Value of blood pressure self-monitoring as a predictor of progression of diabetic nephropathy.

OBJECTIVE: To determine the impact of self-monitoring of blood pressure values (BP(S)) as compared with office blood pressure measurements (BP(O)) on the progression of diabetic nephropathy. DESIGN: Long-term, follow-up cohort study. SUBJECTS AND METHODS: Hypertensive, type 1 diabetic patients with overt diabetic nephropathy were investigated. Patients initially participated in a hypertension treatment and teaching programme including extensive advice on blood pressure self-monitoring. Self-monitoring and office blood pressure values were continuously assessed during the entire follow-up period. Progression of diabetic nephropathy over the study period was individually assessed as the mean decline of glomerular filtration rate (GFR) per patient per year. Baseline and follow-up parameters were included in stepwise multiple regression analyses with the decline of GFR per year as the dependent variable. RESULTS: Seventy-seven type 1 diabetic patients (37 women, 40 men) were followed for a mean period of 6.2 +/- 2.8 years (mean +/- SD; range 2-12) resulting in a total of 481 patient-years. During the follow-up period, mean BP(O) decreased from 166/95 at baseline to 154/89 mmHg during follow-up, and mean BP(S) fell from 159/93 to 138/83 mmHg. The mean decline of GFR was 4.1 +/- 5.6 ml/min per year. Loss of kidney function was significantly correlated with proteinuria, blood pressure and glycosylated haemoglobin values. In the multiple regression analyses, BP(S) predicted the loss of renal function better than BP(O) (R2 = 0.52 versus 0.42). The simple correlation between BP(S) and GFR decline was higher compared to BP(O) and GFR (r = -0.42; P < 0.0001 versus -0.33; P < 0.004). CONCLUSION: Blood pressure self-monitoring values are a better predictor of progression of diabetic nephropathy when compared with office blood pressure measurements.     

Natural course of kidney function in Type 2 diabetic patients with diabetic nephropathy.

AIMS: To determine the natural course of kidney function and to evaluate the impact of putative progression promoters in Caucasian Type 2 diabetes mellitus (DM) patients with diabetic nephropathy who had never received any antihypertensive treatment. METHODS: A long-term observational study of 13 normotensive to borderline hypertensive Type 2 DM patients with diabetic nephropathy. Glomerular filtration rate (GFR) was measured approximately every year (51Cr-EDTA plasma clearance technique). Albuminuria, blood pressure (BP) and haemoglobin A1c (HbA1c) was determined 2-4 times per year and serum cholesterol every second year. RESULTS: The patients (12 males/one female), age 56+/-9 (mean +/- SD) years, with a known duration of diabetes of 10+/-6 years, were followed for 55 (24-105) (median (range)) months. GFR decreased from 104 (50-126) to 80 (39-112) ml x min(-1) x 1.73 m(-2) (P = 0.002) with a median rate of decline of 4.5 (-0.4 to 12) ml x min(-1) x year(-1). During follow-up, albuminuria rose from 494 (301-1868) to 908 (108-2169) mg/24 h (P = 0.25), while BP, HbA1c and serum cholesterol remained essentially unchanged. In univariate analysis the rate of decline in GFR did not correlate significantly with neither baseline nor mean values during follow-up of BP, albuminuria, HbA1c and serum cholesterol. CONCLUSIONS: Our study suggests that normotensive to borderline hypertensive Type 2 DM patients with diabetic nephropathy have a rather slow decline in kidney function, but we did not unravel the putative progression promoters responsible for the variation in rate of decline in GFR.     

The role of glycemia and blood pressure control on the rate of decline in glomerular filtration rate in Vietnamese type 2 diabetes patients

The rate of decline in glomerular filtration rate (?↓GFR), commonly used to evaluate the progression of chronic kidney disease (CKD), varies considerably among type 2 diabetes subjects. The determinants of the variability especially hyperglycemia and hypertension are not consistent. We present a retrospective cohort study [450 out of 536 patients with type 2 diabetes who did not have renal insufficiency at baseline (estimated GFR?≥?60 ml/min/1.73 m²)]. We examined factors affecting progression of ?↓GFR as an endpoint using linear regression analysis. The mean ?↓GFR was 2.3 (SD 2.9) mL/min/1.73 m²/year. Univariate analysis showed that this was associated with mean HbA1c (P?=?0.004), mean systolic blood pressure (BP) (P?<?0.001), and mean pulse pressure (P?<?0.001). Hazard ratio (HR) of the appearance of renal insufficiency was significantly higher in the group with mean systolic BP?≥?130 mmHg (HR?=?3.0, P?<?0.001) and mean pulse pressure ≥ 50 mmHg (HR?=?3.7, P?<?0.001). In subjects with type 2 diabetes, glycemia and BP control play an important role on slowing the rate of decline in kidney function. Higher systolic BP and pulse pressure, but not diastolic BP, are significantly associated with increased ?↓GFR.     

The relationship between magnitude of proteinuria reduction and risk of end-stage renal disease: results of the African American study of kidney disease and hypertension

BACKGROUND: The magnitude of proteinuria is associated with a graded increase in the risk of progression to end-stage renal disease and cardiovascular events. The objective of this study was to relate baseline and early changes in proteinuria and glomerular filtration rate (GFR) to long-term progression of hypertensive nondiabetic kidney disease. METHODS: Post hoc analysis of a randomized 3 x 2 factorial trial. A total of 1094 African Americans with hypertensive renal disease (GFR, 20-65 mL/min per 1.73 m(2)) were followed up for a median of 3.8 years. Participants were randomized to a mean arterial pressure goal of 102 to 107 mm Hg (usual) or 92 mm Hg or less (lower) and to initial treatment with a beta-blocker (metoprolol), an angiotensin-converting enzyme inhibitor (ramipril), or a dihydropyridine calcium channel blocker (amlodipine) RESULTS: Baseline proteinuria and GFR predicted the rgate of GFR decline. For each 10-mL/min per 1.73 m(2) lower baseline GFR, an associated mean +/- SE 0.38 +/- 0.08-mL/min per 1.73 m(2) per year greater mean GFR decline occurred, and for each 2-fold higher proteinuria level, a mean +/- SE 0.54 +/- 0.05-mL/min per 1.73 m(2) per year faster GFR decline was observed (P < .001 for both). In multivariate analysis, the effect of baseline proteinuria GFR decline persisted. Initial change in proteinuria from baseline to 6 months predicted subsequent progression, with this relationship extending to participants with baseline urinary protein levels less than 300 mg/d. CONCLUSIONS: The change in the level of proteinuria is a predictor of subsequent progression of hypertensive kidney disease at a given GFR. A prospective trial is needed to confirm this observation.     

Inverse relationship between ambulatory arterial stiffness index and glomerular filtration rate in arterial hypertension

BACKGROUND: Arterial stiffness and mild-to-moderate renal dysfunction are predictors of cardiovascular (CV) morbidity and mortality. Recently, the ambulatory arterial stiffness index (AASI) has been proposed as a surrogate index of arterial stiffness. It has been associated with an enhanced risk of stroke. The aim of our study was to assess the relationship between AASI and glomerular filtration rate (GFR) in a group of hypertensive patients with no CV complications. METHODS: A total of 143 untreated hypertensive subjects (mean age: 44 +/- 12 years; men 57%), with serum creatinine <1.5 mg/dl, were enrolled. AASI was calculated as one minus the regression slope of diastolic on systolic blood pressure (BP) obtained by individual 24-h BP recordings. GFR was computed from the scintigraphic determination of the technetium-99m diethylenetriaminepentaacetic acid uptake within the kidneys, by the Gates' method. RESULTS: Hypertensive patients with AASI above the median value (n = 71) had lower GFR than those with AASI below the median (n = 72) (98.3 +/- 31 vs. 122.4 +/- 32 ml/min/1.73 m(2); P < 0.001). This difference held even after adjustment for age and gender. The linear regression analysis disclosed a significant inverse correlation between GFR and AASI (r = -0.30; P < 0.001), that was replicated (beta = -0.19; P = 0.02) in a multiple regression model including, as independent variables (besides AASI), age, gender, high-density lipoprotein cholesterol, body mass index, 24-h pulse pressure (PP) and nocturnal reduction in BP. CONCLUSIONS: AASI is inversely related to GFR in arterial hypertension. This may help to explain the increased CV risk associated with mild-to-moderate renal dysfunction.     

The effect of fenoldopam on renal haemodynamics and natriuresis in chronic renal failure

The effect of oral administration of fenoldopam, a dopamine-1 receptor agonist, on blood pressure, renal haemodynamics and natriuresis was studied in 12 patients with chronic renal insufficiency. In addition, the effect of administering a low intravenous dose of fenoldopam on top of the oral dose was compared with the effect of the same intravenous dose given immediately before oral fenoldopam. Oral administration of fenoldopam (50 mg t.i.d. for 3 +/- 1 days followed by 100 mg t.i.d. for 8 +/- 1 days) induced a significant fall in blood pressure (median MAP from 107 to 101 mm Hg). Compared to baseline values, body weight, effective renal plasma flow (ERPF), glomerular filtration rate (GFR) and fractional sodium excretion remained unchanged. Infusion of fenoldopam (0.05-0.1 micrograms/kg/min) on day 1 led to a significant fall in blood pressure (median mean arterial pressure from 107.0 to 98.5 mm Hg), and a significant rise in effective renal plasma flow (median ERPF from 132 to 146 ml/min/1.73 m2). Median fractional sodium excretion increased significantly from 2.1 to 3.3%. GFR, filtration fraction and plasma aldosterone concentration did not change. No relationship was found between the fenoldopam-induced changes in ERPF and natriuresis, nor between baseline GFR or ERPF and fenoldopam-induced urinary sodium loss. Infusion of fenoldopam while patients were on oral fenoldopam had no effect on blood pressure, ERPF or GFR. However, again natriuresis was induced, which did not differ significantly from the fenoldopam-induced natriuresis on day 1. We conclude that oral fenoldopam has a moderate blood pressure lowering effect in patients with chronic renal insufficiency, but exerts no effect on ERPF or GFR. Secondly, a fenoldopam-induced natriuresis does not appear to be related to changes in ERPF or aldosterone secretion.     

Left ventricular mass and glomerular hyperfiltration in essential hypertension

OBJECTIVE: to assess the early involvement to target organs in never treated essential hypertensives (HT). METHODS: effective renal plasma flow (ERPF, 131I-Hippurate) and glomerular filtration rate (GFR, 99mTc-DTPA) were estimated in 80 mild HT. Left ventricular mass (LVM, M-mode echocardiography), sodium intake (24h UNaV) and urinary kallikrein (Kall) were also measured. Hyperfiltering patients (HF, GFR = 155 +/- 3 ml/min: 1.73 m2, n = 21) were defined by comparison with age-matched normotensive. HF patients were pair-matched for age, sex and blood pressure level with normofiltering hypertensives (NF, GFR = 112 +/- 3, n = 21). RESULTS: are expressed as mean +/- sem [table: see text] CONCLUSION: These results suggest that a high Na intake is associated with hyperfiltration and higher LVMI in subjects with never treated essential hypertension of short duration.     

Incidence of hypertension in individuals with different blood pressure salt-sensitivity: results of a 15-year follow-up study

OBJECTIVE: To evaluate the incidence of hypertension and the rate of decline in renal function in a sample of 47 Olivetti Heart Study (OHS) participants whose blood pressure (BP) salt-sensitivity and renal tubular sodium handling had been assessed in 1987-88. METHODS: During the 2002-04 OHS follow-up examination, medical history, physical examination and blood and urine sampling were performed in 36 of the 47 participants to the baseline study (age 60 +/- 6 years; average follow-up = 15.1 +/- 0.6 years). The renal length was measured in 23 participants by kidney ultrasonography. Based on the baseline salt-sensitivity evaluation, the subjects were classified into a lower salt-sensitivity (LSS, n = 20) and a higher salt-sensitivity group (HSS, n = 16). RESULTS: In comparison with the LSS group, HSS participants had a significantly higher incidence of hypertension (87.5 versus 50.0%, P = 0.02), a higher glomerular filtration rate (median, first to fourth quartile: 81.9, 72.3-95.2 versus 72.3, 59.9-81.2 ml/min; P = 0.03) and greater kidney length (median, first to fourth quartile: 68.2, 63.3-72.1 versus 61.9, 58.7-62.7 mm/m of height; P = 0.003). The incidence of hypertension remained significantly higher in HSS individuals after adjustment for age, intercurrent changes in body mass index and baseline blood pressure on low sodium diet (P = 0.04). CONCLUSION: Our findings indicate that individuals with higher BP salt-sensitivity have a higher rate of incident hypertension and suggest an altered renal tubular sodium handling involving a trend to increased glomerular filtration rate and blood pressure over time as a possible mechanism.     

Self-measured systolic blood pressure in the morning is a strong indicator of decline of renal function in hypertensive patients with non-diabetic chronic renal insufficiency

While blood pressure is a recognized major determinant of renal function deterioration, the role of self blood pressure measurement (BPM) in predicting the loss of renal function in hypertensive patients with chronic renal insufficiency (CRI) has not been adequately addressed. One hundred and thirteen patients (F/M: 46/67; 56 +/- 1 years) with CRI (mean serum creatinine: 1.87 +/- 0.08; range: 1.4 to 3.5 mg/dl; average urinary protein excretion: 1.2 +/- 0.2 g/24 hrs.) were followed for 3 years. The record of renal biopsy revealed that 74 patients had IgA nephropathy, 16 had chronic glomerulonephritis, and 6 had membranous nephropathy, while 17, unbiopsied patients had underlying renal disease of unknown origin. Self BPM were made at regular intervals throughout the course of the study. All recorded blood pressures were included in a stepwise multiple regression analysis in which the decline in GFR per year was the dependent variable. Patients were primarily treated with a combination of amlodipine (5 to 20 mg daily), a calcium antagonist, and benazepril (2.5 to 5 mg daily), an ACE inhibitor in an effort to reduce their blood pressure at the office to < 130/85 mmHg. The simple correlation between blood pressures (i.e., office, home morning and home evening) and the decline in GFR were all statistically significant. The correlation coefficients of determination for this model were as follows: r = 0.64 for home morning SBP; 0.43 for office SBP; 0.39 for office DBP; and 0.38 for home morning DBP. The level of urinary protein excretion did not correlate with the decline in GFR. These data suggest that self BPM improves prognostic ability in hypertensive patients with CRI.     

Impact of age on left ventricular hypertrophy regression during antihypertensive treatment with losartan or atenolol (the LIFE study)

To assess the influence of age on changes in left ventricular (LV) mass and geometry during antihypertensive treatment, we related age to clinical and echocardiographic findings before and after 4 years of antihypertensive treatment in a subset of 560 hypertensive patients without known concurrent disease in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, which randomized patients to blinded losartan- or atenolol-based treatment. Patients >/=65 years (older group) included more women and patients with isolated systolic hypertension or albuminuria (all P<0.05). Compared to patients <65 years, older patients had higher pulse pressure, LV mass, and prevalence of concentric hypertrophy at baseline (78 vs 69 mmHg, 234 vs 224 g, and 28 vs 16%, respectively, all P<0.01), while the mean blood pressure did not differ. Over 4 years, reductions in LV mass and the mean blood pressure were similar in both groups, but older patients more often had residual hypertrophy (31 vs 15%, P<0.001) with a preponderance of eccentric geometry. In multivariate analysis of 4-year change in LV mass controlling for baseline mass, larger hypertrophy reduction was associated with losartan treatment, while age, gender, body mass index, and 4-year change in pulse pressure and albuminuria did not enter (Multiple R (2)=0.40, P<0.001). Thus, in up-to-80-year-old hypertensive patients with left ventricular hypertrophy, age did not significantly attenuate hypertrophy reduction during antihypertensive treatment, although residual hypertrophy was more prevalent in older patients as a consequence of higher initial LV mass.     

Decreased cardiac output, venous congestion and the association with renal impairment in patients with cardiac dysfunction

BACKGROUND: Renal failure in heart failure is related to decreased cardiac output. However, little is known about its association with venous congestion. AIMS: To investigate the relationship between venous congestion and glomerular filtration rate (GFR) in patients with cardiac dysfunction. METHODS AND RESULTS: Right atrial pressure (RAP) and cardiac index (CI) were determined by right heart catheterisation in 51 patients with cardiac dysfunction, secondary to pulmonary hypertension. GFR and renal blood flow (RBF) were measured as (125)I-Iothalamate and (131)I-Hippuran clearances, respectively. Mean age was 40+/-11 years and 69% of patients were female. GFR was 73+/-19 ml/min/1.73 m2 with a CI of 2.1+/-0.7 l/min/m2. In multivariate analysis, RBF (r=0.664, p<0.001) and RAP (r=- 0.367, p=0.020) were independently associated with GFR. In patients in the lower ranges of RBF, venous congestion was an important determinant of renal function. CONCLUSION: RBF is the main factor determining GFR in patients with cardiac dysfunction. Venous congestion, characterised by an increased RAP, adjusted for RBF is also related to GFR. Treatment to preserve GFR should not only focus on improvement of renal perfusion, but also on decreasing venous congestion.     

Glomerular filtration rate changes in normoalbuminuric and microalbuminuric Type 2 diabetic patients and normal individuals A 10-year follow-up

AIM: To analyze the changes in the glomerular filtration rate (GFR) in a cohort of normoalbuminuric Type 2 diabetic (DM 2) patients and nondiabetic individuals. METHODS: Sixty-five normoalbuminuric DM 2 patients [urinary albumin excretion rate (UAER) <20 microg/min] and 44 nondiabetic individuals recruited at baseline were followed for a mean period of 10 +/- 1 years. In addition to conventional clinical and metabolic variables, GFR ((51)Cr-EDTA technique) and UAER (immunoturbidimetric method) measurements were performed at baseline and at follow-up. We also evaluated the presence of diabetic retinopathy, hypertension, and cardiovascular disease. Multiple linear regression was performed to assess variables independently associated with GFR evolution in patients with Type 2 diabetes. RESULTS: Fifty DM 2 patients and 32 nondiabetic individuals were included in the follow-up evaluation. Fourteen out of the 50 patients with Type 2 diabetes developed microalbuminuria. They presented a faster GFR decline (-0.39+/-0.24 ml/min/month; ANOVA, P=.0013) than did persistently normoalbuminuric (-0.16+/-0.16 ml/min/month) and nondiabetic individuals (-0.13+/-0.14 ml/min/month). Multiple linear regression analysis disclosed baseline fasting plasma glucose (FPG) along with the development of microalbuminuria as factors significantly related to a higher GFR decline. CONCLUSIONS: Persistently normoalbuminuric patients and normal individuals presented a similar degree of GFR reduction related to the aging process. The slope was significantly enhanced in patients who developed microalbuminuria and was influenced by worse baseline glucose control.     

Does albuminuria predict cardiovascular outcome on treatment with losartan versus atenolol in hypertension with left ventricular hypertrophy? A LIFE substudy

OBJECTIVES: To examine a possible relationship between baseline albuminuria and effect of losartan versus atenolol on cardiovascular (CV) events in hypertensive patients with left ventricular hypertrophy, the effect of losartan versus atenolol on albuminuria, and whether the benefits of losartan versus atenolol could be explained by influence of losartan on albuminuria. DESIGN: Double-blind, randomized, controlled trial of 4.8 years. SETTING: Out-patient setting. PATIENTS: A total of 8206 with hypertension and left ventricular hypertrophy. INTERVENTIONS: Losartan or atenolol, supplemented with diuretics and/or calcium antagonists to reach blood pressure < 140/90 mmHg MAIN OUTCOME MEASURES: The urine albumin/creatinine ratio, and the primary composite endpoint (CEP) of CV death, myocardial infarction, and stroke. RESULTS: The blood pressure was reduced similarly on losartan (30.2/16.6 mmHg) versus atenolol (29.1/16.8 mmHg). The risk of a primary CEP increased linearly from the lowest to the highest decile of baseline albuminuria. The benefits of losartan versus atenolol for the primary CEP and for stroke tended to be more pronounced among patients above the median value for baseline albuminuria (urine albumin/creatinine ratio, 1.28 mg/mmol). The decrease in albuminuria was significantly greater with losartan versus atenolol throughout the study (a decrease from baseline to year 2 of 33% losartan versus 25% atenolol). One-fifth of the difference in favor of losartan on the primary CEP was explained by the greater reduction in albuminuria on losartan. CONCLUSIONS: Baseline albuminuria is a powerful risk factor for CV events. Baseline albuminuria did not identify the group of patients with greatest benefit on losartan versus atenolol in LIFE. Reduction in albuminuria explained one-fifth of the benefits of losartan versus atenolol.     

The efficacy and tolerability of fosinopril in Chinese type 2 diabetic patients with moderate renal insufficiency

BACKGROUND: The renoprotective effect of angiotensin II antagonists has been demonstrated in type 2 diabetic patients with nephropathy but similar data on angiotensin-converting enzyme (ACE) inhibitors are limited. We examined the efficacy and tolerability of fosinopril, an ACE inhibitor with dual hepatic and renal clearance, in 38 type 2 diabetic patients with moderate renal impairment (plasma creatinine 130-300 micromol/l) over a 2-year period. METHODS: This was a single-centre, randomized, double-blinded, placebo-controlled trial comparing fosinopril 20 mg daily vs. placebo in addition to conventional antihypertensive treatment over a 2-year period. The primary endpoints were the rate of change and the percentage change in both 24-h urinary albumin excretion (UAE) and creatinine clearance (CrCl). RESULTS: The mean age of the patients was 65 +/- 6 years (range 47-76 years, median 66 years) and plasma creatinine 190 +/- 49 micromol/l. For similar blood pressure control, the percentage change of UAE in patients with microalbuminuria was greater in the fosinopril than the placebo group (-24.2 +/- 28.8 vs. 11.6 +/- 42.1%, p = 0.003 after adjustment for baseline covariates). In the fosinopril group, the rate of change of endogenous CrCl was slower than the placebo group (-0.07 +/- 0.19 vs. -0.24 +/- 0.35 ml/min/week, p = 0.026). The incidence of adverse events was similar between the two groups. CONCLUSIONS: Fosinopril treatment reduced albuminuria and rate of decline in renal function in type 2 diabetic patients with moderate renal insufficiency and did not increase the incidence of adverse events.     

老年高血压患者动态血压与肾功能损害

目的:探讨老年高血压患者动态血压与慢性肾功能损害的关系。方法:对已服降压药物控制血压的老年高血压患者测定24h动态血压,以血清肌酐(SCr)代入简化MDRD公式估算肾小球滤过率(GFR),以GFR60mL·min-1·1.73m-2设为肾功能不全组(男性40例,女性5例),与GFR≥60mL·min-1·1.73m-2、年龄、性别匹配的45例比较。结果:1.2组患者年龄相近,(77.0±6.1)岁vs(76.9±5.5)岁,P0.05;SCr、GFR差异有统计学意义。2.90例中非勺型血压71例占78.9%,2组比较差异无统计学意义,38/45vs33/45,χ2=1.668,P0.05。3.肾功能不全组平均舒张压(DBP)、日间舒张压(dDBP)、最高舒张压(DBPmax)、舒张压波动幅度(△DBP=最高舒张压-最低舒张压)明显低于对照组,平均脉压(PP)及夜间脉压(nPP)明显高于对照组,均P0.05。Logistic多元回归分析显示,△DBP降低与nPP增加为肾功能不全的独立危险因素,OR值分别为0.941(95%CI0.894～0.991)和1.043(95%CI1.006～1.081)。4.GFR与DBPmax、△DBP正相关,与PP、nPP、nSBP负相关,在控制年龄因素后相关性依然具有统计学意义,均P0.05;△DBP与DBPmax显著正相关,r=0.820,P0.01,而与最低舒张压(DBPmin)无相关性。结论:合并有肾功能不全的老年高血压患者较对照人群明显有增加的PP和降低的DBP水平。其nPP的增加和△DBP的降低与肾功能损害有关。降压治疗的老年患者,PP(尤其nPP)的增加和△DBP的降低可能对GFR下降存在不利影响。     

Early alteration in glomerular reserve in humans at genetic risk of essential hypertension: mechanisms and consequences

Essential hypertension has a familial predisposition, but the phenotype of elevated blood pressure has delayed penetrance. Because the kidney is a crucial determinant of blood pressure homeostasis, we studied early glomerular alterations in still-normotensive young subjects at genetic risk of hypertension. Thirty-nine normotensive adults (mean age 29 to 31 years), stratified by genetic risk (parental family history [FH]) of hypertension (26 with positive FH [FH+], 13 with negative FH [FH-]), underwent intravenous infusion of mixed amino acids. Before and during amino acid administration, we measured glomerular filtration rate (GFR), putative second messengers of amino acids (nitric oxide [NO.] metabolites and cGMP), serum insulin and amino acid concentrations, and the FE(Li)+ as an index of renal proximal tubular reabsorption. The FH+ group had a blunted GFR rise in response to amino acids (2.43+/-8.16% versus 31.0+/-13.4% rise, P:=0.0126). The amino acid-induced change in GFR correlated (r=0.786, P:<0.01) with the change in urinary NO. metabolite excretion; a diminished rise in urinary NO. metabolite excretion in the FH+ group (P:=0.0105) suggested a biochemical mechanism for the different GFR responses between FH groups: a relative inability to convert arginine to NO. The FH+ group had a far lower initial cGMP excretion at baseline (261+/-21.1 versus 579+/-84.9 nmol. h(-1)/1.73 m(2), P:=0.001), although cGMP did not change during the amino acid infusion (P:=0.703). FH status, baseline GFR, and baseline serum insulin jointly predicted GFR response to amino acids (P:=0.0013), accounting for approximately 45% of the variance in GFR response. Decline in FE(Li)+, an inverse index of proximal tubular reabsorption, paralleled increase in GFR (r=-0.506, P:=0.01), suggesting differences in proximal tubular reabsorption during amino acids between the FH groups. GFR response to amino acid infusion was blunted in the FH+ group despite significantly higher serum concentrations of 6 amino acids (arginine, isoleucine, leucine, methionine, phenylalanine, and valine) in the FH+ group, suggesting a novel form of insulin resistance (to the amino acid-translocating action of insulin) in FH+ subjects. We conclude that blunted glomerular filtration reserve in response to amino acids is an early-penetrance phenotype seen even in still-normotensive subjects at genetic risk of hypertension and is linked to impaired formation of NO. in the kidney. Corresponding changes in GFR and fractional excretion of Li(+) suggest that altered proximal tubular reabsorption after amino acids is an early pathophysiologic mechanism. Resistance to the amino acid-translocating actions of insulin may play a role in the biological response to amino acids in this setting. This glomerular reserve phenotype may be useful in genetic studies of renal traits preceding or predisposing to hypertension.     

Association of impaired diurnal blood pressure variation with a subsequent decline in glomerular filtration rate

BACKGROUND: Most healthy people exhibit a decrease in systolic blood pressure (SBP) at night. A drop of less than 10% from mean daytime values (nondipping) is associated with chronic kidney disease, insulin resistance, and cardiovascular events. Whether nondipping precedes a decline in renal function remains unclear. We hypothesized that nondipping would predict a decline in the glomerular filtration rate (GFR) over time. METHODS: Consecutive patients referred for ambulatory blood pressure monitoring were included in our retrospective cohort if they had a serum creatinine level noted at the time of their ambulatory blood pressure recording and a follow-up creatinine level recorded at least 1 year later. Mean day and night SBPs were compared (nighttime SBP-daytime [corrected] SBP ratio). We defined nondipping as a nighttime [corrected] SBP-daytime [corrected] SBP ratio higher than 0.90. The GFR was calculated using the Modification of Diet in Renal Disease 4-variable equation. RESULTS: Of 322 patients included, 137 were dippers and 185 were nondippers; their mean baseline GFRs were 80.5 mL/min per 1.73 m(2) and 76.4 mL/min per 1.73 m(2), respectively. During a median follow-up of 3.2 years, the GFRs remained stable among dippers (mean change, 1.3%) but declined among nondippers (mean change, -15.9%) (P<.001). The creatinine levels increased by more than 50% in 2 dippers (1.5%) and in 32 nondippers (17.3%) (P<.001). These findings persisted after adjustment for other predictors of GFR decline. CONCLUSION: Blunted diurnal blood pressure variation is associated with a subsequent deterioration in renal function that is independent of SBP load and other risk factors for renal impairment.     

Birth weight – a risk factor for progression in diabetic nephropathy?

OBJECTIVES: Intrauterine growth retardation, as seen in individuals with low weight at birth, may give rise to a reduction in nephron number. Oligonephropathy has been linked to hypertension and renal disease in adult life. We tested the concept that low weight at birth acts as a risk factor for progression of diabetic nephropathy. DESIGN AND SUBJECTS: We performed an observational follow-up study of 161 (97 men) type 1 diabetic patients with diabetic nephropathy [mean age (SD): 35 (11) years, mean duration of diabetes: 22 (8) years]. All patients had been followed for at least 3 years [median (range): 8 (3-20)] with at least three measurements [9 (3-31)] of glomerular filtration rate (GFR) (51Cr-EDTA). Information about birth size was obtained from midwife registrations. SETTINGS: Steno Diabetes Center, a tertiary referral centre. MAIN OUTCOME MEASURES: Loss of kidney function according to birth weight and weight/length ratio at birth. RESULTS: There was no correlation in univariate analysis between birth weight or weight/length ratio and rate of decline in GFR, neither in men nor in women. Furthermore, the 27 patients with birth weights below the 20th centile had a rate of decline in GFR [median (range)] similar to the 134 patients above: 2.6 (-4.7; 9.6) vs. 3.4 (-2.3; 19.3) mL min(-1) year(-1), respectively (NS). A multiple regression analysis revealed that albuminuria, arterial blood pressure, and haemoglobin A1C during follow-up showed a significant correlation with the decline in GFR [R2 (adjusted) = 0.34], whereas birth weight and birth weight/length ratio did not. CONCLUSIONS: Our study does not suggest that weight at birth is associated with progression of established diabetic nephropathy in type 1 diabetic patients, whilst several other potential modifiable risk factors were identified.     

Correlates of pulse pressure reduction during antihypertensive treatment (losartan or atenolol) in hypertensive patients with electrocardiographic left ventricular hypertrophy (the LIFE study)

In hypertensive patients, pulse pressure has been related to hypertension-induced target organ damage and risk of cardiovascular events. However, correlates of pulse pressure reduction during antihypertensive treatment have been less extensively investigated. We related pulse pressure changes to clinical and echocardiographic findings before and after 2 years of antihypertensive treatment in 767 patients aged 55 to 80 years (mean 66) in the Losartan Intervention For End point reduction in hypertension study. Over 2 years, blood pressure and pulse pressure were reduced from 173/98 to 147/84 mm Hg and from 75 to 63 mm Hg, respectively, both p <0.001. In linear multivariate analysis controlling for initial pulse pressure, 2-year reduction in pulse pressure correlated negatively with age and concomitant diabetes mellitus, and positively with body height and 2-year reduction in mean blood pressure (multiple R(2) = 0.42, p <0.01). When dividing the study population into 2 groups using a prognostically validated partition for pulse pressure, patients with pulse pressure > or =63 mm Hg after 2 years of antihypertensive treatment (n = 349) were older and shorter, included more women and patients with isolated systolic hypertension, diabetes mellitus, albuminuria, and echocardiographic left ventricular hypertrophy at baseline, and also had a smaller decrease in mean blood pressure and the urinary albumin/creatinine ratio over 2 years (all p <0.05). Thus, in hypertensive patients with electrocardiographic left ventricular hypertrophy, older age, less reduction in mean blood pressure, concomitant diabetes mellitus, and shorter stature are associated with attenuated pulse pressure reduction during antihypertensive treatment.     

Reduced glomerular filtration rate and cardiovascular damage in diabetes: a key role for abnormal albuminuria

There is general agreement that a fall rate in glomerular filtration rate (GFR) is the principal endpoint in diabetics with renal disease, and that abnormal albuminuria (including microalbuminuria) is an important intermediate end-point. The relative roles of blood pressure (BP) elevation and abnormal albuminuria in the prediction and genesis of renal disease are a matter of debate, and are further analysed in this paper. New studies show that neither genetic predisposition to hypertension (parental BP) nor parental abnormal albuminuria can be used to predict renal disease in patients with type 1 (insulin-dependent) diabetes. However, parental predisposition to proteinuria seems to be important to certain types of patients with type 2 (non-insulin-dependent) diabetes. Cross-sectional as well as follow-up studies document that GFR is generally well preserved in microalbuminuria (in both type 1 and type 2 patients), while the transition to clinical proteinuria is associated with a decline in GFR. Thus, prevention of overt proteinuria is important in clinical trials in microalbuminuric patients. In type 1 diabetes clear ultrastructural changes have been documented with microalbuminuria and a good correlation between abnormal albuminuria and structural damage is seen. Structural damage in normo- and microalbuminuric patients correlates poorly with BP. New studies in type 1 diabetes document that microalbuminuria (but not elevated BP) predicts not only clinical diabetic nephropathy but also end-stage renal failure and mortality. In type 2 diabetes microalbuminuria is the strongest predictor of mortality, whereas BP elevation is not a predictor. Several studies now document that antihypertensive treatment, especially with inhibitors of angiotensin converting enzyme, is able to reverse or reduce abnormal albuminuria, even in non-hypertensive type 1 patients, and possibly preserve GFR. Therefore, microalbuminuria may be the main indicator for starting antihypertensive treatment in these patients. With respect to organ damage in the retina, abnormal albuminuria is an important indicator of the risk of severe diabetic retinopathy. BP elevation seems not to be an initiating factor, but rather aggravates established retinopathy. Left ventricular hypertrophy has a stronger correlation with BP elevation than normoalbuminuria, suggesting that left ventricular hypertrophy is at least partially a phenomenon secondary to elevated BP in diabetic patients with abnormal albuminuria. Generally, abnormal albuminuria is a strong indicator of cardiovascular renal damage in diabetic patients and in most organs is a stronger factor than elevated BP.