Early detection and treatment of diabetic nephropathy

Renal involvement in diabetes, known as diabetic nephropathy (DN), is a progressive disease and occurs as a result of direct and indirect effects of hyperglycemia. DN is a serious public health concern because it is the leading cause of end stage renal disease (ESRD) in most developed countries and is associated with increased cardiovascular mortality and morbidity. DN is characterized by an initial period of glomerular hyperfiltration, associated with progressively increasing proteinuria, followed by a gradual decline in glomerular filtration rate, resulting in ESRD. Prevention of DN depends on awareness of risk factors for DN, screening for microalbuminuria and hypertension, monitoring glycemic control, and initiating or modifying treatment as needed. Risk factors for development of DN include hyperglycemia, hypertension, positive family history of nephropathy and hypertension, and smoking. Significant advances have been made in recent years in understanding the pathogenesis of DN, raising the possibility that newer therapies may prevent or slow the progression of DN.     

Long-term results of pre-emptive liver transplantation in primary hyperoxaluria type 1

In primary hyperoxaluria type 1 (PH 1), deficiency or mistargeting of hepatic alanine glyoxylate aminotransferase (AGT) results in over-production of oxalate and hyperoxaluria, leading to nephrocalcinosis and development of end-stage renal disease (ESRD) in the majority of patients. Renal transplantation (Tx) alone carries a high risk of disease recurrence as the metabolic defect is not cured. Therefore, combined liver/kidney Tx is recommended for patients with ESRD. An alternative approach is to cure PH 1 by pre-emptive isolated liver Tx (PLTx) before ESRD has occurred, but this approach has been carried out only occasionally and there are no uniformly accepted recommendations concerning the timing of this procedure. We report follow-up 3-5.7 yr after performing successful PLTx in four children (at the age of 3-9 yrs) with PH 1 prior to the occurrence of ESRD (glomerular filtration rate [GFR] range 27-98 mL/min/1.73 m2). There was no mortality or long-term morbidity associated with the Tx procedure. Plasma and urinary oxalate levels normalized rapidly within 4 weeks, and renal function did not deteriorate under immunosuppression, even in one patient with advanced chronic renal failure (GFR 27 mL/min/1.73 m2) who showed a stable course for more than 5.7 yrs. Although treatment must be individualized in this severe metabolic disorder, and PLTx has to be regarded as an invasive procedure, we consider that PLTx should be offered and considered early in the course of PH 1. PLTx cures the metabolic defect in PH 1 and can help to prevent, or at least delay, the progression to ESRD and systemic oxalosis.     

Persisting glomerular hyperfiltration in short-term diabetic children without microalbuminuria

The renal function in a group of diabetic children (n=29;age;4-17 yr; IDDM duration: 1,5-13 yr) was studied with a 3 year interval. At the first evaluation glomerular filtration rate (GFR) as assessed by inulin clearance was significantly increased compared to control values (167 +/- 32 vs. 124 +/- 18 ml/min/1.73 m2; pl less than 0.01). Eighteen out of 29 children exhibited a glomerular hyperfiltration (GFR greater than 160). Three years later mean GFR was identical (169 +/- 25 ml/min/1.73 m2) and 16 children were hyperfiltrating. Among them, 11 have had a persisting glomerular hyperfiltration over the 3-year period. Renal plasma flow (RPF) was positively correlated to GFR (r=0.7; p less than 0.01) and remained elevated at both evaluations (794 +/- 163 and 812 +/- 157 ml/min/1.73 m2, p greater than 0.01 vs, control values). When the children were separated into 3 groups according to IDDM duration no significant differences were observed in the results for GFR and RPF, Mean urinary albumin excretion was comparable at the 3-year interval, and not significantly different from the control values (5.2 +/- 3.7 and 8.2 +/- 6.6 respectively vs. 8.65 +/- 4 microgram/min). None of the children demonstrated a persistent microalbuminuria. This study reveals a high proportion of diabetic children with a persisting glomerular hyperfiltration, without any other symptom of incipiens nephropathy, If elevated GFR plays an important role in the development of diabetic nephropathy, this study emphasizes the value of regular evaluation of renal function in diabetic children.     

Short-term protein loading in diabetics with a ten-year duration of disease

The concept of renal functional reserve has recently been introduced. To test this ability of the kidneys to increase the glomerular filtration rate (GFR) above the baseline level, the GFR response to short-term protein load was measured. Recent studies have provided conflicting data concerning the GFR response to a protein load in insulin-dependent diabetics who are known to have increased baseline GFRs. Thus, we studied nine insulin-dependent diabetics with a disease of at least a ten-year duration (none were hypertensive or proteinuric) and compared their data with those of five nondiabetic controls with normal renal function. All the diabetics, except one, showed a significant increase in GFR (mean +/- SEM, 60 +/- 9 to 74 +/- 14 mL/min/sq m); the controls also had increased GFRs (mean +/- SEM, 53 +/- 6 to 69 +/- 6 mL/min/sq m). The one patient who demonstrated no rise in the GFR had the lowest GFR measured, 33 mL/min/sq m. To explore the mechanism of this response, we measured the plasma levels of putative mediators glucagon and human growth hormone. Although glucagon showed the expected rise after the protein meal, the variability was so large that no statistically significant relationship could be identified. Human growth hormone remained constant and low in the controls and showed more variability and was higher in the diabetics; again, no relationship to the GFR could be demonstrated. Thus, our data demonstrated a normal response to a short-term protein load by a group of well-defined diabetic subjects who would be at risk to show subtle renal abnormalities.     

Evaluation and treatment of chronic renal failure

Chronic renal failure (CRF) is the irreversible deterioration of renal function that gradually progresses to end stage renal disease (ESRD). The chief causes of CRF include obstructive uropathy, primary glomerular diseases, reflux nephropathy and hypoplastic or dysplastic kidneys. Progressive hyperperfusion and hyperfiltration causes increasing glomerular injury and further renal damage. Symptoms of CRF are usually seen when GFR is between 10–25% of normal. Children with severe CRF often suffer from failure to thrive, growth retardation, acidosis, anemia and renal osteodystrophy. Management of CRF aims at retarding progression of renal damage and treatment of complications related to renal dysfunction. Measures suggested to retard progression include protein restriction, strict control of hypertension, use of angiotensin converting enzyme inhibitors and control of hyperlipidemia. Appropriate amounts of protein and calories are recommended to prevent growth failure. Nutritional supplements are often required. The availability of recombinant erythropoietin, calcitriol and human growth hormone has significantly improved the management of these patients. Once ESRD supervenes, renal replacement therapy in the form of chronic peritoneal or hemodialysis and transplantation is necessary.     

先天性肾积水患儿肾脏水通道蛋白表达与肾实质厚度和肾小球滤过率的相关性

目的：探讨先天性肾积水患儿肾脏水通道蛋白AQP1-4 的表达与肾实质厚度和肾小球滤过率（GFR）变化之间的关系。方法：利用Western blot检测AQP1-4蛋白在10例先天性肾积水患儿(年龄62.3±18.3个月)10个肾组织和6例来自肾母细胞瘤手术切除患儿的正常肾脏组织(年龄62.7±17.1个月)中的相对表达量。同时对患侧肾脏肾实质厚度和GFR进行评估。积水肾脏AQP1-4表达与GFR以及肾实质厚度之间进行Pearson相关分析检验。结果：肾积水组AQP1-4蛋白相对表达均明显低于正常组（P＜0.05）。B超测量术前积水侧肾脏肾实质厚度平均为4.59±2.25 mm。99mTc-DTPA 测定积水侧肾脏GFR较对侧肾脏明显下降（40±12 mL/min vs 105±20 mL/min, P＜0.05）。积水组肾脏中AQP1-4蛋白相对表达量与肾实质厚度之间呈正相关,与患侧肾脏GFR之间亦呈正相关。积水侧肾脏肾实质厚度与GFR之间呈正相关。结论：先天性积水患儿肾脏AQP1-4蛋白表达下降,其表达量与肾实质厚度和肾脏GFR的变化呈正相关。     

Can management strategies alter the course of diabetic nephropathy?

End Stage Renal Disease (ESRD) is a common consequence of diabetic nephropathy (DN). DN is the major cause of death in patients with IDDM, accounting for greater than 40% of deaths with this form of diabetes. There is no clearly documented therapeutic technique that will prevent or reverse progressive renal damage in IDDM. While pancreatic transplantation and “cure” of diabetes in experimental animals may be associated with some histological reversal of renal pathology, this has not been documented in humans. Most studies agree that once diabetic renal disease is present (as documented by proteinuria), progression is inevitable, albeit the rate of progression may be altered by different therapeutic methods. There is considerable hope that “tight metabolic control” will prevent the initial damage that leads to DN and ESRD, but evidence remains inconclusive. There is some evidence that careful monitoring for microalbuminuria will allow for very early detection of damage and alterations in therapy. Our studies have documented a decrease in both morbidity and mortality in IDDM in patients who have been competitive athletes, suggesting that promotion of physical fitness may be a valuable means of delaying progression of renal disease while control of BP delays progression. Early detection and aggressive therapy is recommended. Some studies utilizing diets low in sodium and/or protein appear beneficial but more studies are needed before pediatric application     

Persisting Glomerular Hyperfiltration in Short-term Diabetic Children without Microalbuminuria

ABSTRACT. The renal function in a group of diabetic children ( n =29; age: 4–17 yr; IDDM duration: 1.5–13 yr) was studied with a 3 year interval. At the first evaluation glomerular filtration rate (GFR) as assessed by inulin clearance was significantly increased compared to control values (167±32 vs. 124±18 ml/min/1.73 m²; p ≤0.01). Eighteen out of 29 children exhibited a glomerular hyperfiltration (GFR ≥ 160). Three years later mean GFR was identical (169±25 ml/min/1.73 m²) and 16 children were hyperfiltrating. Among them, 11 have had a persisting glomerular hyperfiltration over the 3-year period. Renal plasma flow (RPF) was positively correlated to GFR ( r =0.7; p ≤0.01) and remained elevated at both evaluations (794±163 and 812±157 ml/min/1.73 m², p ≤0.01 vs. control values). When the children were separated into 3 groups according to IDDM duration no significant differences were observed in the results for GFR and RPF. Mean urinary albumin excretion was comparable at the 3-year interval, and not significantly different from the control values (5.2±3.7 and 8.2±6.6 respectively vs. 8.65±4 |ig/min). None of the children demonstrated a persistent microalbuminuria. This study reveals a high proportion of diabetic children with a persisting glomerular hyperfiltration, without any other symmptom of incipiens nephropathy. If elevated GFR plays an important role in the development of diabetic nephropathy, this study emphasizes the value of regular evaluation of renal function in diabetic children.     

Allograft diabetic nephropathy may progress to end-stage renal disease

Mesangial expansion and glomerular basement membrane thickening characteristic of diabetic nephropathy recur in diabetic recipients of renal allografts from non-diabetic donors but progression to renal failure is minimally documented. Three female renal allograft recipients (aged 40, 62 and 73 yr), who developed end-stage renal disease (ESRD) due to recurrent diabetic nephropathy (two patients) and de novo diabetes (one patient) are reported. Onset of proteinuria, uncontrolled hypertension, azotemia, renal allograft pathologic findings and the need for hemodialysis were analyzed. None of the kidney donors (one cadaver, two living related) had known diabetes or perturbed glucose metabolism pre-transplantation. The three patients presented had different varieties of diabetes; type 1, type 2 and new onset diabetes after transplantation (NODAT). In each subject, proteinuria was detected by dipstick at a mean of 8.3 yr (range 8-9) post-transplantation and increased to the nephrotic range (3.7-4.8 g/day) inducing hypoalbuminemia and azotemia. A histopathologic diagnosis of allograft diabetic nephropathy was made in a mean of 11.7 yr (range 10-14), based on glomerular basement membrane thickening, nodular and diffuse intercapillary glomerulosclerosis, arteriolosclerosis, and tubular atrophy with marked tubular basement membrane thickening characteristic of advanced diabetic nephropathy. All three patients manifested uremia and resumed hemodialysis. Two patients died from sepsis within 2 months and one patient died 2.5 yr later after resumption of maintenance hemodialysis. We infer that recurrent or de novo diabetic nephropathy in renal allografts follows a clinical decade-long course irrespective of diabetes. Reports of ESRD due to allograft diabetic nephropathy (ADN) have been limited because of shorter survival of diabetic transplant recipients and few kidney biopsies performed in patients with chronic allograft dysfunction. The occurrence of allograft diabetic nephropathy in some, but not all patients, however, suggests that individual genetic variability modulates disease expression.     

Short-term effect of low and high protein intake on renal function in children with renal disease

The short-term effect of different levels of protein intake on renal function was investigated in 18 children with moderately (51-85 ml/min/1.73 m2 BSA) or severely (9-50 ml/min/1.73 m2 BSA) reduced glomerular filtration rates (GFR). The GFR and effective renal plasma flow (ERPF), estimated as the clearances of respectively inulin and para-aminohippuric acid during uncontrolled (2-2.5 g/kg bw), low (1.2 g/kg bw for 12 days) and high (3-5 g/kg bw for 24 h) protein intake were determined by a standard clearance method employing continuous infusion and spontaneous voiding. There were no significant differences in GFR or ERPF during uncontrolled and low protein intake. During high protein intake the GFR and ERPF increased significantly in patients with GFRs above 50 ml/min/1.73 m2 BSA and ERPFs above 150 ml/min/1.73 m2 BSA. It is concluded that these findings might indicate a functional reserve capacity in children with only moderately reduced renal function.     

Hypothyroidism mimicking chronic renal failure in reflux nephropathy

An adolescent with a history of pyelonephritis and renal scarring had antireflux surgery at the age of 2.5 years. His serum creatinine was high at the age of 14 years (133 micromol/l; glomerular filtration rate (GFR) 56 ml/min x 1.73 m(2)), and reflux nephropathy with chronic renal failure was diagnosed. Because of a fall in height velocity, endocrinological investigations were performed six months later which showed hypothyroidism caused by autoimmune thyroiditis. Substitution with thyroxine was started; renal function improved to normal six months later (GFR 108 ml/min x 1.73 m(2)). Metabolic changes of hypothyroidism led to a reduction of GFR in this patient and mimicked chronic renal failure.     

Hypothyroidism mimicking chronic renal failure in reflux nephropathy.

An adolescent with a history of pyelonephritis and renal scarring had antireflux surgery at the age of 2.5 years. His serum creatinine was high at the age of 14 years (133 micromol/l; glomerular filtration rate (GFR) 56 ml/min x 1.73 m(2)), and reflux nephropathy with chronic renal failure was diagnosed. Because of a fall in height velocity, endocrinological investigations were performed six months later which showed hypothyroidism caused by autoimmune thyroiditis. Substitution with thyroxine was started; renal function improved to normal six months later (GFR 108 ml/min x 1.73 m(2)). Metabolic changes of hypothyroidism led to a reduction of GFR in this patient and mimicked chronic renal failure.     

Glomerular filtration rate in children following renal transplantation

Most studies evaluating renal function post-renal transplantation in children have used serum creatinine (S(Cr)) or estimates of its clearance (C(SCH)). When renal function is impaired both S(Cr) and the C(SCH) overestimate glomerular filtration rate (GFR), especially during cyclosporine therapy. This study measured GFR in 64 children (age range: 4-19 years) with stable renal function who received renal allografts at the Childrens Medical Center of Dallas, 31 from live related donors (LRD) and 33 from cadaveric donors (CAD). 125I-iothalamate clearance (C(IO)) was used as the reference standard for measuring GFR. Data from 100 C(IO) studies, were analyzed and results reported as mean +/- S.E.M. C(IO) performed during the first year after renal transplantation in 23 children who received allografts from LRD was 72.4+/-5.5 ml/min per 1.73 m2 compared to 50.4+/-7.4 ml/min per 1.73 m2 in 18 children who received allografts from CAD (p<0.05). Beyond the first year post-renal transplantation there was no difference in C(IO) between LRD and CAD allografts. When S(Cr) was compared to C(IO), the relationship was nonlinear. C(IO) was also compared to the simultaneous estimation of creatinine clearance by C(SCH). The overestimation of GFR by C(SCH) was inversely proportional to the level of renal function. When renal function was normal or mildly reduced (C(IO) > 50 ml/min per 1.73 m2), C(SCH) closely approximated C(IO). When renal function was moderately to severely curtailed (C(IO) < or = 50 ml/min per 1.73 m2), C(SCH) overestimated C(IO) by 43.6+/-5.6%. The study concludes that in children with renal transplant: 1) C(IO) is higher in allografts from LRD compared to CAD kidneys only in the first 12 months following renal transplantation; 2) S(Cr) is a poor predictor of C(IO); and 3) C(SCH) consistently overestimates GFR children following renal transplantation unless renal function is normal or only mildly decreased.     

Glomerular filtration and tubular reabsorption of glucose in insulin-dependent diabetes in children

Although glycosuria is important in the control of diabetes in children, few studies clearly show its significance as compared to glycemia. The aim of the present study was therefore to determine the two parameters that control glucose presence in urine, i.e. glucose glomerular filtration rate (GFR) and tubular reabsorption (JrG). GFR was measured by using a 110 min polyfructosan perfusion in 96 diabetic children and adolescents. The results are as follows: 1) In this population there is a significant correlation (p less than 0.01) between the quantity of glucose in urine and mean glycemia during the test; 2) polyfructosan clearance that reflects GFR in diabetic children without renal complication is 2.11 +/- 0.04 ml/s 1.73 m2, or 126 +/- 2.4 ml/min 1.73 m2 (mean +/- SEM); it is higher than in the reference values already published; 3) JrG is correlated with glucose filtered load (p less than 0.01), GFR (p less than 0.01) and sodium reabsorption (p less than 0.01). The ratio JrG/GFR could be substituted for the classical concept of "renal threshold", as it can be easily measured and may help in interpreting glycosuria in some diabetic children. To conclude, in IDD children, the parameters controlling glycosuria may be studied by a simple method. The clinical value of such renal exploration has still to be determined.     

Short-Term Effect of Low and High Protein Intake on Renal Function in Children with Renal Disease

ABSTRACT. The short-term effect of different levels of protein intake on renal function was investigated in 18 children with moderately (51–85 ml/min/1.73 m² BSA) or severely (9–50 ml/min/1.73 m² BSA) reduced glomerular filtration rates (GFR). The GFR and effective renal plasma flow (ERPF), estimated as the clearances of respectively inulin and para-aminohippuric acid during uncontrolled (2-2.5 g/kg bw), low (1.2 g/kg bw for 12 days) and high (3–5 g/kg bw for 24 h) protein intake were determined by a standard clearance method employing continuous infusion and spontaneous voiding. There were no significant differences in GFR or ERPF during uncontrolled and low protein intake. During high protein intake the GFR and ERPF increased significantly in patients with GFRs above 50 ml/min/1.73 m² BSA and ERPFs above 150 ml/min/1.73 m² BSA. It is concluded that these findings might indicate a functional reserve capacity in children with only moderately reduced renal function.     

Evaluation of a height/plasma creatinine formula in the measurement of glomerular filtration rate.

The clinical usefulness of the quantity height (cm)/plasma creatinine (Ht/Pcr) as a predictor of glomerular filtration rate (GFR) was investigated in 163 children with varying levels of renal function. Plasma creatinine levels (mumol/l) were measured by an automated reaction rate method. The results indicate that in rather more than half the children studied, an estimate of GFR adequate for ordinary clinical purposes will be obtained from Ht/Pcr, or from the derived formula GFR (ml/min per 1.73 m2) = 40 Ht/Pcr. The accuracy of the prediction is greatest in children with reduced function (GFR less than 80 ml/min per 1.73 m2) and in this group of patients a change of GFR of 19 ml/min per 1.73 m2 or more is reliably detected by this method. We conclude that Ht/Pcr is a clinically useful aid to the estimation of renal function, reducing the need for formal GFR measurements by at least half.     

内皮素在1型糖尿病大鼠中的动态变化及其与早期肾脏病变的关系

目的　探讨内皮素 (ET)在糖尿病大鼠中的动态变化及其与肾脏形态学改变的关系。方法　将40只Wistar大鼠随机分为糖尿病组和正常对照组。采用链佐脲菌素 (STZ)诱导的糖尿病大鼠模型 ,在模型成功后 4、8、12周分别测定血和肾组织ET含量。同时取肾组织进行光镜和透射电镜检查。结果　糖尿病大鼠血浆和肾组织中ET含量 4、8、12周进行性增高 ,与对照组比较均有显著差异 ( P <0 .0 5 ) ;肾组织形态学发生明显改变 ,定量分析显示糖尿病组肾小球平均截面积和基底膜厚度均高于正常对照组 (P <0 .0 5 )。相关分析表明 ,肾组织ET与尿蛋白排泄量、基底膜厚度呈正相关 ,与肾小球滤过率 (GFR)呈负相关。结论　糖尿病大鼠存在血管内皮分泌功能紊乱及肾组织的早期病理改变。内皮收缩因子ET与糖尿病早期肾脏形态学改变有关     

Renal prostaglandin E2 synthesis and degradation in the developing rat

Postnatal development of glomerular filtration rate (GFR) and renal blood flow is associated with a fall in renal vascular resistance that may be mediated by vasoactive substances. We examined differences in the regulation of one such substance, prostaglandin E2 (PGE2). The present studies examined renal cortical and medullary PGE2 synthesis and degradation in rats aged 20 days (30.7 g), 31 days (101 g), and 120 days (413 g). PGE2 synthesis in cortical microsomes was highest in 20-day-old rats compared to 31- and 120-day-old rats. In contrast, medullary PGE2 synthesis was lowest in 20-day-old rats compared to 31- and 120-day-old rats. Both cortical and medullary PGE2 degradation were highest in 20-day-old rats and decreased with age. Despite demonstrating significant age-dependent differences in cortical and medullary PGE2 synthesis, 11 days of aspirin given between age 20-31 days blocked PGE2 synthesis in cortex and medulla by 60 and 76%, respectively, but GFR was similar to control 31-day-old rats (0.78 +/- 0.04 ml/min/g kidney weight, aspirin-treated, versus 0.85 +/- 0.03 ml/min/g kidney weight, control), suggesting that observed age-dependent differences in renal PGE2 synthesis is not a major determinant of development of GFR. A more important determinant of GFR may be age- related differences in renal cortical prostaglandin turnover.     

Beta 2 microglobulin. Index of glomerular filtration in children

121 assays for plasma Beta 2 microglobulin (B2M) levels were carried out with an immuno-enzymatic technique in 94 children whose ages ranged from 13 months to 18 years and whose renal functions showed various levels of renal impairment. In the 37 children with normal glomerular filtration rate, plasma B2M level was 1.58 +/- 0.48 mg/l (mean +/- 1 SD) and no significant differences were found according to sex, ages or heights. In the 29 children with glomerular filtration rate (GFR) ranging from 20 to 100 ml/min/1.73 m2, there was a significant correlation between B2M and the inulin clearance, plasma creatinine level and creatinine clearance (p less than 0.001). In 28 patients presenting with terminal renal failure, plasma B2M levels were significantly higher in children undergoing hemodialysis than in those under chronic peritoneal dialysis. These results indicate that B2M levels are as good an index of glomerular filtration rate as serum creatinine whereas its assay uses a long and difficult technique.     

Renal histological changes in relation to renal function and urinary protein excretion in IgA nephropathy.

Renal function and urinary protein excretion (UPE) were investigated at the time of kidney biopsy in 24 children with IgA nephropathy. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by clearances of inulin and para-aminohippuric acid. For UPE albumin, IgG, beta 2 microglobulin, and creatinine were analysed. Glomerular global/segmental sclerosis and crescents in the biopsy specimens were assessed, and glomerular and tubulointerstitial changes classified on a five degree scale. The patients with tubulointerstitial or mesangial biopsy changes or glomerular sclerosis had significantly lower GFR than those without corresponding lesions. Patients with segmental sclerosis also had higher excretion rates of IgG, which increased with increasing segmental sclerosis. Six patients had GFRs below 2SD of the controls. Within the group of patients with reduced GFR overt albuminuria, a raised excretion rate of IgG, interstitial fibrosis, and advanced mesangial lesions were more frequent. A rising excretion rate of IgG seems to indicate both reduced GFR and increasing segmental glomerulosclerosis and may be a marker of progressive disease.