Increased end-stage diabetic nephropathy in Indo-Asian immigrants living in the Netherlands

AIMS/HYPOTHESIS

We aimed to investigate the risk of end-stage diabetic nephropathy due to Type II (non-insulin-dependent) diabetes mellitus in Indo-Asian immigrants from Surinam.

METHODS

A demographically based case-control study was carried out in Surinamese Indo-Asian immigrants and Dutch Caucasian subjects. All patients with end-stage diabetic nephropathy who had started dialysis between 1990 and 1998 were identified through a national registry of all patients entering a renal replacement program in the Netherlands. The general population of native Dutch and Surinamese Indo-Asians were considered the control subjects.

RESULTS

Among Indo-Asian immigrants, the age adjusted relative risk of end-stage diabetic nephropathy was 38 (95 % CI 16 to 91) compared with the native Dutch population. The duration of diabetes until the start of dialysis treatment was similar in both ethnic groups, about 17 years.

CONCLUSION/INTERPRETATION

The Indo-Asian subjects had a nearly 40-fold increase in the risk for end-stage diabetic nephropathy due to Type II diabetes, compared with the native Dutch population. This was higher than expected on the basis of the eightfold higher prevalence of diabetes in the Indo-Asian population. The similar duration of diabetes until the start of dialysis treatment in both ethnic groups supports the hypothesis of a higher incidence of diabetic nephropathy in the Indo-Asian diabetic population. Early and frequent screening for diabetes and microalbuminuria is recommended in Indo-Asian subjects.

[Protein restriction in diet therapy in chronic kidney insufficiency]

Dietary protein restriction represents an important new development in the treatment of chronic kidney disease during the last ten years. The dogma that chronic renal failure is always progressive appears to be broken. In clinical practice this mode of therapy is now established in early stages of renal failure. The precise indications, however, remain to be discussed ['Are all patients with chronic renal failure candidates for low-protein diets?']. The pathophysiological background of the diets is only partly elucidated. The main problem with low-protein diets is the compliance of the patients which is frequently insufficient. Studies are underway to answer some of these remaining open questions. This review summarises the current views on practical aspects of low-protein diets in chronic renal failure, and arguments for a more widespread application of this physiologic therapy are presented.

Dietary protein restriction in chronic renal failure: an update

In recent years dietary protein restriction (DPR) to slow down the progression rate of chronic renal disease has been a major field in nephrological science. In this update a brief historical overview is given, as well as a critical review regarding the now available data from clinical trials. Furthermore, the theoretical backgrounds of DPR are discussed. It is concluded that DPR has profound effects on the kidney. In certain diseases, especially primary glomerular disease, the beneficial effect seems proven. However, many questions remain to be answered, e.g. how to apply reliable statistics in chronic renal failure, how to obtain and monitor patient compliance, and the definition of the exact target group since the diet has a selective effect. Most of these questions will be answered in the coming years when data becomes available from large scale multicenter trials. Awaiting these results, proposals for the treatment with diet are made, based on the facts that are now to our knowledge.

Relationship between proteinuria and response to low protein diets early in chronic renal failure

In a prospective, randomized trial on the use of protein-restricted diets in chronic renal failure the impact of the protein intake on proteinuria was investigated. Furthermore, the effect on the progression rate of renal disease in patients with low versus high proteinuria was assessed. It is concluded, firstly, that protein restriction reduces protein excretion substantially. Secondly, over 18 months follow-up, especially patients with low protein excretion appeared to respond to the diet. In patients with heavy proteinuria the diet might have beneficial effects in the long term.

Absence of diabetes in a rural West African population with a high carbohydrate/cassava diet

1028 (99%) of the 1038 inhabitants of the West African village of Agbave and a random sample of 353 (12.4%) of the population of 2850 in Kati, another West African village, were screened for diabetes. Also recorded were their anthropometric data, dietary habits, possession of antibodies to malaria, and serum IgG concentrations. About 85% of the study population consumed cassava root at least once a day. The mean (SD) capillary random blood glucose concentration was 5.1 (1.1) mmol/l in men and 5.1 (0.6) in women. The mean (SD) body mass index was 20.2 (1.8) in men and 20.7 (2.3) in women. The mean blood glucose was similar whether cassava was consumed once daily, more than once daily, or less than once daily. None of the 1381 subjects examined had diabetes. This finding suggests that a high carbohydrate/cassava intake (84% of a mean daily supply of 1916 calories) combined with a low protein consumption (8% of caloric supply) does not cause diabetes. This does not support the World Health Organisation hypothesis that malnutrition-related diabetes exists, at least not in this West African rural population.

The pathology and pathogenesis of malignant atrophic papulosis (Degos' disease). A case study with reference to other vascular disorders

The morphology and immunohistology in a case of malignant atrophic papulosis (Degos' disease), a rare vascular disorder of unknown etiology, are described. The vascular lesions affected middle class and small arteries and veins throughout the body and were histologically characterized by intimal proliferation in the absence of any appreciable inflammation. The lesions were categorized as early, intermediate or late. Early lesions consisted of cellular proliferation and edema of the intima with signs of immune complex deposition (IgM, C3). Thrombosis was occasionally present as a secondary phenomenon in the affected vessel segments. In intermediate lesions the edema decreased and smooth muscle proliferation became apparent. Late lesions consisted of acellular intimal sclerosis with hyalinization and narrowing or obliteration of the vascular lumen. The media of the vessels remained always intact. In comparing these features to the pathology and pathogenesis of other vascular disorders they resembled the vascular lesions in a murine model of lupus erythematodes in which also considerable intimal proliferation occurred with thrombotic occlusion, but without appreciable inflammation. The murine model is associated with sustained low levels of circulating immune complexes and it is tempting to assume the same for Degos' disease. The notion of an immune complex mediated non-inflammatory condition underlying this severe and often fatal vascular disorder of mainly young males may contribute to the eventual finding of a successful therapeutical regimen.

Renal hemodynamics during separate and combined infusion of amino acids and dopamine

Healthy volunteers (N = 9) and patients with varying degrees of renal insufficiency (N = 36) were given a low dose of dopamine and/or amino acids intravenously during a simultaneous measurement of the glomerular filtration rate and the effective renal plasma flow. Dopamine infusion led to a rise in the glomerular filtration rate and a fall in the filtration fraction. Infusion of amino acids was accompanied by an increase in the glomerular filtration rate while the filtration fraction remained unchanged or increased slightly. The highest values for the glomerular filtration were obtained during the combined infusion of amino acids and dopamine. A reserve in filtration capacity was not or hardly present in patients with moderate (GFR 30 to 90 mliter/min/1.73 M2) to severe (GFR less than 30 mliter/min/1.73 M2) renal insufficiency. We conclude that dopamine decreases total renal vascular resistance while amino acids mainly reduce the tone of afferent arterioles. As amino acids and dopamine seem to be additive in their effects on the glomerular filtration rate, we recommend the combined infusion of these two stimuli to measure renal reserve filtration capacity.

The effect of low-dose dopamine on renal haemodynamics in patients with type 1 (insulin-dependent) diabetes does not differ from normal individuals

It is well known that patients with Type 1 (insulin-dependent) diabetes exhibit both increased glomerular filtration rate and effective renal plasma flow, which can be found even when these patients are well controlled. Usually this is attributed to a decrease in renal vascular resistance and/or to enlarged kidney size and glomerular volume. Among the factors which govern glomerular filtration rate, renal plasma flow is most important. Renal plasma flow increases if renal vascular resistance decreases. The latter might exist in insulin-dependent diabetes mellitus because of either a predominantly afferent or a predominantly efferent vasodilatation. Dopamine is an agent which causes predominantly efferent vasodilatation. Therefore, the effects of infusing a low dose of dopamine on glomerular filtration rate and effective renal plasma flow in 12 well-controlled patients with Type 1 (insulin-dependent) diabetes and 28 healthy volunteers were compared to investigate whether the increased glomerular filtration rate in Type 1 diabetes is caused by an efferent vasodilatation. The median increase in glomerular filtration rate during dopamine infusion amounted to 13.0% in diabetic patients and 12.5% in healthy control subjects (n.s.). It is concluded that the elevated glomerular filtration rate in well-controlled Type 1 diabetes is not caused by a predominantly efferent vasodilatation.

Effect of intravenous infusion of low-dose dopamine on renal function in normal individuals and in patients with renal disease

A low dose of dopamine was infused in 28 normal volunteers and in 137 patients with varying degrees of renal insufficiency during a routine measurement of the glomerular filtration (GFR) and the effective renal plasma flow (ERPF). Dopamine infusion led to an increase in ERPF and GFR and to fall in the filtration fraction. The effect of dopamine on renal function was most pronounced if the baseline GFR was normal. However, healthy individuals showed greater increases in both ERPF and GFR than renal patients with a comparable baseline GFR. In renal patients no effect was observed if the baseline GFR was below 50 ml/min/1.73 m2. Firstly, it is concluded that already early in renal disease there exists a diminished reserve filtration capacity. Secondly, if the GFR is less than 50 ml/min/1.73 m2, the renal reserve filtration capacity seems to be exhausted.

Testing renal reserve filtration capacity with an amino acid solution

In healthy individuals and in patients with varying degrees of impaired renal function, glomerular filtration rate (GFR) and effective renal plasma flow were measured before and during infusion of an amino acid solution (Vamin N). GFR increased during amino acid infusion in healthy individuals while the filtration fraction (FF) remained constant. However, in patients with impaired renal function no significant changes in GFR were observed. The FF increased slightly. We conclude that amino acid infusion can increase GFR, possibly by utilization of 'dormant cortical nephrons' together with a rise in net ultrafiltration pressure of other filtrating glomeruli, both due to afferent vasodilatation. Thus, amino acid administration can be used to test the presence of reserve filtration capacity.

Prospective randomised trial of early dietary protein restriction in chronic renal failure

In a prospective randomised study of 228 patients with various renal diseases, early moderate dietary protein restriction retarded the development of end-stage renal failure. 149 patients were followed up for at least 18 months; the protein-restricted patients showed falls in serum urea and phosphate concentrations and in the 24 h excretion of urea, phosphate, and protein. Regression analysis of the reciprocals of serum creatinine against time showed that the average rate of decrease in reciprocal creatinine was three to five times lower in the protein-restricted groups than in the control groups. These results confirm that moderate dietary protein restriction is an acceptable and effective way of delaying functional renal deterioration. The finding has implications for the management of chronic renal insufficiency.