Assessment of Proteinuria in Patients with Chronic Kidney Disease Stage 3: Albuminuria and Non-Albumin Proteinuria

Background and Objective

Proteinuria assessment is key in investigating chronic kidney disease (CKD) but uncertainty exists regarding optimal methods. Albuminuria, reflecting glomerular damage, is usually measured, but non-albumin proteinuria (NAP), reflecting tubular damage, may be important. This study investigated the prevalence and associations of albuminuria and NAP, and the optimum number of urine specimens required.

Methods

1,741 patients with CKD stage 3, recruited from primary care, underwent medical history, clinical assessment, blood sampling, and submitted three early morning urine samples for albumin to creatinine ratio (uACR) and protein to creatinine ratios (uPCR). Albuminuria was defined as uACR ≥3 mg/mmol in at least two of three samples. Isolated NAP was defined as uPCR ≥17 mg/mmol in two of three samples and uACR <3 mg/mmol in all three. Prevalence and associations of albuminuria and NAP, degree of agreement between single uACR and average of three uACRs, and urine albumin to protein ratio (uAPR = uACR/uPCR) were identified.

Results

Albuminuria prevalence was 16% and NAP 6%. Using a <1 mg/mmol threshold for uACR reduced NAP prevalence to 3.6%. Independent associations of albuminuria were: males (OR 3.06 (95% CI, 2.23–4.19)), diabetes (OR 2.14 (1.53–3.00)), lower estimated glomerular filtration rate ((OR 2.06 (1.48–2.85) 30–44 vs 45–59), and high sensitivity CRP ((OR 1.70 (1.25–2.32)). NAP was independently associated with females (OR 6.79 (3.48–13.26)), age (OR 1.62 (1.02–2.56) 80 s vs 70–79) and high sensitivity CRP ((OR 1.74 (1.14–2.66)). Of those with uPCR≥17 mg/mmol, 62% had uAPR<0.4. Sensitivity of single uACR was 95%, specificity 98%, PPV 90%. Bland Altman plot one vs average of three uACRs showed: mean difference 0.0064 mg/mmol (SD 4.69, limits of agreement −9.19 to +9.20, absolute mean difference 0.837).

Conclusions

In CKD stage 3, albuminuria has associations distinct from those of isolated NAP (except for inflammatory markers). Single uACR categorised albuminuria but average of three performed better for quantification.     

Role of the kidney in the metabolism of apolipoprotein A-IV: influence of the type of proteinuria

Increased plasma concentrations of apolipoprotein A-IV (apoA-IV) in chronic renal disease suggest a metabolic role of the kidney for this antiatherogenic protein. Therefore, we investigated patients with various forms of proteinuria and found increased serum concentrations of apoA-IV in 124 nephrotic patients compared with 274 controls (mean 21.9 +/- 9.6 vs. 14.4 +/- 4.0 mg/dl; P < 0.001). Decreasing creatinine clearance showed a strong association with increasing apoA-IV levels. However, serum albumin levels significantly modulated apoA-IV levels in patients with low creatinine clearance, resulting in lower levels of apoA-IV in patients with low compared with high albumin levels (21.4 +/- 8.6 vs. 29.2 +/- 8.4 mg/dl; P = 0.0007). Furthermore, we investigated urinary apoA-IV levels in an additional 66 patients with a wide variety of proteinuria and 30 controls. Especially patients with a tubular type of proteinuria had significantly higher amounts of apoA-IV in urine than those with a pure glomerular type of proteinuria and controls (median 45, 14, and 0.6 ng/mg creatinine, respectively). We confirmed these results in affected members of a family with Dent's disease, who are characterized by an inherited protein reabsorption defect of the proximal tubular system. In summary, our data demonstrate that the increase of apoA-IV caused by renal impairment is significantly modulated by low levels of serum albumin as a measure for the severity of the nephrotic syndrome. From this investigation of apoA-IV in urine as well as earlier immunohistochemical studies, we conclude that apoA-IV is filtered through the normal glomerulus and is subsequently reabsorbed mainly by proximal tubular cells.     

Cyclosporin treatment of IgA nephropathy: a short term controlled trial.

Cyclosporin''s known regulatory effects on the immune system suggest that it may be useful in treating patients with IgA nephropathy. A randomised prospective single blind study of 19 patients with IgA nephropathy and proteinuria (greater than 1.5 g/day) was conducted to determine the therapeutic value of cyclosporin. The patients were divided into two groups: nine patients were given oral cyclosporin (5 mg/kg/day) for 12 weeks and 10 patients a placebo. The two groups were comparable in age of presentation, ratio of men to women, plasma creatinine and serum IgA concentrations, creatinine clearance, daily urinary protein excretion, severity of renal histopathological changes, and prevalence of hypertension. A significant reduction of proteinuria and an increase of plasma albumin concentration was observed with treatment with cyclosporin. Nevertheless, a significant rise of plasma creatinine concentration and a fall in creatinine clearance was found in patients after six weeks'' treatment with cyclosporin, although the plasma cyclosporin concentrations were maintained within a narrow therapeutic range. Serum IgA concentrations were reduced in seven patients. Renal function improved within eight weeks after treatment was stopped. Three months after treatment was stopped proteinuria remained less than half of the pretreatment values in three patients. No similar biochemical changes were observed in the controls. Short term cyclosporin therapy may be beneficial in reducing proteinuria in some patients with IgA nephropathy. As transient renal impairment was seen, despite cyclosporin concentrations being maintained within a narrow therapeutic range, indiscriminate use of cyclosporin in glomerulonephritis should be discouraged.     

Protein creatinine index and Albustix in assessment of proteinuria.

The protein creatinine index in early morning and random urine specimens was compared with the 24 hour urinary excretion of protein in normal subjects and outpatients with abnormal proteinuria. A protein creatinine index (defined as (mg protein/1 divided by creatinine mmol/1) times 10) below 125 in a random specimen excluded abnormal proteinuria, whereas an index of more than 136 indicated the presence of pathological proteinuria. The index for random specimens provided a useful semiquantitative assessment of the 24 hour excretion of protein (mg protein/24 hours), but the index for early morning specimens was less reliable. Errors with Albustix were partly due to intra and inter observer variations in the interpretation of the colour formed when compared with the chart provided. It is proposed that the protein creatinine index on random urine samples should be used to supplement dipsticks in screening for proteinuria in cases where misclassification would be serious.     

Cross sectional longitudinal study of spot morning urine protein:creatinine ratio, 24 hour urine protein excretion rate,glomerular filtration rate,and end stage renal failure in chronic renal disease in patients without diabetes.

OBJECTIVE: To evaluate whether the protein:creatinine ratio in spot morning urine samples is a reliable indicator of 24 hour urinary protein excretion and predicts the rate of decline of glomerular filtration rate and progression to end stage renal failure in non-diabetic patients with chronic nephropathy. DESIGN: Cross sectional correlation between the ratio and urinary protein excretion rate. Univariate and multivariate analysis of baseline predictors, including the ratio and 24 hour urinary protein, of decline in glomerular filtration rate and end stage renal failure in the long term. SETTING: Research centre in Italy. SUBJECTS: 177 non-diabetic outpatients with chronic renal disease screened for participation in the ramipril efficacy in nephropathy study. MAIN OUTCOME MEASURES: Rate of decline in filtration rate evaluated by repeated measurements of unlabelled iohexol plasma clearance and rate of progression to renal failure. RESULTS: Protein:creatinine ratio was significantly correlated with absolute and log transformed 24 hour urinary protein values (P = 0.0001 and P < 0.0001, respectively.) Ratios also had high predictive value for rate of decline of the glomerular filtration rate (univariate P = 0.0003, multivariate P = 0.004) and end stage renal failure (P = 0.002 and P = 0.04). Baseline protein:creatinine ratios and rate of decline of the glomerular filtration rate were also significantly correlated (P < 0.0005). In the lowest third of the protein:creatinine ratio (< 1.7) there was 3% renal failure compared with 21.2% in the highest third (> 2.7) (P < 0.05). CONCLUSIONS: Protein:creatinine ratio in spot morning urine samples is a precise indicator of proteinuria and a reliable predictor of progression of disease in non-diabetic patients with chronic nephropathies and represents a simple and inexpensive procedure in establishing severity of renal disease and prognosis.     

Comparison of enalapril and nifedipine in treating non-insulin dependent diabetes associated with hypertension: one year analysis.

OBJECTIVES--To compare the efficacy, safety, and tolerance of enalapril and nifedipine in hypertensive patients with non-insulin dependent diabetes. DESIGN--One year double blind follow up of patients randomly allocated to either enalapril or nifedipine with matching placebos for the alternative drug. SETTING--Metabolic Investigation Unit, Hong Kong. SUBJECTS--102 patients were randomised: 52 to nifedipine and 50 to enalapril. At baseline 44 patients had normoalbuminuria, 36 microalbuminuria, and 22 macroalbuminuria. MAIN OUTCOME MEASURES--Blood pressure, albuminuria, and parameters of renal function and glycaemic control. RESULTS--In patients who completed one year''s treatment the median dose required by the nifedipine group (n = 49) was 60 mg/day; seven (14%) required additional diuretics. Of 41 patients given enalapril, 37 required the maximum dose (40 mg/day) and 27 (76%) required diuretics. At one year mean arterial blood pressures were similar in both groups. Albuminuria fell by 54% in the enalapril group and 11% in the nifedipine group (p = 0.006). Fractional albumin clearance ratio fell by 47% in the enalapril group and increased by 3% in the nifedipine group (p = 0.009). Creatinine clearance fell similarly in both groups but plasma creatinine concentration was increased by 20% in the enalapril group versus 8% in the nifedipine group (p = 0.001). CONCLUSION--Patients taking enalapril often required diuretics to control blood pressure. Enalapril reduced proteinuria significantly more than nifedipine in the microalbuminuric and macroalbuminuric patients but increased plasma creatinine concentrations. Longer follow up is required to clarify the importance of enalapril''s antiproteinuric effect.     

Laboratory measurement of urine albumin and urine total protein in screening for proteinuria in chronic kidney disease

Laboratory measurement of urine total protein has been important for the diagnosis and monitoring of renal disease for decades, and since the late 1990s, urine albumin has been measured to determine whether a diabetic patient has incipient nephropathy. Evolving understanding of chronic kidney disease (CKD) and, in particular, the cardiovascular risks that CKD confers, demands more sensitive detection of protein in urine. As well, evidence is now emerging that cardiovascular and all-cause mortality risks are increased at levels within the current 'normal' range for urine albumin. Standardisation is essential to permit valid application of universal decision points, and a National Kidney Disease Education Program/International Federation of Clinical Chemistry and Laboratory Medicine (NKDEP/IFCC) Working Party is making progress towards a reference system for urine albumin. In the meantime, available data suggest that Australasian laboratory performance is adequate in terms of precision and accuracy above current decision limits for urine albumin. In contrast, the complexity of proteins in urine makes standardisation of urine total protein measurement impossible. As well, urine total protein measurement is insufficiently sensitive to detect clinically important concentrations of urine albumin. An Australasian Expert Group, the Proteinuria Albuminuria Working Group (PAWG) has proposed that urine albumin/creatinine ratio is measured in a fresh, first morning, spot sample to screen for proteinuria in CKD. Both NKDEP/IFCC and PAWG emphasise the need for standardisation of sample collection and handling.     

Role of glycaemic control in development of microalbuminuria in patients with insulin dependent diabetes.

OBJECTIVE--To ascertain which factors determine the progression from very low rates of albumin excretion to persistent microalbuminuria in patients with insulin dependent diabetes mellitus. DESIGN--A 10 year prospective study of a cohort of diabetic patients. SETTING--Outpatient department of the Portsmouth District Hospitals. SUBJECTS--97 patients with insulin dependent diabetes mellitus who were initially free of microalbuminuria and hypertension. MAIN OUTCOME MEASURE--Urinary albumin: creatinine ratio. RESULTS--Eight of the 97 patients had developed microalbuminuria (urinary albumin:creatinine ratio > 3 mg/mmol in three consecutive early morning samples) by the 10 year follow up. The group who developed microalbuminuria had higher baseline log10 plasma glucose concentrations (mean (SD), 1.210 (0.122) v 0.984 (0.196) mmol/l, P < 0.001) and glycated haemoglobin concentrations (1.112% (0.069%) v 0.997% (0.076%), P < 0.001) and a younger age at onset of diabetes (10.0 (5.5) v 15.6 (7.8) years, P < 0.05). There was no difference in baseline duration of diabetes, smoking, sex, insulin dose, body mass index, serum creatinine concentration, or systolic, diastolic, or mean arterial blood pressure between the two groups. Multiple linear regression analysis showed that urinary albumin:creatinine ratio at 10 years was influenced by initial albumin:creatinine ratio (P = 0.006), initial glycated haemoglobin concentration (P = 0.002), and duration of diabetes (P = 0.045). Genotype for angiotensin converting enzyme was not related to the development of microalbuminuria nor, in a larger group of patients, the presence of any degree of diabetic nephropathy. CONCLUSION--In patients with insulin dependent diabetes mellitus the progression of minimal albuminuria and the development of microalbuminuria is determined primarily by poor long term glycaemic control. There is a weaker relation with longer duration of disease and younger age at onset of diabetes, but blood pressure does not seem to be implicated. Gene polymorphism for angiotensin converting enzyme is not linked to the development of microalbuminuria or established diabetic nephropathy.     

Wilm's Tumor-1 Protein Levels in Urinary Exosomes from Diabetic Patients with or without Proteinuria

Background

Podocyte injury is an early feature of diabetic nephropathy (DN). Recently, urinary exosomal Wilm''s tumor-1 protein (WT1), shed by renal epithelial cells, has been proposed as a novel biomarker for podocyte injury. However, its usefulness as biomarker for early diabetic nephropathy has not been verified yet. We investigated urinary exosomal WT1 in type-1 diabetic patients to confirm its role as a non-invasive biomarker for predicting early renal function decline.

Methods

The expression of WT1 protein in urinary exosomes from spot urine samples of type-1 diabetes mellitus patients (n = 48) and healthy controls (n = 25) were analyzed. Patients were divided based on their urinary albumin excretion, ACR (mg/g creatinine) into non- proteinuria group (ACR<30 mg/g, n = 30) and proteinuria group (ACR>30 mg/g, n = 18). Regression analysis was used to assess the association between urinary exosomal levels of WT1 with parameters for renal function. Receiver Operating Characteristic (ROC) curve analysis was used to determine the diagnostic performance of exosomal WT-1.

Results

WT1 protein was detected in 33 out of 48 diabetic patients and in only 1 healthy control. The levels of urinary exosomal WT1 protein is significantly higher (p = 0.001) in patients with proteinuria than in those without proteinuria. In addition, all the patients with proteinuria but only half of the patients without proteinuria were positive for exosomal WT1. We found that the level of exosomal WT1 were associated with a significant increase in urine protein-to-creatinine ratio, albumin-to-creatinine ratio, and serum creatinine as well as a decline in eGFR. Furthermore, patients exhibiting WT1-positive urinary exosomes had decreased renal function compared to WT1-negative patients. ROC analysis shows that WT-1 effectively predict GFR<60 ml. min-1/1.73 m².

Conclusion

The predominant presence of WT1 protein in urinary exosomes of diabetic patients and increase in its expression level with decline in renal function suggest that it could be useful as early non-invasive marker for diabetic nephropathy.     

Diagnostic Accuracy of Urine Protein/Creatinine Ratio Is Influenced by Urine Concentration

Background

The usage of urine protein/creatinine ratio to estimate daily urine protein excretion is prevalent, but relatively little attention has been paid to the influence of urine concentration and its impact on test accuracy. We took advantage of 24-hour urine collection to examine both urine protein/creatinine ratio (UPCR) and daily urine protein excretion, with the latter as the reference standard. Specific gravity from a concomitant urinalysis of the same urine sample was used to indicate the urine concentration.

Methods

During 2010 to 2014, there were 540 adequately collected 24h urine samples with protein concentration, creatinine concentration, total volume, and a concomitant urinalysis of the same sample. Variables associated with an accurate UPCR estimation were determined by multivariate linear regression analysis. Receiver operating characteristic (ROC) curves were generated to determine the discriminant cut-off values of urine creatinine concentration for predicting an accurate UPCR estimation in either dilute or concentrated urine samples.

Results

Our findings indicated that for dilute urine, as indicated by a low urine specific gravity, UPCR is more likely to overestimate the actual daily urine protein excretion. On the contrary, UPCR of concentrated urine is more likely to result in an underestimation. By ROC curve analysis, the best cut-off value of urine creatinine concentration for predicting overestimation by UPCR of dilute urine (specific gravity ≦ 1.005) was ≦ 38.8 mg/dL, whereas the best cut-off values of urine creatinine for predicting underestimation by UPCR of thick urine were ≧ 63.6 mg/dL (specific gravity ≧ 1.015), ≧ 62.1 mg/dL (specific gravity ≧ 1.020), ≧ 61.5 mg/dL (specific gravity ≧ 1.025), respectively. We also compared distribution patterns of urine creatinine concentration of 24h urine cohort with a concurrent spot urine cohort and found that the underestimation might be more profound in single voided samples.

Conclusions

The UPCR in samples with low or high specific gravity is more likely to overestimate or underestimate actual daily urine protein amount, respectively, especially in a dilute urine sample with its creatinine below 38.8 mg/dL or a concentrated sample with its creatinine above 61.5 mg/dL. In particular, UPCR results should be interpreted with caution in cases that involve dilute urine samples because its overestimation may lead to an erroneous diagnosis of proteinuric renal disease or an incorrect staging of chronic kidney disease.     

Enalapril in subantihypertensive dosage attenuates kidney proliferation and functional recovery in normotensive ablation nephropathy of the rat

Most studies on the antiproliferative action of angiotensin converting enzyme inhibitors (ACEI) were performed in a rat hypertensive remnant kidney model with 5/6 kidney ablation which raised objections about the antihypertensive effect of ACEI and the influence of other antihypertensive drugs administered to remnant kidney control rats. To prevent these objections, a normotensive 4/6 remnant kidney model was elaborated and a subantihypertensive dosage of enalapril was used to evaluate its antiproliferative action. Subtotally nephrectomized rats (Nx) markedly increased the remnant kidney weight during a 4-week period and this rise was prevented by the treatment with enalapril (NxE) (Nx +297+/-35 mg vs. sham-operated +145+/-32 mg, p<0.001; NxE +154+/-35 mg vs. Nx p<0.001). While collagen concentration in the kidney cortex was not increased in sham-operated rats (Sham) in comparison with the control group (Ctrl) at the beginning of the study, the subsequent increase was significant in the Nx group and enalapril did not attenuate this increase (Sham 148+/-5 mg/100 g w.w. vs. Nx 164+/-2 mg/100 g w.w., p<0.01; NxE 161+/-4 mg/100 g w.w. vs. Sham p<0.05). The tubular protein/DNA ratio increase, which was significant in the Nx group, was inhibited by enalapril (Nx 26.2+/-10.5 vs. NxE 15.3+/-2.6, p<0.05). The protein/DNA ratio was much lower in glomeruli, with no significant changes in either the Nx or NxE groups. Serum urea concentrations were slightly higher in the Nx group than in the sham-operated group, but markedly elevated in the NxE group (Nx 10.71+/-0.76 mmol/l vs. Sham 6.10+/-0.33 mmol/l, p<0.001; NxE 28.9+/-2.6 mmol/l vs. Sham p<0.001). Creatinine concentrations in the Nx group were increased in comparison with the sham-operated group and markedly increased in the NxE group (Nx 63.7+/-3.56 micromol/l vs. Sham 37.2+/-2.84 micromol/l, p<0.001; NxE 107.0+/-5.2 micromol/l vs. Sham p<0.001). The clearance of creatinine was lower in the Nx group than in the sham-operated group and was markedly reduced in the NxE group (Nx 0.89+/-0.06 ml/min.g kidney wt. vs. Sham 1.05+/-0.16 ml/min x g kidney wt., p<0.01; NxE 0.58+/-0.029 ml/min x g kidney wt. vs. Sham, p<0.001). Enalapril improved proteinuria in comparison with the Nx group (NxE 5.6+/-0.6 mg/24 h vs. Nx 16.1+/-3.4 mg/24 h, p<0.05). Thus remnant kidney proliferation is substantial even in normotensive rats. It includes both proliferation and collagen accumulation with partial recovery of kidney weight and function, but is accompanied by enhanced proteinuria. Enalapril attenuates the proliferation and decreases proteinuria but prolongs kidney function recovery.     

The relationship between proteinuria and coronary risk: a systematic review and meta-analysis

Background

Markers of kidney dysfunction such as proteinuria or albuminuria have been reported to be associated with coronary heart disease, but the consistency and strength of any such relationship has not been clearly defined. This lack of clarity has led to great uncertainty as to how proteinuria should be treated in the assessment and management of cardiovascular risk. We therefore undertook a systematic review of published cohort studies aiming to provide a reliable estimate of the strength of association between proteinuria and coronary heart disease.

Methods and Findings

A meta-analysis of cohort studies was conducted to obtain a summary estimate of the association between measures of proteinuria and coronary risk. MEDLINE and EMBASE were searched for studies reporting an age- or multivariate-adjusted estimate and standard error of the association between proteinuria and coronary heart disease. Studies were excluded if the majority of the study population had known glomerular disease or were the recipients of renal transplants. Two independent researchers extracted the estimates of association between proteinuria (total urinary protein >300 mg/d), microalbuminuria (urinary albumin 30–300 mg/d), macroalbuminuria (urinary albumin >300 mg/d), and risk of coronary disease from individual studies. These estimates were combined using a random-effects model. Sensitivity analyses were conducted to examine possible sources of heterogeneity in effect size. A total of 26 cohort studies were identified involving 169,949 individuals and 7,117 coronary events (27% fatal). The presence of proteinuria was associated with an approximate 50% increase in coronary risk (risk ratio 1.47, 95% confidence interval [CI] 1.23–1.74) after adjustment for known risk factors. For albuminuria, there was evidence of a dose–response relationship: individuals with microalbuminuria were at 50% greater risk of coronary heart disease (risk ratio 1.47, 95% CI 1.30–1.66) than those without; in those with macroalbuminuria the risk was more than doubled (risk ratio 2.17, 1.87–2.52). Sensitivity analysis indicated no important differences in prespecified subgroups.

Conclusion

These data confirm a strong and continuous association between proteinuria and subsequent risk of coronary heart disease, and suggest that proteinuria should be incorporated into the assessment of an individual''s cardiovascular risk.     

A two-step screening, measurement of HbA1c in association with FPG, may be useful in predicting diabetes

Backgrounds

We compared the usefulness of fasting plasma glucose (FPG), or hemoglobin A1c (HbA1c), or both in predicting type 2 diabetes.

Methods

This retrospective cohort study investigated 9,322 Japanese adults (4,786 men and 4,536 women), aged 19–69 yrs, free of diabetes at baseline. Usefulness was assessed by predictive values (PV), sensitivity, specificity, and the area under the receiver operating characteristic curve (AUROC) maximised under the best cut-off point.

Results

During the average 6 years of follow-up, 221 men (4.6%) and 92 women (2%) developed diabetes. The best cut-off points for FPG (i.e., 5.67 mmol/l for men and 5.5 mmol/l for women) gave excellent AUROC, and the highest positive PV (13% for men and 9% for women) in predicting diabetes. In high risk subjects with FPG 6.1–6.9 mmol/l, 119 men (26.8%) and 39 women (28.3%) developed diabetes. Under the best cut-off points of FPG 6.39 mmol/l and A1c 5.8, AUROC and positive PV for FPG slightly decreased indicating FPG became less useful and were statistically indistinguishable from those for HbA1c in men. In fact, HbA1c was the most useful in women: HbA1c of 6.0% gave the highest positive likelihood ratio of 2.74 and larger AUROC than did FPG. Although AUROC for HbA1c was acceptable and indistinguishable from that for the combined use, HbA1c had higher specificity and positive LR than did the combined use.

Conclusions

This study demonstrated that FPG was the most useful to predict diabetes in the general population. However, in subjects with FPG 6.1–6.9 mmol/l, FPG became less useful and diagnostic performance of FPG was indistinguishable from that of HbA1c in men whereas HbA1c was the most useful in women. Thus, a two-step screening, measurement of HbA1c in association with FPG, may be useful in predicting diabetes.     

Effect of ACE inhibitors on proteinuria and renal functioning in primary glomerulopathies]

Angiotensin converting enzyme inhibitors was given to 16 patients with glomerular nephritis in whom a complete remission of nephrotic syndrome could not be achieved with immunosuppressive-anti-inflammatory therapy. Captopril in the daily dose of 25-75 mg and enalapril in the daily dose of 10 mg were administered for 1-36 months (mean 12.6 months). Daily proteinuria decreased by 40-80% comparing with baseline value in 2/3 of patients. Total protein and albumin serum levels increased simultaneously. No changes in blood creatinine were noted in patients with initially normal renal functioning except one patient. Renal functioning was stable in 50% of patients with increased blood creatinine levels (mean 200 mumol/L). Blood creatinine was increasing in the remaining patients.     

Telmisartan in the treatment of hypertension in patients with chronic renal insufficiency

The primary aim of this study was evaluation of the efficacy of telmisartan (angiotensin II receptor blocker- AT(1) blocker) on blood pressure in 10 patients with renal impairment in moderate or advanced stages of renal insufficiency and not dependent on haemodialysis. Its effect on proteinuria, renal function (represented by serum urea, creatinine, glomerular filtration), evaluation of overall therapy compliance in comparison with a previously prescribed angiotensin converting enzyme inhibitors (ACEI) were secondary aims. Considering the presence of left ventricle hypertrophy in all patients as a marker of hypertensive cardiopathy, the effect of telmisartan therapy on non-invasive cardiovascular parameters (ECG, echocardiography, and assessment of heart rate variability-HRV) was also evaluated. The study group involved 10 hypertensive patients (6 women, 4 men) with diabetic and non-diabetic renal impairment, proteinuria above 1 g/24 hours, hypertensive cardiopathy and intolerance of ACEI (cough). Telmisartan was added to their long-term antihypertensive combination therapy in a dose of 40 mg for the first 14 days, after which the dose increased to the maximal of 80 mg. The average initial daytime systolic blood pressure (SBP) was 149 +/- 19.7 mm Hg, average night-time SBP 145 +/- 23.0 mm Hg, average initial daytime diastolic BP (DBP) 90.6 +/- 2.5 mm Hg, night-time DBP 88.9 +/- 13.5 mm Hg. Average initial serum creatinine was 207.2 +/- 48.5 micromol/l, urea 15.1 +/- 4.4 mmol/l, GF 0.5 +/- 0.1 ml/s. Echocardiography revealed left ventricular (LV) hypertrophy with well preserved systolic and moderately impaired diastolic LV function. Also the HRV assessment revealed impaired neurovegetative (e.g. sympathovagal) balance. After 1 year of combination therapy with telmisartan, there was a clearly significant reduction in both SBP and DBP in both day and night-time (SBP daytime 149.6 vs.116.6 mm Hg, night-time 145.8 vs. 129.5 mm Hg; DBP daytime 90.6 vs. 83.5 mm Hg, night-time 88.9 vs. 79.3 mm Hg) and proteinuria (2.37 vs. 1.27 g/24 hour, p < 0.05). There were no significant changes in serum creatinine, urea values, and LV functions. On the other hand, further progression of the sympathovagal balance impairment was noted (continuing reduction of HRV in 9 from 10 patients), which can be described as the priority finding. The total compliance of telmisartan therapy was very good and without adverse clinical side effects. In conclusion - telmisartan reduces blood pressure and proteinuria safely and effectively in patients with various types of nephropathy in moderate or advanced stages of renal insufficiency.     

High levels of urinary vascular endothelial growth factor in women with severe preeclampsia

Elevated plasma VEGF concentrations in preeclampsia are associated with local placental ischemia and endothelial dysfunction. We investigated the urinary VEGF excretion in women with severe preeclampsia (n=37) and its relation with proteinuria compared to that in healthy pregnant (n=32) and non-pregnant women (n=30). In women with severe preeclampsia VEGF levels were 54.0 (19.9-192.4) ng/mmol creatinine, significantly (p<0.0001) higher than levels in pregnant controls (28.2 (6.7-63.0) ng/mmol creatinine) and non-pregnant controls (29.5 (10.1-59.1) ng/mmol creatinine). Proteinuria was not significantly correlated with urinary VEGF levels. In conclusion, high urinary VEGF concentrations in severe preeclampsia might reflect increased renal production of VEGF rather than elevated VEGF levels in the systemic circulation.     

Long-Term Follow-Up of Proteinuria and Estimated Glomerular Filtration Rate in HIV-Infected Patients with Tubular Proteinuria

Objective

The objective of this prospective observational study was to describe the evolution of tubular proteinuria detected in HIV-infected patients, and to evaluate the impact of tenofovir disoproxil fumarate (TDF) discontinuation.

Methods

Proteinuria and estimated glomerular filtration rate (eGFR) were followed during a median duration of 32 months, in 81 HIV-infected patients with tubular proteinuria and eGFR ≥ 60 ml/min/1.73 m² (determined using the Chronic Kidney Disease Epidemiology (CKD-EPI) Collaboration equation). Tubular proteinuria was defined by urine protein to creatinine ratio (uPCR) ≥200 mg/g and albumin to protein ratio (uAPR) <0.4.

Results

Twenty per cent of patients had persistence of tubular proteinuria: TDF continuation was the main factor associated with this persistence [OR 9.0; 95%CI: 1.9–41.4; p = 0.01]. Among the 23 patients who discontinued TDF, uPCR returned below the threshold of 200 mg/g in 11 patients. Overall, eGFR decreased with a mean rate of decline of 3.8 ml/min/1.73m²/year. The decline in eGFR was lesser after discontinuation of TDF (5.8 ml/min/1.73m²/year during TDF exposure versus 3 ml/min/1.73m²/year after TDF discontinuation; p = 0.01).

Conclusions

The continuation of TDF was the main factor associated with the persistence of proteinuria. Moreover, proteinuria was normalized in only half of the patients who discontinued TDF. The clinical significance of TDF-related low level of proteinuria as a factor associated with renal disease progression and bone loss remains poorly understood.     

Renal Effects and Underlying Molecular Mechanisms of Long-Term Salt Content Diets in Spontaneously Hypertensive Rats

Several evidences have shown that salt excess is an important determinant of cardiovascular and renal derangement in hypertension. The present study aimed to investigate the renal effects of chronic high or low salt intake in the context of hypertension and to elucidate the molecular mechanisms underlying such effects. To this end, newly weaned male SHR were fed with diets only differing in NaCl content: normal salt (NS: 0.3%), low salt (LS: 0.03%), and high salt diet (HS: 3%) until 7 months of age. Analysis of renal function, morphology, and evaluation of the expression of the main molecular components involved in the renal handling of albumin, including podocyte slit-diaphragm proteins and proximal tubule endocytic receptors were performed. The relationship between diets and the balance of the renal angiotensin-converting enzyme (ACE) and ACE2 enzymes was also examined. HS produced glomerular hypertrophy and decreased ACE2 and nephrin expressions, loss of morphological integrity of the podocyte processes, and increased proteinuria, characterized by loss of albumin and high molecular weight proteins. Conversely, severe hypertension was attenuated and renal dysfunction was prevented by LS since proteinuria was much lower than in the NS SHRs. This was associated with a decrease in kidney ACE/ACE2 protein and activity ratio and increased cubilin renal expression. Taken together, these results suggest that LS attenuates hypertension progression in SHRs and preserves renal function. The mechanisms partially explaining these findings include modulation of the intrarenal ACE/ACE2 balance and the increased cubilin expression. Importantly, HS worsens hypertensive kidney injury and decreases the expression nephrin, a key component of the slit diaphragm.     

HbA1c Test as a Tool in the Diagnosis of Gestational Diabetes Mellitus

Aims

Gestational diabetes mellitus (GDM) is a prevalent and potentially serious condition which may put both mothers and neonates at risk. The current recommendation for diagnosis is the oral glucose tolerance test (OGTT). This study aimed to determine the usefulness of HbA1c test as a diagnostic tool for GDM as compared to the traditional criteria based on the OGTT.

Methods

This was a diagnostic test accuracy study. We performed OGTT and HbA1c test in women attending prenatal visits at a tertiary hospital. GDM was defined according to WHO1999 or ADA/WHO 2013 criteria. ROC curve was used to evaluate the diagnostic performance of HbA1c. Sensitivity, specificity and likelihood ratios for different HbA1c cut-off points were calculated.

Results

Of the 262 women in the third trimester of gestation enrolled in the study, 86 (33%) were diagnosed with GDM. Only five of these women presented HbA1c ≥48 mmol/mol (6.5%). This cut-off point presented 100% specificity but very low sensitivity (7%). Based on ROC curve, and considering OGTT as the reference criterion, HbA1c ≥40 mmol/mol (5.8%) showed adequate specificity in diagnosing GDM (94.9%) but low sensitivity (26.4%). Unlike, HbA1c values of 31 mmol/mol (5.0%) presented adequate sensitivity (89.7%) but low specificity (32.6%) to detect GDM. For women with HbA1c ≥40 mmol/mol (5.8%), the positive and negative likelihood ratios were 5.14 (95%CI 2.49–10.63) and 0.78 (0.68–0.88), respectively. The post-test probability of GDM was about 40%, representing a 4.0-fold increase in the mean pre-test probability. This cut-off point could eliminate the need for the unpleasant and laborious OGTT tests in almost one third of cases, as 38% of patients with GDM may be diagnosable by HbA1c test alone.

Conclusions

Our results show that combined HbA1c and OGTT measurements may be useful in diagnosing GDM.