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Query: UMLS:C0011881 (diabetic nephropathy)
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The earliest manifestations of clinical diabetic nephropathy, including proteinuria, hypertension, and declining GFR, represent very advanced diabetic glomerulopathy with especially prominent mesangial expansion. Mesangial expansion, by restricting glomerular capillary filtration surface and lumenal volume, stimulates compensatory mechanisms analogous to those resulting from a marked reduction in nephron number. These compensatory mechanisms involve alterations in glomerular hemodynamics designed to maintain glomerular filtration but which ultimately injure the kidney. These hemodynamic perturbations are not specific to diabetes but represent a final common pathway toward endstage renal failure that also characterizes the remnant kidney. This thesis concludes that the onset of clinical diabetic nephropathy augurs inevitable decline in kidney function, and that only studies and interventions exercised before clinical nephropathy develops can influence understanding and outcome of diabetic nephropathy.
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PMID:Diabetic nephropathy. A perspective. 640 Jun 68

Alterations in renal function and structure are found even at the onset of diabetes mellitus. Studies performed over the last decade now allow definition of a series of stages in the development of renal changes in diabetes. Such a classification may be useful both in clinical work and in research activities. Stage 1 is characterized by early hyperfunction and hypertrophy. These changes are found at diagnosis, before insulin treatment. Increased urinary albumin excretion, aggravated during physical exercise, is also a characteristic finding. Changes are at least partly reversible by insulin treatment. Stage 2 develops silently over many years and is characterized by morphologic lesions without signs of clinical disease. However, kidney function tests and morphometry on biopsy specimens reveal changes. The function is characterized by increased GFR. During good diabetes control, albumin excretion is normal; however, physical exercise unmasks changes in albuminuria not demonstrable in the resting situation. During poor diabetes control albumin excretion goes up both at rest and during exercise. A number of patients continue in stage 2 throughout their lives. Stage 3, incipient diabetic nephropathy, is the forerunner of overt diabetic nephropathy. Its main manifestation is abnormally elevated urinary albumin excretion, as measured by radioimmunoassay. A level higher than the values found in normal subjects but lower than in clinical disease is the main characteristic of this stage, which appeared to be between 15 and 300 micrograms/min in the baseline situation. A slow, gradual increase over the years is a prominent feature in this very decisive phase of renal disease in diabetes when blood pressure is rising. The increased rate in albumin excretion is higher in patients with increased blood pressure. GFR is still supranormal and antihypertensive treatment in this phase is under investigation, using the physical exercise test. Stage 4 is overt diabetic nephropathy, the classic entity characterized by persistent proteinuria (greater than 0.5 g/24 h). When the associated high blood pressure is left untreated, renal function (GFR) declines, the mean fall rate being around 1 ml/min/mo. Long-term antihypertensive treatment reduces the fall rate by about 60% and thus postpones uremia considerably. Stage 5 is end-stage renal failure with uremia due to diabetic nephropathy. As many as 25% of the population presently entering the end-stage renal failure programs in the United States are diabetic. Diabetic nephropathy and diabetic vasculopathy constitute a major medical problem in society today.
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PMID:The stages in diabetic renal disease. With emphasis on the stage of incipient diabetic nephropathy. 640 Jun 70

Glomerular filtration rate (GFR, single bolus 51Cr-EDTA technique), serum creatinine, proteinuria and arterial blood pressure have been measured prospectively in 14 young onset insulin-dependent diabetics selected by of persistent proteinuria (greater than 0.5 g/day) secondary to diabetic nephropathy. Twelve of the 14 patients had normal serum creatinine levels. None of the patients received antihypertensive treatment. During the mean observation period of 26 months (range 23 to 33 months) GFR decreased from 107 to 87 ml/min/1.73 m2 (p less than 0.001), serum creatinine remained unchanged: 107 and 112/mumol/l (NS), proteinuria increased from 1.8 to 3.3 g/day (p less than 0.001) and arterial blood pressure rose from 132/88 to 153/101 mmHg (p less than 0.001). Glomerular filtration rate decreased linearly with time (slope = -0.75, r = 0.99, p less than 0.001) by a mean of 0.75 ml/min/month (range 0.1 to 1.5 ml/min/month). The decrease in GFR did not correlate wih sex, age at onset, duration of diabetes, arterial blood pressure, proteinuria, insulin requirement, postprandial blood glucose or the initial GFR in each individual was constant, but varied considerably between patients. Increase in arterial blood pressure to a hypertensive level is an early feature of diabetic nephropathy in young insulin-dependent diabetics.
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PMID:A prospective study of glomerular filtration rate and arterial blood pressure in insulin-dependent diabetics with diabetic nephropathy. 701 39

The excretion rates of albumin, IgG and beta 2-microglobulin were studied in insulin-dependent diabetic patients with (Albustix positive) and without (Albustix negative) clinical proteinuria and in a group of nondiabetic controls. In patients negative for clinical proteinuria, the mean excretion rate of albumin and IgG was increased but that of beta 2-microglobulin was normal. HbA1, a measure of excess glycemia, was positively correlated with both albumin and IgG urinary excretion rates. Vigorous correction of glycemic control significantly reduced IgG excretion in nine patients. In patients positive for clinical proteinuria, albumin and IgG clearances were inversely correlated with GFR, the filtration of IgG increasing relatively more than that of albumin as GFR declined. A negative hyperbolic correlation was found between GFR and beta 2-micro-globulin excretion. In this group HbA1 was unrelated to excretion rates or clearances of albumin and IgG. In clinically proteinuric patients, long-term correction of hyperglycemia by continuous subcutaneous insulin infusion failed to check the increasing albumin and IgG filtration. The microproteinuria of diabetes is glomerular in origin, is influenced by prevailing glycemia, and is reversible by vigorous glycemic control. In the clinically proteinuric phase, by contrast, selectivity is progressively lost and, as GFR falls, proteinuria becomes of a mixed glomerular and tubular origin. There is no evident association with prevailing glycemia, and metabolic near-normalization dose not appear to affect progression over the period of observation considered. This study suggests that clinical proteinuria denotes the installation of a self-maintaining process, largely independent of the diabetic metabolic disturbance which gave rise to it. Prevention of clinical diabetic nephropathy by metabolic correction may be achievable only in the phase of early microproteinuria.
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PMID:Proteinuria in diabetes mellitus: role of spontaneous and experimental variation of glycemia. 705 May 9

Diabetic nephropathy is a progressive renal disease and represents a serious late complication of diabetes. There are familial clustering and huge ethnic differences in the occurrence of diabetic nephropathy, which point to a genetic predisposition. Diabetic nephropathy is defined by persistent albuminuria (albumin excretion rate [AER] > 300 mg/day), declining glomerular filtration rate and rising blood pressure. Several years of incipient nephropathy, characterized by worsening microalbuminuria (AER 30 to 300 mg/day or 20 to 200 micrograms/min), which is Albustix-negative and detectable by special assays only, are followed by established nephropathy. The natural history of nephropathy differs between insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. In IDDM, nephropathy develops in 30 to 40% of cases. The incidence peaks after 15 to 16 years of diabetes. In NIDDM, estimates of prevalence range from 15 to 20%, and nephropathy often supervenes after a shorter known duration of diabetes than in IDDM. GFR is often increased above normal (hyperfiltration) from the onset of IDDM due to increased renal blood flow, glomerular capillary hypertension and increased filtration surface. The glomeruli are hypertrophied and the kidneys enlarged. In both IDDM and NIDDM, GFR begins to decline irreversibly, when AER has risen to 100 to 300 mg/day at an average rate of 10 ml/min. per year. This is due to progressive reduction of the filtration surface area through mesangial expansion. Serum creatinine levels begin to rise when GFR falls below 50 ml/min, and then end-stage renal failure follows after an average of five years.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Diabetic nephropathy: significance of microalbuminuria and proteinuria in Type I and Type II diabetes mellitus]. 749 50

Initiation of antihypertensive treatment (AHT) in hypertensive insulin-dependent diabetic (IDDM) patients with diabetic nephropathy (DN) induces a faster initial (0 to 6 months) and a slower subsequent (6 months to end of observation) decline in GFR [delta GFR (ml/min/month) approximately 1.5 vs. 0.35]. Whether this initial phenomenon is reversible (hemodynamic) or irreversible (structural damage) after prolonged AHT is not known. To elucidate these mechanisms we investigated 42 hypertensive IDDM patients (16F/26M, age 40 +/- 7 years, mean +/- SD) with DN receiving AHT (angiotensin converting enzyme inhibition, N = 30) for 6 (2 to 15) years [median (range)]. GFR (ml/min/1.73 m2), arterial blood pressure (BP, mm Hg) and albuminuria (mg/24 hr) were measured the last day on AHT and one month after withdrawal of AHT. The measured variables were all significantly elevated after withdrawal of AHT: GFR [mean(SEM)] from 76(4) to 81(4) (P < 0.0001), BP [mean(SEM)] from 140/82 (2/1) to 151/89 (2/1) (P < 0.0005) and albuminuria [geometric mean (antilog SEM)] from 704 (1.2) to 1122 (1.2) (P < 0.0001). A correlation between relative rise in systolic blood pressure (delta Sys%) and relative change in GFR (delta GFR%) was found (r = 0.44, P < 0.005). Our results render some support of the hypothesis that the faster initial decline in GFR is due to a functional (hemodynamic) effect of AHT, which does not attenuate over time, while the subsequent slower decline reflects the beneficial effect on progression of diabetic nephropathy.
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PMID:Increased glomerular filtration rate after withdrawal of long-term antihypertensive treatment in diabetic nephropathy. 764 42

The effect was studied of blood pressure lowering treatment on renal failure and albuminuria (UAE) in patients with type I diabetes (IDDM) and imminent nephropathy as well as in patients with over diabetic nephropathy. The group of 24 patients with imminent nephropathy was subdivided: 1. twelve patients with borderline or overt hypertension with mean BP lowered not below 100 mmHg, and 2. twelve patients with BP within the normal limits, taking no hypotensive agents. In the other group of 12 patients with overt diabetic nephropathy hypertension was lowered below 105 mmHg and kept so for at least two years. All patients estimated their glycemia and glycosuria by themselves, ate 0.8 g protein/kg/24 h and about 100 mmol Na/24h. Under hospital conditions the following were estimated: albuminuria, glomerular filtration rate (51Cr EDTA) and effective renal blood flow (131I hippurate). The same examinations were repeated 1 year and 2 years later. The lowering of BP below 100 mmHg in patients with imminent diabetic nephropathy significantly lowered microalbuminuria without changing GFR, ERPF despite good or satisfactory compensation of diabetes. Maintaining BP below 105 mmHg for 2 years did not prevent the patients with overt nephropathy to develop progressive renal failure despite the rate of GFR deterioration and of the increase of albuminuria slowed down.
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PMID:[Effect of treatment of arterial hypertension on renal function in patients with imminent and overt diabetic nephropathy]. 773 1

The progression of diabetic nephropathy can be positively influenced by maintaining a low blood pressure level. This has been shown in studies with conventional antihypertensive treatment as well as with ACE inhibitors. Whether the latter group of drugs is more effective remains to be proven and was the aim of our study. In a prospective randomized study we compared the effects of ACE inhibition and beta-blockade on retarding progression of renal function in IDDM patients with an early stage of overt diabetic nephropathy. Twenty-nine patients were studied for 2 years, 15 were randomized for treatment with captopril and 14 for atenolol. Every 6 weeks blood pressure and urinary albumin and total protein excretion were measured. GFR was measured every 6 months as 51Cr-EDTA clearance. Baseline values for blood pressure, renal function and albuminuria were identical in the two groups. The effect of both drugs on blood pressure was not significantly different. In the captopril-treated patients MAP before and after 2 years was 110 +/- 3 (SEM) and 100 +/- 2 mm Hg, respectively and in the atenolol-treated patients 105 +/- 2 vs 101 +/- 2 mm Hg. Both drugs reduced albuminuria and total proteinuria to the same extent. With captopril albuminuria decreased from 1549 (989-2399) to 851 (537-1380) mg/24 h and proteinuria from 2.5 (1.6-3.8) to 1.2 (0.8-1.8) g/24 h. With atenolol albuminuria decreased from 933 (603-1445) to 676 (437-1047) mg/24 h and proteinuria from 1.5 (1.0-2.4) to 0.9 (0.6-1.5) g/24 h.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Captopril and atenolol are equally effective in retarding progression of diabetic nephropathy. Results of a 2-year prospective, randomized study. 774 19

Besides defining the appropriate doses of frusemide in uraemic patients, A. Heidland's contribution to the treatment of hypertension in chronic renal failure consisted in the following demonstrations: (1) In patients on chronic haemodialysis, calcium antagonists have a beneficial effect on their glucose intolerance and decreased plasma levels of 25OH vitamin D while their effect on blood lipids is neutral. (2) In 5/6 nephrectomized rats, captopril, verapamil, and metoprolol have the same protective effect on their GFR and tubular secretion of protons, at equal blood-pressure-lowering effect. (3) In rats with streptozotocin-induced diabetes, atrial natriuretic peptide does not play a role in their hyperfiltration. (4) Severe retinopathy is observed in patients with uraemic nephropathies at a much smaller elevation of their blood pressure than in patients with essential hypertension. This article reviews the following points: (1) The role of hypertension in the loss of renal function is convincingly demonstrated only in a few experimental models, and in man only in malignant hypertension and diabetic nephropathy but not in essential hypertension nor in non-diabetic nephropathy. However, preliminary results suggests that antihypertensive treatment may retard the progression of renal disease in normotensive patients (DBP <90 mmHg) with either microalbuminuric diabetes and normal renal function or non-diabetic uraemic nephropathy. (2) Only the ACE inhibitors have been proved to have a specific renal protective effect, independent of their diurnal blood-pressure-lowering effect, both in diabetic nephropathy and in non-diabetic uraemic nephropathy.
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PMID:Hypertension and progression of renal insufficiency. 807 21

Lithium is the best available marker of proximal tubular reabsorption of fluid. The first part of the present thesis reviews the background for the use of the lithium clearance (CLi) method. Micropuncture studies on proximal reabsorption of lithium, showed that CLi is a reasonably correct measure of end-proximal fluid delivery rate, even during osmotic diuresis. During severe salt restriction, distal reabsorption of lithium renders the CLi method inappropriate in animals, but this problem does probably not occur in humans. The major current issue is whether a quantitatively significant reabsorption of lithium occurs in the loop of Henle. Available evidence is in accord with the interpretation that it does not occur. The interpretation of results form CLi studies depends to a surprising degree on the investigators beliefs about renal physiology. In the evaluation of proximal tubular function, the relevant parameter is the absolute proximal reabsorption rate of fluid and sodium. In the evaluation of integrated distal tubular reabsorption of sodium, the relevant parameter is the fractional distal reabsorption rate of sodium. The fractional CLi does not give meaningful information, and calculated absolute distal reabsorption rate of sodium is inherently not suited to detect modest changes in distal reabsorption leading to large changes in sodium excretion. Results from the use of the CLi method in relation to diabetes are reviewed in the second section. Even in IDDM patients with early diabetic nephropathy, the proximal reabsorption rate is elevated, resulting in a normal CLi despite glomerular hyperfiltration. Overnight euglycemia did not change GFR in IDDM patients, but during maintained euglycemia, GFR was normalized. A few hours of hyperglycemia prevented the decline in GFR, whereas CLi was unchanged. Thus hyperglycemia produced changes in renal function similar to those observed previously, but the time-course of the effect of euglycemia on kidney function is delayed. Plasma levels of atrial natriuretic peptide, renin and glucagon were not importantly affected by plasma glucose. In NIDDM patients CLi was normal, despite slight hyperfiltration, although this observation must be confirmed in a study with larger sample size. Prompted by the clinical observation of a marked decline in the GFR induced by carbonic anhydrase inhibitors, we studied the renal effects of acetazolamide in a controlled study.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Lithium clearance in the evaluation of segmental renal tubular reabsorption of sodium and water in diabetes mellitus. 818 64


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