Low-Protein Diets in Diabetic Chronic Kidney Disease (CKD) Patients: Are They Feasible and Worth the Effort?

Low-protein diets (LPDs) are often considered as contraindicated in diabetic patients, and are seldom studied. The aim of this observational study was to provide new data on this issue. It involved 149 diabetic and 300 non-diabetic patients who followed a LPD, with a personalized approach aimed at moderate protein restriction (0.6 g/day). Survival analysis was performed according to Kaplan-Meier, and multivariate analysis with Cox model. Diabetic versus non-diabetic patients were of similar age (median 70 years) and creatinine levels at the start of the diet (2.78 mg/dL vs. 2.80 mg/dL). There was higher prevalence of nephrotic proteinuria in diabetic patients (27.52% vs. 13.67%, p = 0.002) as well as comorbidity (median Charlson index 8 vs. 6 p = 0.002). Patient survival was lower in diabetic patients, but differences levelled off considering only cases with Charlson index > 7, the only relevant covariate in Cox analysis. Dialysis-free survival was superimposable in the setting of good compliance (Mitch formula: 0.47 g/kg/day in both groups): about 50% of the cases remained dialysis-free 2 years after the first finding of e-GFR (estimated glomerular filtration rate) < 15 mL/min, and 1 year after reaching e-GFR < 10 mL/min. In patients with type 2 diabetes, higher proteinuria was associated with mortality and initiation of dialysis. In conclusion, moderately restricted LPDs allow similar results in diabetic and non non-diabetic patients with similar comorbidity.

Vegan-vegetarian low-protein supplemented diets in pregnant CKD patients: fifteen years of experience

BACKGROUND

Pregnancy in women with advanced CKD becoming increasingly common. However, experience with low-protein diets in CKD patients in pregnancy is still limited. Aim of this study is to review the results obtained over the last 15 years with moderately restricted low-protein diets in pregnant CKD women (combining: CKD stages 3-5, proteinuria: nephrotic at any time, or > =1 g/24 at start or referral; nephrotic in previous pregnancy). CKD patients on unrestricted diets were employed for comparison.

METHODS

STUDY PERIOD

January, 2000 to September, 2015: 36 on-diet pregnancies (31 singleton deliveries, 3 twin deliveries, 1 pregnancy termination, 1 miscarriage); 47 controls (42 singleton deliveries, 5 miscarriages). The diet is basically vegan; since occasional milk and yoghurt are allowed, we defined it vegan-vegetarian; protein intake (0.6-0.8 g/Kg/day), keto-acid supplementation, protein-unrestricted meals (1-3/week) are prescribed according to CKD stage and nutritional status. Statistical analysis was performed as implemented on SPSS.

RESULTS

Patients and controls were similar (p: ns) at baseline with regard to age (33 vs 33.5), referral week (7 vs 9), kidney function (CKD 3-5: 48.4 % vs 64.3 %); prevalence of hypertension (51.6 % vs 40.5 %) and proteinuria >3 g/24 h (16.1 % vs 12.2 %). There were more diabetic nephropathies in on-diet patients (on diet: 31.0 % vs controls 5.3 %; p 0.007 (Fisher)) while lupus nephropathies were non-significantly higher in controls (on diet: 10.3 % vs controls 23.7 %; p 0.28 (Fisher)). The incidence of preterm delivery was similar (<37 weeks: on-diet singletons 77.4 %; controls: 71.4 %). The incidence of other adverse pregnancy related outcomes was non-significantly lower in on-diet patients (early preterm delivery: on diet: 32.3 % vs controls 35.7 %; birth-weight = <1.500 g: on diet: 9.7 % vs controls 23.8 %). None of the singletons in the on-diet series died, while two perinatal deaths occurred among the controls (p = 0.505). The incidence of small for gestational age (SGA <10th centile) and/or extremely preterm babies (<28th week) was significantly lower in singletons from on-diet mothers than in controls (on diet: 12.9 % vs controls: 33.3 %; p: 0.04 (Fisher)).

CONCLUSION

Moderate protein restriction in the context of a vegan-vegetarian supplemented diet is confirmed as a safe option in the management of pregnant CKD patients.

International Multi-Specialty Delphi Survey: Identification of Diagnostic Criteria for Hepatic and Renal Cyst Infection

BACKGROUND

Cyst infection is one of the complications of autosomal dominant polycystic kidney disease and polycystic liver disease. The diagnosis is typically made on a mix of clinical, laboratory and imaging abnormalities but the importance of individual items is uncertain. We aimed to perform a Delphi survey amongst physicians to achieve consensus on diagnostic criteria.

METHODS

We retrieved diagnostic items from the literature and conducted physician and patient interviews. All items were combined to create the online questionnaire. Participants rated each item during 3 consecutive rounds. Items were rated for diagnostic helpfulness for hepatic and renal cyst infection on a 9-point scale with anchors, from extremely unimportant (n = 1) to extremely important (n = 9). We determined consensus with the disagreement index. The median rating of each item was calculated and categorized into inappropriate (≤3.4), uncertain (3.5-6.4) or appropriate (≥6.5). By combining all items that reached an appropriate consensus rating, we developed a diagnostic algorithm based on expert consensus.

RESULTS

We invited 58 physicians to participate in the survey. In total, 35 (60%) responded to round 1 of which 91% (n = 32) and 86% (n = 30) responded to round 2 and 3, respectively. The final panel included 23 nephrologists, 5 hepatologists, a nuclear medicine specialist and an infectious disease physician from 11 countries (male 67%, mean age 47 ± 11 years, median clinical experience 21 years). The panel rated the diagnostic helpfulness of 59 potential items. Ultimately, 22 hepatic and 26 renal items were rated appropriate, including positive blood cultures and fluorodeoxyglucose positron-emission CT imaging. Ultrasonography and absence of intracystic bleeding were amongst those deemed uncertain or inappropriate. Subsequently, by combining items rated appropriate, we developed a clinical tool to diagnose hepatic and renal cyst infection.

CONCLUSIONS

We identified diagnostic items for hepatic and renal cyst infection and developed an expert-based diagnostic algorithm, which may aid physicians in the diagnostic work-up. A prospective study is necessary to validate this algorithm.

Low-protein diets for chronic kidney disease patients: the Italian experience

BACKGROUND

Nutritional treatment has always represented a major feature of CKD management. Over the decades, the use of nutritional treatment in CKD patients has been marked by several goals. The first of these include the attainment of metabolic and fluid control together with the prevention and correction of signs, symptoms and complications of advanced CKD. The aim of this first stage is the prevention of malnutrition and a delay in the commencement of dialysis. Subsequently, nutritional manipulations have also been applied in association with other therapeutic interventions in an attempt to control several cardiovascular risk factors associated with CKD and to improve the patient's overall outcome. Over time and in reference to multiple aims, the modalities of nutritional treatment have been focused not only on protein intake but also on other nutrients.

DISCUSSION

This paper describes the pathophysiological basis and rationale of nutritional treatment in CKD and also provides a report on extensive experience in the field of renal diets in Italy, with special attention given to approaches in clinical practice and management. Italian nephrologists have a longstanding tradition in implementing low protein diets in the treatment of CKD patients, with the principle objective of alleviating uremic symptoms, improving nutritional status and also a possibility of slowing down the progression of CKD or delaying the start of dialysis. A renewed interest in this field is based on the aim of implementing a wider nutritional therapy other than only reducing the protein intake, paying careful attention to factors such as energy intake, the quality of proteins and phosphate and sodium intakes, making today's low-protein diet program much more ambitious than previous. The motivation was the reduction in progression of renal insufficiency through reduction of proteinuria, a better control of blood pressure values and also through correction of metabolic acidosis. One major goal of the flexible and innovative Italian approach to the low-protein diet in CKD patients is the improvement of patient adherence, a crucial factor in the successful implementation of a low-protein diet program.

Diabetic Kidney Disease: A Syndrome Rather Than a Single Disease

The term "diabetic kidney" has recently been proposed to encompass the various lesions, involving all kidney structures that characterize protean kidney damage in patients with diabetes. While glomerular diseases may follow the stepwise progression that was described several decades ago, the tenet that proteinuria identifies diabetic nephropathy is disputed today and should be limited to glomerular lesions. Improvements in glycemic control may have contributed to a decrease in the prevalence of glomerular lesions, initially described as hallmarks of diabetic nephropathy, and revealed other types of renal damage, mainly related to vasculature and interstitium, and these types usually present with little or no proteinuria. Whilst glomerular damage is the hallmark of microvascular lesions, ischemic nephropathies, renal infarction, and cholesterol emboli syndrome are the result of macrovascular involvement, and the presence of underlying renal damage sets the stage for acute infections and drug-induced kidney injuries. Impairment of the phagocytic response can cause severe and unusual forms of acute and chronic pyelonephritis. It is thus concluded that screening for albuminuria, which is useful for detecting "glomerular diabetic nephropathy", does not identify all potential nephropathies in diabetes patients. As diabetes is a risk factor for all forms of kidney disease, diagnosis in diabetic patients should include the same combination of biochemical, clinical, and imaging tests as employed in non-diabetic subjects, but with the specific consideration that chronic kidney disease (CKD) may develop more rapidly and severely in diabetic patients.

The "phosphorus pyramid": a visual tool for dietary phosphate management in dialysis and CKD patients

Phosphorus retention plays a pivotal role in the onset of mineral and bone disorders (MBD) in chronic kidney disease (CKD). Phosphorus retention commonly occurs as a result of net intestinal absorption exceeding renal excretion or dialysis removal. The dietary phosphorus load is crucial since the early stages of CKD, throughout the whole course of the disease, up to dialysis-dependent end-stage renal disease.Agreement exits regarding the need for dietary phosphate control, but it is quite challenging in the real-life setting. Effective strategies to control dietary phosphorus intake include restricting phosphorus-rich foods, preferring phosphorus sourced from plant origin, boiling as the preferred cooking procedure and avoiding foods with phosphorus-containing additives. Nutritional education is crucial in this regard.Based on the existing literature, we developed the "phosphorus pyramid", namely a novel, visual, user-friendly tool for the nutritional education of patients and health-care professionals. The pyramid consists of six levels in which foods are arranged on the basis of their phosphorus content, phosphorus to protein ratio and phosphorus bioavailability. Each has a colored edge (from green to red) that corresponds to recommended intake frequency, ranging from "unrestricted" to "avoid as much as possible".The aim of the phosphorus pyramid is to support dietary counseling in order to reduce the phosphorus load, a crucial aspect of integrated CKD-MBD management.

Vegan-vegetarian diets in pregnancy: danger or panacea? A systematic narrative review

BACKGROUND

Although vegan-vegetarian diets are increasingly popular, no recent systematic reviews on vegan-vegetarian diets in pregnancy exist.

OBJECTIVES

To review the literature on vegan-vegetarian diets and pregnancy outcomes.

SEARCH STRATEGY

PubMed, Embase, and the Cochrane library were searched from inception to September 2013 for pregnancy and vegan or vegetarian Medical Subject Headings (MeSH) and free-text terms.

SELECTION CRITERIA

Vegan or vegetarian diets in healthy pregnant women. We excluded case reports and papers analysing vegan-vegetarian diets in poverty and malnutrition. Searching, paper selection, and data extraction were performed in duplicate.

DATA COLLECTION AND ANALYSIS

The high heterogeneity of the studies led to a narrative review.

MAIN RESULTS

We obtained 262 full texts from 2329 references; 22 selected papers reporting maternal-fetal outcomes (13) and dietary deficiencies (nine) met the inclusion criteria. None of the studies reported an increase in severe adverse outcomes or in major malformations, except one report of increased hypospadias in infants of vegetarian mothers. Five studies reported vegetarian mothers had lower birthweight babies, yet two studies reported higher birthweights. The duration of pregnancy was available in six studies and was similar between vegan-vegetarians and omnivores. The nine heterogeneous studies on microelements and vitamins suggest vegan-vegetarian women may be at risk of vitamin B12 and iron deficiencies.

AUTHOR'S CONCLUSIONS

The evidence on vegan-vegetarian diets in pregnancy is heterogeneous and scant. The lack of randomised studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan-vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirements.

Renal infarction versus pyelonephritis in a woman presenting with fever and flank pain

Patients with fever, flank pain, and dysuria frequently are encountered in the emergency department. Acute pyelonephritis is the most likely diagnosis; however, its clinical and radiologic presentation consistently overlap with that of acute renal infarction. Ultrasound is unable to distinguish early infarction from nonabscessed acute pyelonephritis. Hence, computed tomography or magnetic resonance imaging are needed. We report the case of a 68-year-old woman who presented with fever, flank pain, and dysuria, along with respiratory distress and tachycardia. Elevated values for inflammatory indexes suggested a diagnosis of acute pyelonephritis, and subsequent contrast-enhanced computed tomography showed hypodense wedge-shaped areas in both kidneys. However, the presence of a thin rim of capsular enhancement (cortical rim sign), the absence of perirenal inflammatory changes, and the location of the lesions apart from defined calyces suggested the alternative diagnosis of renal infarction. The underlying cause was not identified until an episode of acute dyspnea revealed paroxysmal arrhythmia. Our case demonstrates that a thorough knowledge of the imaging findings of renal infarction and acute pyelonephritis is essential to correctly making the diagnosis.

Association of low-protein supplemented diets with fetal growth in pregnant women with CKD

BACKGROUND AND OBJECTIVES

Women affected by CKD increasingly choose to get pregnant. Experience with low-protein diets is limited. The aim of this study was to review results obtained from pregnant women with CKD on supplemented vegan-vegetarian low-protein diets.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a single-arm, open intervention study between 2000-2012 of a low-protein diet in pregnant patients with stages 3-5 CKD or severe proteinuria (>1 g/d in the first trimester or nephrotic at any time). Stages 3-5 CKD patients who were not on low-protein diets for clinical, psychologic, or logistic reasons served as controls. The setting was the Obstetrics-Nephrology Unit dedicated to kidney diseases in pregnancy. The treated group included 24 pregnancies--21 singleton deliveries, 1 twin pregnancy, 1 abortion, and 1 miscarriage. Additionally, there were 21 controls (16 singleton deliveries, 5 miscarriages). The diet was a vegan-vegetarian low-protein diet (0.6-0.8 g/kg per day) with keto-acid supplementation and 1-3 protein-unrestricted meals allowed per week.

RESULTS

Treated patients and controls were comparable at baseline for median age (35 versus 34 years), referral week (7 versus 8), eGFR (59 versus 54 ml/min), and hypertension (43.5% versus 33.3%); median proteinuria was higher in patients on the low-protein diet (1.96 [0.1-6.3] versus 0.3 [0.1-2.0] g/d; P<0.001). No significant differences were observed in singletons with regard to gestational week (34 versus 36) or Caesarean sections (76.2% versus 50%). Kidney function at delivery was not different, but proteinuria was higher in the diet group. Incidence of small for gestational age babies was significantly lower in the diet group (3/21) versus controls (7/16; chi-squared test; P=0.05). Throughout follow-up (6 months to 10 years), hospitalization rates and prevalence of children below the third percentile were similar in both groups.

CONCLUSION

Vegan-vegetarian supplemented low-protein diets in pregnant women with stages 3-5 CKD may reduce the likelihood of small for gestational age babies without detrimental effects on kidney function or proteinuria in the mother.

Which low-protein diet for which CKD patient? An observational, personalized approach

OBJECTIVES

Low protein diets (LPDs) are milestones in chronic kidney disease (CKD). Concerns over compliance and safety limit their use. The aim of this study was to test the feasibility and main results of a multiple-choice approach to LPDs, adapted to patient preferences.

METHODS

From December 2007 to January 2013, all CKD patients (stages 4/5; progressive stage 3) without contraindications (malnutrition, short life expectancy), were offered two main LPDs (proteins 0.6 g/kg daily): Vegan supplemented (LPD-KA) or with "aproteic" commercial food (LPD-ACF). LPDs followed a qualitative approach based on forbidden and allowed food; one to three free meals per week, and flexible control policy (1-3 mo). Start of dialysis, death, and combined outcome (death-dialysis) were analyzed by Kaplan-Meier curves and Cox model. Comparison with dialysis in patients with glomerular filtration rate (GRF) <15 mL/min, (corresponding to "early" dialysis start) employed standardized mortality rates, with respect to the Italian and the United States Dialysis Registry.

RESULTS

One hundred eighty-five patients (222 patient-years) started at least a trial of LPD-KA, 122 (177 patients-years) LPD-ACF; only 3 patients with GFR <30 mL/min denied an LPD trial. Patients who chose LPD-KA were younger than those on LPD-ACF (63 versus 74 y), had less comorbidity (82% versus 93%), higher proteinuria (1.4 versus 0.7 g/d) and lower GFR (17 versus 23 mL/min) (P < 0.001). Median daily protein intake was 0.7 g/kg on both diets (Maroni-Mitch formula). The combined outcome (death or dialysis) was not influenced by the diet chosen (Cox analysis). Relative risk for death on the diet (patients with GFR <15 mL/min) was 0.5 with respect to the Italian Registry and 0.3 to the United States Dialysis Registry. The diets had comparable costs (1 y on dialysis: 50 patient-years on LPD).

CONCLUSIONS

The choice of diet is strictly linked to patient characteristics, thus supporting a multiple-choice offer. Once corrected for baseline data, both LPDs led to similar results, suggesting at least survival equivalence with dialysis, at lesser cost.

MYH9-related disease: a novel prognostic model to predict the clinical evolution of the disease based on genotype-phenotype correlations

MYH9-related disease (MYH9-RD) is a rare autosomal-dominant disorder caused by mutations in the gene for nonmuscle myosin heavy chain IIA (NMMHC-IIA). MYH9-RD is characterized by a considerable variability in clinical evolution: patients present at birth with only thrombocytopenia, but some of them subsequently develop sensorineural deafness, cataract, and/or nephropathy often leading to end-stage renal disease (ESRD). We searched for genotype-phenotype correlations in the largest series of consecutive MYH9-RD patients collected so far (255 cases from 121 families). Association of genotypes with noncongenital features was assessed by a generalized linear regression model. The analysis defined disease evolution associated to seven different MYH9 genotypes that are responsible for 85% of MYH9-RD cases. Mutations hitting residue R702 demonstrated a complete penetrance for early-onset ESRD and deafness. The p.D1424H substitution associated with high risk of developing all the noncongenital manifestations of disease. Mutations hitting a distinct hydrophobic seam in the NMMHC-IIA head domain or substitutions at R1165 associated with high risk of deafness but low risk of nephropathy or cataract. Patients with p.E1841K, p.D1424N, and C-terminal deletions had low risk of noncongenital defects. These findings are essential to patients' clinical management and genetic counseling and are discussed in view of molecular pathogenesis of MYH9-RD.

Vegetarian low-protein diets supplemented with keto analogues: a niche for the few or an option for many?

BACKGROUND

Low-protein diets are often mentioned but seldom used to slow chronic kidney disease (CKD) progression. The aim of the study was to investigate the potential for implementation of a simplified low-protein diet supplemented with alpha-keto analogues (LPD-KA) as part of the routine work-up in CKD patients.

METHODS

In an implementation study (December 2007-November 2011), all patients with CKD Stages IV-V not on dialysis, rapidly progressive Stage III and/or refractory proteinuria, were offered either a simplified LPD-KA, or commercially available low-protein food. LPD-KA consisted of proteins 0.6 g/kg/day, supplementation with Ketosteril 1 pill/10 Kg, 1-3 free-choice meals/week and a simplified schema based on 'allowed' and 'forbidden' foods. 'Success' was defined as at least 6 months on LPD-KA. Progression was defined as reduction in glomerular filtration rate (GFR)[(Chronic Kidney Disease Epidemiology Collaboration) formula CKD-EPI] in patients with at least 6 months of follow-up.

RESULTS

Of about 2500 patients referred (8% CKD Stages IV-V), 139 started LPD-KA; median age (70 years) and prevalence of comorbidity (79%) were in line with the dialysis population. Start of dialysis was the main reason for discontinuation (40 cases, unplanned in 7); clinical reasons were recorded in 7, personal preference in 14 and improvement and death in 8 each. The low gross mortality (4% per year) and the progression rate (from -8 to 0 mL/min/year at 6 months) are reassuring concerning safety. None of the baseline conditions, including age, educational level, comorbidity or kidney function, discriminated the patients who followed the diet for at least 6 months.

CONCLUSIONS

Our data suggest a wider offer of LPD-KA to patients with severe and progressive CKD. The promising results in terms of mortality and progression need confirmation with different study designs.

Severe diabetic nephropathy in type 1 diabetes and pregnancy--a case series

BACKGROUND

Diabetes and nephropathy are important challenges during pregnancy, increasingly encountered because of the advances in maternal-fetal care.

AIM

To evaluate the maternal and fetal outcomes recorded in "severe" diabetic nephropathy in type 1 diabetic patients referred to nephrological healtcare.

METHODS

The study was performed in an outpatient unit dedicated to kidney diseases in pregnancy (with joint nephrological and obstetric follow-up and strict cooperation with the diabetes unit). 383 pregnancies were referred to the outpatient unit in 2000-2012, 14 of which were complicated by type 1 diabetes. The report includes 12 deliveries, including 2 pregnancies in 1 patient; one twin pregnancy; 2 spontaneous abortions were not included. All cases had long-standing type 1 diabetes (median of 21 (15-31) years), relatively high median age (35 (29-40) years) and end-organ damage (all patients presented laser-treated retinopathy and half of them clinical neuropathy). Median glomerular filtration rate (GFR) at referral was 67 ml/min (48-122.6), proteinuria was 1.6 g/day (0.1-6.3 g/day).

RESULTS

Proteinuria steeply increased in 11/12 patients, reaching the nephrotic range in nine (6 above 5 g/day). One patient increased by 2 chronic kidney disease (CKD) stages. Support therapy included blood pressure and diabetes control, bed rest, and moderate protein restriction. All children were preterm (7 early preterm); early spontaneous labor occurred in 4/12 patients. All singletons were appropriate for gestational age and developed normally after birth. The male twin child died 6 days after birth (after surgery for great vessel transposition).

CONCLUSIONS

Diabetic patients with severe diabetic nephropathy are still present a considerable challenge. Therefore, further investigations are required, particularly on proteinuria management and the occurrence of spontaneous labor.