasian patients (mean age 62.8+/-9.2 y) on standard bicarbonate hemodialysis for at least 12 months who regularly achieved dry weight in post-HD, received similar dialysis doses and were free from inflammation/infection. Thirty-eight gender- and age-matched healthy subjects were included as controls (CON). Both HD and CON were divided into three groups on the basis of their BMI(kg/m2) 18.5-24.9, normal-weight (NW); 25-29.9, overweight (OW); and > or =30, obese (OB). In HD patients, BIA was performed 30 min after the end of dialysis.

RESULTS

Seven patients were obese (12%) while 16 were overweight (32%); in CON, 12 were obese (31%) and 12 overweight (31%). BIA-measured extracellular water was comparable in all groups. PA, which was similar in normal-weight HD and CON (6.2+/-0.9 degrees and 6.3+/-0.8 degrees ), decreased in OW- and OB-HD patients (5.3+/-1.0 degrees and 5.2+/-0.6 degrees, respectively; P<0.05 vs NW-HD) while it was unchanged in OW- and OB-CON (6.1+/-0.8 degrees and 5.9+/-0.5 degrees, P<0.05 vs respective HD groups). In OW and OB patients, the lower PA values were coupled with a major reduction of BIA-derived percentage BCM and FFM (P<0.05 vs NW-HD, and vs OW- and OB-CON). In patients, PA and BCM correlated with anthropometry-measured FFM. Of note, serum albumin and protein catabolic rate were significantly reduced in OB patients.

CONCLUSION

In overweight and obese HD patients, BIA-derived FFM, BCM and PA are significantly lower with respect to normal-weight patients and BMI-matched controls. These abnormalities of body composition are coupled with reduction of anthropometric measures of lean mass and a decrease of protein intake that, however, becomes significant only in the obese. We therefore suggest that overweight and obese HD patients are at risk of protein malnutrition in spite of excessive energy intake. BIA may be considered as a useful diagnostic tool to detect such a condition early.

Effects of water hardness on urinary risk factors for kidney stones in patients with idiopathic nephrolithiasis

Both amount and timing of dietary calcium intake influence the recurrence of renal calcium stones. We have evaluated whether the hardness of extra meal drinking water modifies the risk for calcium stones. The urinary levels of calcium, oxalate and citrate, i.e., the main urinary risk factors for calcium stones, were measured in 18 patients with idiopathic nephrolithiasis, maintained at fixed dietary intake of calcium (800 mg/day), after drinking for 1 week 2 liters per day, between meals, of tap water and at the end of 1 week of the same amount of bottled hard (Ca2+ 255 mg/l) or soft (Ca2+ 22 mg/l, Fiuggi water) water, in a double-blind randomized, crossover fashion. As compared with both tap and soft water, hard water was associated with a significant 50% increase of the urinary calcium concentration in the absence of changes of oxalate excretion; the calcium-citrate index revealed a significant threefold increase during ingestion of hard water as compared with respect to soft water (Fiuggi water), making the latter preferable even when compared with tap water. This study suggests that, in the preventive approach to calcium nephrolithiasis, the extra meal intake of soft water is preferable to hard water, since it is associated with a lower risk for recurrence of calcium stones.

Bioelectrical impedance measurement: errors and artifacts

Bioelectrical impedance analysis (BIA) allows simple noninvasive estimation of body water, and it could potentially be a very useful technique for clinical monitoring and study of abnormalities of body water. It has been shown that the total body impedance is dominated by the arm (46%) and leg (44%). The trunk, which represents an average of 46% of the body weight, accounts for only 10% of the total impedance. The objective of the current study was to determine the errors in prediction of body composition from BIA when applied to dialysis patients with measurement on the nondominant arm, postural changes, muscular contractions or cramps, monolateral lymphoedema, arteriovenous fistula, central venous catheter, or vascular graft. We studied 20 healthy subjects, 20 uremics on chronic hemodialysis, 3 uremics with fever (body temperature >38.5 degrees C), 3 uremics with cramps, 3 patients with monolateral lymphoedema of an arm, and 3 patients with a prosthetic fistula on an arm. The results of our study show different values of total body water (TBW) derived by BIA measurements effected on supine or standing position (percentage rate variation = 1.1% to 1.6%), or effected during fever (6%), during cramps (-0.73%), with lymphoedema (25%), or in presence of a native arteriovenous fistula, a catheter in a central vein, or a graft (between -24% and +4%). We concluded that a significant error may occur in the measurement of body composition from whole body BIA when performed in the reported cases.

Randomized, double-blind, placebo-controlled study of arginine supplementation in chronic renal failure

BACKGROUND

Supplementation with L-arginine (ARG) strikingly ameliorates proteinuria and glomerulosclerosis in remnant rats by overcoming nitric oxide (NO) deficiency. Whether or not the same holds true in humans is unknown. This study aimed at evaluating the effects of ARG on the NO system and renal function in proteinuric patients with moderate chronic renal failure (CRF).

METHODS

We measured plasma arginine, urinary and plasma NO3 (an index of NO synthesis), and urinary cGMP (an intracellular mediator of NO), as well as proteinuria and renal functional reserve (RFR) in CRF patients orally treated for six months with either ARG (0.2 g/kg body wt/day, CRF-A group) or the control vehicle (CRF-C). Normal subjects (NOR) were also included for basal comparisons.

RESULTS

In CRF patients at baseline, plasma arginine was within the normal range; similarly, the urinary excretion of NO3 was comparable to the NOR value (CRF, 0. 440 +/- 0.02; NOR, 0.537 +/- 0.08 micromol/min, P = NS). The plasma NO3 levels were higher than in NOR (CRF, 74 +/- 6; NOR, 27 +/- 2 micromol/liter, P < 0.001), and consequently the renal clearance of NO3 resulted as being reduced. During the six months of treatment, although a remarkable steadiness of ARG and NO3 levels was detected in the CRF-C group, the CRF-A group was characterized by a marked and immediate increase of plasma ARG. This was associated, however, with a delayed increment in urinary and plasma NO3 levels and no change in urinary cGMP. In CRF-A, as in CRF-C, blood pressure, proteinuria, glomerular filtration rate, and renal plasma flow did not vary. Likewise, RFR, which was reduced at baseline in CRF, did not improve after ARG.

CONCLUSIONS

In moderate CRF, the tonic release of NO is constant and, likely, not impaired, and ARG supplementation does not lead to an enhancement of NO activity, thus resulting in no renal effect.

Early impairment of renal hemodynamic reserve in patients with asymptomatic heart failure is restored by angiotensin II antagonism

BACKGROUND

The early/asymptomatic stages of heart failure (HF) are characterized by sodium retention secondary to derangement of sodium reabsorption at the proximal nephron level. Because this phenomenon is reversed by ACE inhibition, abnormalities of renal sodium handling may depend on intrarenal changes of angiotensin II (AII)/nitric oxide (NO) levels. Renal hemodynamic reserve (ie, the glomerular vasodilatory response to amino acid infusion) has been proposed as a reliable test to assess in vivo AII/NO balance.

METHODS AND RESULTS

In this study, the effects of 6 weeks of treatment with 5 mg/d of enalapril or with 50 mg/d of losartan on systemic hemodynamics and renal function were assessed, at baseline and after amino acid infusion (AA), in patients with mild HF (NYHA class I) and in healthy volunteers. Untreated HF patients showed a basal renal function comparable to that of healthy subjects. After AA, glomerular filtration rate and renal plasma flow significantly increased in healthy subjects (+29.0% and +30.4%, respectively), whereas no vasodilatory response was observed in HF. Although they did not affect basal renal hemodynamics, both enalapril and losartan restored a normal response to AA in HF patients. Blood pressure and heart rate were comparable in HF subjects and healthy subjects at baseline and were not modified by either treatment. Left ventricular ejection fraction was depressed in HF but did not change after either drug. Urinary excretions of cGMP and nitrate (indexes of NO activity in the kidney), comparable in healthy subjects and in HF patients, were unchanged by either enalapril or losartan and did not correlate with renal reserve.

CONCLUSIONS

(1) Renal functional reserve is absent in patients with early/asymptomatic HF and normal renal function and (2) both enalapril and losartan restore a normal vasodilatory response to AA in these patients without affecting basal systemic and renal hemodynamics. These data suggest a major role of AII in the development of early abnormalities in patients with HF.

The impact of early normalization of haematocrit by erythropoietin on renal damage in the remnant kidney model

BACKGROUND

Correction of anaemia in moderate to advanced renal failure is still a matter of debate because of postulated detrimental effects of erythropoietin on the progression of renal damage.

METHODS

The renal effects of early normalization of haematocrit (Htc) by erythropoietin (rHuEpo) were investigated from the time of 5/6 nephrectomy up to 8 weeks post-intervention in three groups of remnant kidney model rats: untreated controls (CON), rats receiving 100 UI/kg body-wt of rHuEpo i.p. twice a week (EPO), and rats receiving rHuEpo in which periodic phlebotomies maintained Htc similar to the value of the control group (PHL). The latter group was included to evaluate the direct effects of rHuEpo on renal damage, i.e. independent from Htc correction.

RESULTS

Two weeks after renal ablation (basal), Htc decreased in CON and PHL rats (from 49.3+/-1.4% to 43.2+/- 1.1, P < 0.05 and from 49.6+/-1.1 to 43.3+/-1.5%, P<0.05 respectively), while it remained consistently normal in EPO rats (48.9+/-1.2% to 48.9+/-1.50/%, P<0.05 vs other groups). Thereafter Htc did not change throughout the remaining period in all groups. At the end of the study, with respect to basal, resting blood pressure increased significantly by the same extent in CON (+ 13+/-2%) and EPO rats (+ 15+/-5%), while it remained constant in PHL rats. Notably, creatinine clearance significantly decreased in CON (-53+/-8% 8 vs basal) and EPO (-38+/-8% vs basal), while it did not change in PHL rats. Likewise the degree of proteinuria as well as renal morphologic alterations and glomerular hypertrophy/sclerosis was similar in CON and EPO rats, and was significantly more severe than in the phlebotomized group. The only difference detected between CON and EPO group was the greater mesangial hypercellularity in rHuEpo-treated rats.

CONCLUSION

In uraemic rats, chronic treatment with rHuEpo aimed at normalization of Htc beginning the early stage of renal failure does not inevitably account for a rise in systemic blood pressure. In addition, neither erythropoietin per se nor the correction of haematocrit accelerates the progression of renal damage when blood pressure remains constant.

Salt intake and renal outcome in patients with progressive renal disease

Experimental studies suggest that salt intake plays a critical role in the progressive glomerular filtration rate (GFR) loss of established renal disease; however, this issue has never been addressed in humans. To this aim, we have retrospectively analyzed the clinical data of patients with chronic renal failure (CRF), in whom a low-protein diet was prescribed, over a period of about 3 years. On the basis of the daily urinary sodium output, the patients were divided into two groups: a group of patients constantly ingesting > 200 mEq NaCl/day (high sodium intake, HSD, n = 30) and a group in which salt intake was < 100 mEq/day (low sodium intake, LSD, n = 27). Patients taking diuretics or ACE inhibitors were excluded. At baseline, the LSD group, as compared to the HSD group, was characterized by significantly lower creatinine clearance (24 +/- 2 vs. 28 +/- 2 ml/min) and higher proteinuria (2.9 +/- 0.3 vs. 1.5 +/- 0.2 g/day). Despite the presence of these risk factors for progression, and a similar control of blood pressure (the average of the mean arterial pressure during follow-up was 111 +/- 2 mm Hg in LSD and 107 +/- 2 mm Hg in HSD), the LSD patients showed a better renal outcome: in this group, as compared to HSD, the GFR decline was lower (0.25 +/- 0.07 vs. 0.51 +/- 0.09 ml/min/month, p < 0.05), and proteinuria did not change while it markedly increased in HSD. During follow-up, LSD patients also ingested a significantly lower amount of protein. This study therefore suggests that efficacious salt restriction in CRF patients improves the outcome of renal disease independent from its antihypertensive effects.

Enhancement of nitric oxide synthesis by L-arginine supplementation in renal disease: is it good or bad?

L-Arginine is a important component of our diet characterized by multiple physiological and pharmacological actions. In the last decade, this amino acid has attracted major interest since it has been identified as the natural substrate of nitric oxide, and is now recognized to play a major role in the regulation of vascular tone. This review, while summarizing the knowledge of the renal actions of the L-arginine/nitric oxide pathway in health and renal disease, focuses on the potential therapeutic implications of the increase in nitric oxide synthesis attained by L-arginine supplementation.

Physiologic role and diuretic efficacy of atrial natriuretic peptide in health and chronic renal disease

In recent years, different clinical studies have provided new information on the pathophysiological role and diuretic effectiveness of atrial natriuretic peptide (ANP) in subjects with normal renal function and patients with chronic renal disease. Plasma ANP (pANP) was increased by infusion at the lowest doses ever tested in humans who were on low salt diet to the levels that the same subjects gained when on a normal salt diet; ANP accounted for at least 40% of the increase of natriuresis. Similarly, ANP appeared to be mainly involved in the physiological down-regulation of salt excretion (that is, during the shift from a normal to low-sodium diet). Interestingly, data have been also attained on the efficacy of ANP as diuretic agent when administered at a low nonhypotensive dosage in normals as well as CRF patients. Indeed, low-dose ANP promoted a marked increase of sodium excretion in CRF patients to the same levels observed in normals, likely because the renal patients exhibited a more marked pANP increment secondary to the lower renal catabolism of the infused hormone. Moreover, aldosterone suppression was greater in CRF patients with respect to normals. Furthermore, the fractional urinary excretion of cGMP increased more in CRF patients than in normals. Finally, ANP infusion augmented the urinary losses of the main solutes retained in CRF (urea, potassium, phosphorous) with a significant decrease in the plasma levels. Hence, ANP per se not only plays a significant role in the up- and down-regulation of sodium excretion in healthy state and chronic renal disease, but it may also be considered to be a powerful and unique diuretic agent in CRF at nonhypotensive dosages.

Pathophysiological role and diuretic efficacy of atrial natriuretic peptide in renal patients

It has been suggested that renal disease is characterized by the presence of resistance to the natriuretic effects of atrial peptide (ANP). In this study, plasma ANP (pANP) and renal function were evaluated during stepwise infusion of low ANP doses (2, 4, 8, and 16 ng/kg per min) in glomerulonephritic patients with (CRF) or without (GN) moderate renal failure, and in normal subjects (NOR), kept at low-sodium diet (LSD; 35 mEq NaCl/day). To assess the physiological ANP levels, pANP was also measured in the three groups after normal-sodium diet (NSD; 235 mEq NaCl/day). ANP did not affect systemic and renal perfusion at any of the doses tested; a significant increment of GFR was observed only in NOR and GN. The 2-, 4-, and 8-ng/kg doses increased pANP to values overlapping the physiological concentrations measured at NSD; this was associated with a dose-dependent increment of urinary excretion of sodium (UNaV) that reached analogous levels in the three groups. ANP accounted for approximately 40% of the UNaV increment evoked by NSD in patients and in normal subjects. The 16-ng/kg dose led to supraphysiological levels that induced a similar marked enhancement of UNaV (from the basal value of 0.12 +/- 0.02 to 0.42 +/- 0.08 mEq/min in CRF, from 0.13 +/- 0.02 to 0.73 +/- 0.08 in GN, and from 0.09 +/- 0.02 to 0.49 +/- 0.11 in NOR). In CRF, the normal natriuretic response to the highest dose was caused by a larger increase of fractional UNaV that was strictly dependent on the greater pANP increment, as demonstrated by similar changes in the fractional excretion of cGMP, and, in part, on the greater aldosterone decrease. In all groups, ANP also induced a dose-dependent urinary loss of phosphate, potassium, and urea, resulting in a significant 15 to 25% decrease in the plasma levels. Thus, in GN and CRF patients, ANP plays a significant role in the renal handling of sodium; moreover, the achievement of low supraphysiological pANP levels leads to a conspicuous natriuresis associated with unique extranatriuretic effects.

Fetal proteins and chronic treatment with low-dose erythropoietin

The potential stimulating effect of erythropoietin on the production of fetal proteins (FPs) has not been explored in human subjects. Therefore, the plasma levels of fetal fibrinogen (FF), carcinoembriogenic antigen (CEA), alpha-fetoprotein (AFP), and fetal hemoglobin (HbF) were measured in 12 uremic hemodialyzed patients before the first administration and after 1, 2, and 3 months of low-dose erythropoietin (r-Hu-EPO; 45 U/kg body wt I.V., thrice weekly). Such a treatment efficaciously increased total hemoglobin (Hb). CEA and AFP increased from 5.8 +/- 1.1 ng/ml and 2.9 +/- 0.9 ng/ml to the final value of 43.2 +/- 3.9 ng/ml and 8.7 +/- 1.1 ng/ml, respectively, in the absence of detectable neoplastic diseases. The levels of FF did not change. HbF levels increased from <3% of Hb to the peak value of 48% at the end of the first month; subsequently, a progressive reduction in HbF was observed. Similar changes were detected in the reticulocyte count (RET). A striking correlation was found between HbF and RET (r = 0.8633, p < 0.0001), indicating that the increment in HbF was dependent on the erythroid activity. In conclusion, this study evidences broader than expected effects of erythropoietin on the synthesis of FP and suggests that (1) r-Hu-EPO markedly increases HbF in a condition of suppressed bone marrow activity, (2) the measurement of the cell proliferation markers CEA and AFP is unreliable during r-Hu-EPO therapy, and (3) the prothrombotic state associated with chronic r-Hu-EPO treatment in patients with uremia cannot be attributed to the presence of FF.

Does high salt intake cause hyperfiltration in patients with essential hypertension?

In animal models of salt-dependent hypertension, hyperfiltration is associated with a faster decline in renal function and there is evidence that in hypertensive man, increased creatinine clearance is a marker of early hypertensive nephropathy. We have studied the influence of salt intake on the glomerular filtration rate (GFR) (Creatinine Clearance) in 14 patients with mild hypertension. Each patient was studied in random order and according to a crossover design, at habitual salt intake, at high salt intake (ie habitual +50/100 mmol/day) and at low salt intake (habitual -50/100 mmol/day). Protein, calcium and potassium intake was fixed across the three study periods. The control group was formed by seven healthy subjects. High salt intake, caused a significant (P < 0.01) increase in 24 h mean arterial pressure (MAP) and the expected suppression in plasma renin activity (PRA) and in plasma aldosterone. Seven patients were classified as salt-sensitive. The GFR was significantly higher (P < 0.01) at high salt intake (125 +/- 10 ml/min) than at habitual (113 +/- 7 ml/min) and at low salt intake (97 +/- 6 ml/min). On aggregate urinary salt excretion was significantly related with the GFR (P < 0.01 by correlation analysis for repeated observations) and the slope of this relationship predicted that a 100 mmol/day increase in salt intake is associated with the 14.6 ml/min rise in the GFR. The relationship between GFR and 24 h urinary salt in salt sensitive patients did not differ from that in salt resistant patients. The GFR response to salt loading was largely independent of the renin-aldosterone system. No change in arterial pressure nor in GFR was observed in healthy subjects. At fixed protein intake, changes in salt intake in the physiological range are associated with important GFR variations in mild hypertensives. As long as hyperfiltration in mild hypertension is a predictor of renal function deterioration, high salt intake, independent of the effect of arterial pressure, could be a factor that contributes to nephronic obsolescence in patients with essential hypertension.