Early diastolic strain rate and its associations with estimated glomerular filtration rate and albuminuria

Background

The ratio of early diastolic inflow to early diastolic strain rate, E/e'sr, is a novel echocardiographic measure, which has been shown to correlate better with left ventricular (LV) filling pressures than the conventionally used measure, E/e' (1). Additionally, E/e'sr has demonstrated prognostic value in various patient populations (2). Patients with chronic kidney disease (CKD) suffer frequently of diastolic dysfunction and elevated filling pressures (3). We wanted to investigate, how E/e'sr associates with two central measures of kidney function: estimated glomerular filtration rate, eGFR, and urine albumin creatinine ratio, UACR.

Methods

We enrolled a cohort of 825 ambulatory patients with CKD at the Departments of Nephrology of two university hospitals. Participants were examined with echocardiography including tissue doppler imaging. Two-dimensional speckle strain analysis was performed in all three apical standard projections. LV mass index (LVMI), E/e' and global longitudinal strain (GLS) were determined according to guidelines (4,5). Global early diastolic strain rate, e'sr, was calculated as the average of all 18 segments and indexed to early transmittal inflow velocity in order to calculate E/e'sr. Multivariable linear regression models were used to investigate associations between e'sr, E/e'sr, E/e' and kidney parameters. Models were adjusted for eGFR, UACR, LV ejection fraction (LVEF), age, sex, ever smoker, diabetes, hypertension, systolic and diastolic blood pressure (BP), heart rate and body mass index (BMI). We performed sensitivity analysis by excluding patients with known coronary artery disease (CAD) and heart failure (HF).

Results

Seventy-six patients had no measures of E/e'sr available leaving 749 for analysis. Excluding patients with CAD and/or HF (n=88) left 661 patients. For clinical and echocardiographic variables, see table. Patients with lower e'sr were older, had higher blood pressure and lower LVEF and GLS. E'sr was independently associated with eGFR and decreased 0.014 s–1 (95% CI 0.006 to 0.022, p=0.002) pr. 10 mL/min/1.73 m2 decrement of eGFR. Similarly, E/e'sr increased 1.1% (95% CI 0.2% to 19.2%) pr. 10 mL/min/1.73 m2 decrement of eGFR indicating rise in LV filling pressures. Contrary, E/e' was not independently associated with eGFR (p=0.5). Sensitivity analysis did not change the results significantly. None of the three measures were independently associated with UACR. Cubic restricted splines of e'sr, E/e'sr, E/e' over eGFR (figure) showed a non-linear relationship between E/e'sr and eGFR with accelerated increase at eGFR below 40 ml/min/1.73 m2.

Conclusion and perspectives

In patients with CKD, deformation-based e'sr and E/e'sr are independently associated with eGFR, but not with UACR. Repeated measurements and longitudinal follow-up of the cohort will provide information on the prognostic performance of these novel measures compared with conventional measures of LV filling pressure.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): The Capital Region of Denmark

3052Non-vitamin K antagonist oral anticoagulants are safe and effective alternatives to warfarin across subgroups by renal function: results from Danish registries

Background

All non-vitamin K antagonist oral anticoagulants (NOACs) have some degree of renal excretion, and patients with severely reduced renal function have been excluded from randomized controlled clinical trials of stroke prevention in atrial fibrillation (AF). Influence of renal function on outcomes has not been assessed in previous real-world studies of NOACs in AF.

Purpose

To assess influence of renal function on efficacy and safety of dabigatran, rivaroxaban or apixaban vs. warfarin.

Methods

Using nationwide registries, we identified all Danish AF patients who initiated warfarin, dabigatran, rivaroxaban or apixaban between 2012 and 2016. We included patients with a plasma creatinine measurement within 14 days from drug initiation and calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Hazard ratio (HR) of stroke/thromboembolism (TE) or major bleeding according to oral anticoagulation was calculated using multivariable-adjusted Cox regression analyses with warfarin as reference.

Results

We included 14,673 AF patients who started first-time oral anticoagulation within 14 days from AF diagnosis, and our study population comprised 2482 (16.9%) initiators of dabigatran (median age 72, 44.5% women), 3806 (25.9%) initiators of rivaroxaban (median age 75, 48.0% women), 5067 (34.5%) initiators of apixaban (median age 76, 48.8% women), and 3318 (22.6%) initiators of warfarin (median age 75, 45.4% women). eGFR was >50, 30–50 and 15 to <30 mL/min/1.73m2 in 10,281 (83.1%), 2079 (14.2%) and 404 (2.8%) patients at baseline. After adjustment for age, sex, year of inclusion, income, cohabitation status, eGFR, hemoglobin, medications and comorbidities, the HRs for stroke/TE compared to warfarin were 0.94 (95% confidence interval (CI) 0.74–1.20) for dabigatran, 1.06 (CI 0.84–1.34) for rivaroxaban, and 1.10 (CI 0.88–1.36) for apixaban. There were no significant heterogeneities in HRs of stroke/TE across subgroups by eGFR. Apixaban (HR 0.74, CI 0.62–0.89) was associated with lower risk of major bleeding compared to warfarin, rivaroxaban (HR 1.06, CI 0.88–1.27) with risk of major bleeding comparable to warfarin, and there were no significant heterogeneities in risk of major bleeding with rivaroxaban or apixaban across subgroups by eGFR. Dabigatran was associated with lower risk of bleeding among patients with eGFR >50 mL/min/1.73m2, but not among patients with eGFR 30–50 mL/min/1.73m2 (interaction P=0.03).

Conclusions

In a large real-world cohort, renal function had no significant influence on efficacy or safety of apixaban or rivaroxaban when compared with warfarin. Dabigatran was associated with lower risk of bleeding among patients with normal or mildly decreased renal function, but not among patients with moderately decreased renal function.

Acknowledgement/Funding

This study was funded by an unrestricted grant from the Capital Region of Denmark, Foundation for Health Research.

Circulating chromatin-anti-chromatin antibody complexes bind with high affinity to dermo-epidermal structures in murine and human lupus nephritis

Murine and human lupus nephritis are characterized by glomerular deposits of electron-dense structures (EDS). Dominant components of EDS are chromatin fragments and IgG antibodies. Whether glomerular EDS predispose for similar deposits in skin is unknown. We analysed (i) whether dermo-epidermal immune complex deposits have similar molecular composition as glomerular deposits, (ii) whether chromatin fragments bind dermo-epidermal structures, and (iii) whether deposits in nephritic glomeruli predispose for accumulation of similar deposits in skin. Paired skin and kidney biopsies from nephritic (NZBxNZW)F1 and MRL-lpr/lpr mice and from five patients with lupus nephritis were analysed by immunofluorescence, immune electron microscopy (IEM) and co-localization TUNEL IEM. Affinity of chromatin fragments for membrane structures was determined by surface plasmon resonance. Results demonstrated (i) presence of EDS containing chromatin fragments and IgG in both organs in nephritic patients, (ii) chromatin fragments possessed high affinity for dermo-epidermal laminins and collagens, (iii) glomerular immune complex deposits did not predict similar interstitial deposits in skin, although such complexes were present in capillary lumina in glomeruli and skin of all nephritic individuals. Thus, chromatin-IgG complexes accounting for lupus nephritis seem to reach skin through circulation, but other undetermined factors are required for these complexes to deposit within skin membranes.

High serum enalaprilat in chronic renal failure

BACKGROUND

Most angiotensin-converting enzyme (ACE) inhibitors and their metabolites are excreted renally and doses should hence be reduced in renal insufficiency. We studied whether the dosage of enalapril in daily clinical practice is associated with drug accumulation of enalaprilat in chronic renal failure.

METHODS

Fifty nine out-patients with plasma creatinine >150 micromol/L and chronic antihypertensive treatment with enalapril were investigated, in a cross-sectional design.

RESULTS

Median glomerular filtration rate (GFR) was 23(range 6-60) ml/minute/1.73 m2. The daily dose of enalapril was 10 (2.5-20) mg and the trough serum concentration of enalaprilat was 31.8 (<2.5-584.7)ng/ml. Ninety percent of the patients had higher serum concentrations of enalaprilat than has been reported in subjects with normal kidney function, and a marked elevation of serum enalaprilat was observed in patients with GFR <30 ml/minute. All but three patients had serum ACE activity below the reference range. The ACE genotype did not influence the results. Additional pharmacokinetic studies were done in nine patients in whom GFR was 23 (10-42)ml/minute/1.73 m2. The median clearance of enalaprilat was 28 (16-68) ml/minute and correlated linearly with GFR (r=0.86, p=0.003). Intra-subject day-to-day variation in trough concentrations was 19.7%.

CONCLUSION

Patients with chronic renal failure given small or moderately high doses of enalapril may thus have markedly elevated levels of serum enalaprilat. Whether this affords extra renoprotection, or on the contrary may inappropriately impair renal function, is not known, and should be investigated in prospective, controlled studies.

Uricosuric effect of losartan in patients with renal transplants

BACKGROUND

The aim of the study was to evaluate the uricosuric effect of the angiotensin II receptor antagonist, losartan, in hypertensive patients with renal transplants who are treated with cyclosporin A (CsA).

METHODS

Twenty-six patients with stable renal function and hypertension, 16 men and 10 women, median age 47 years (range, 25-63 years), were studied in an open randomized crossover trial, comparing a 2-week control period with a 2-week period of once-daily administration of 50 mg of losartan. The main outcome measurements were fractional excretion of uric acid (FE(uric acid)) based on 24-hr urine collections and plasma uric acid.

RESULTS

The median FE(uric acid) was 5.7% (range, 2.4-10.4%) in the control period with a median change of +0.84% (range, -1.15% to +2.77%) in the losartan period (P<0.0002). Plasma uric acid was 0.47 mM (0.29-0.69 mM) in the control period with a change of -0.03 mM (-0.10 to 0.06 mM) in the losartan period (P<0.002). Diastolic blood pressure was 87 mmHg (70-97 mmHg) in the control period with a change of -3 mmHg (-13 to +6 mmHg) in the losartan period (P<0.005). There was no difference in systolic blood pressure between the two study periods. Plasma creatinine was 165 microM (102-356 microM) in the control period with a change of +9 microM (-36 to +60 microM) in the losartan period (P<0.01). Plasma potassium was 4.2 mM (3.0-4.7 mM) in the control period with a change of + 0.2 mM (-0.2 to +0.9 mM) in the losartan period (P<0.0005).

CONCLUSIONS

Once-daily administration of 50 mg of losartan in hypertensive CsA-treated patients with renal transplants caused a 17% increase in FE(uric acid) and an 8% fall in plasma uric acid.

[Living-donor kidney transplantation]

In recent years transplantation from living donors has accounted for 25-30% of all kidney transplants in Denmark corresponding to 40-45 per year. Most of these living donors are parents or siblings, although internationally an increasing number are unrelated donors. Donor nephrectomy is associated with only few complications. The long-term outcome for kidney donors is good without increase in mortality or risk for development of hypertension and renal failure; proteinuria may be seen. Living kidney transplantation is the optimal treatment of end-stage renal disease with better graft survival than in cadaver transplantation. The ethical and psychological aspects related to transplantation from a living donor are complex and need to be carefully evaluated when this treatment is offered to the patients.

Urinary excretion of Tamm-Horsfall protein and epidermal growth factor in chronic nephropathy

Tamm-Horsfall protein (THP) and epidermal growth factor (EGF) are both synthesized by tubular cells in the distal part of the nephron and excreted with the urine. The present study examines the urinary excretion rates of the two peptides in relation to functional tubular markers in patients with chronic nephropathy. Four groups of patients with moderate to severely reduced renal function were studied: glomerulonephritis (n = 10), diabetic nephropathy (n = 11), tubulointerstitial nephropathy (n = 13), and polycystic kidney disease (n = 8). The renal function was evaluated by glomerular filtration rate (GFR) as an indicator for the general renal function, lithium clearance (C(Li)) as an indicator for proximal tubular function, and absolute distal reabsorption of sodium (ADR(Na)) as an indicator for distal tubular function. The excretion rate of EGF was rather closely correlated with GFR, C(Li) and ADR(Na) (Spearman coefficients of variation 0.88, 0.69, and 0.74, respectively). The correlations between the excretion rate of THP and GFR, C(Li) and ADR(Na) were weaker (Spearman coefficients of variation 0.68, 0.42, and 0.44). When the effect of GFR had been accounted for by multiple variance analyses, the excretion rates of the two peptides were still associated with ADR(Na) but not with C(Li). In conclusion, the urinary excretion rates of especially EGF but also those of THP were correlated with renal function and distal tubular reabsorption of sodium in patients with chronic nephropathy.

Tamm-Horsfall protein in urine after uninephrectomy/transplantation in kidney donors and their recipients

Tamm-Horsfall protein (THP) is a large glycoprotein with unknown physiological function synthesized in the thick ascending limb of the loop of Henle. Urinary THP has recently been suggested as being suitable for monitoring the functional state of transplanted kidneys. In the present study, the urinary excretion of THP after uninephrectomy and transplantation among relatives was determined in order to study the influence of the acute reduction in renal mass on the excretion of this peptide. Glomerular filtration rate (GFR), estimated by the plasma clearance of 51Cr-EDTA, and the excretion rate of THP were measured 2 days before nephrectomy and 5, 12, 26 and 54 days after nephrectomy/transplantation in 22 healthy living kidney donors and in 16 of their recipients. In the donors, THP excretion rate of the kidney to remain in the donor was 22.3 micrograms/min before and 33.7 micrograms/min at 5 days after uninephrectomy (p < 0.01) and remained increased by around 40% throughout the study period. GFR of the remaining kidney rose from 47 ml/min before to 61 ml/min at 5 days after uninephrectomy (p < 0.001). The THP excretion rate/GFR ratio remained unchanged in the donors. In the kidney to be transplanted, THP excretion rate was unchanged before and after transplantation. There was no significant increase in GFR in the recipients, which was significantly lower than GFR of the donors all the time. In matched pairs of kidney donors and recipients, the THP excretion rate/GFR ratio tended to be lower in the recipients but the difference was not significant. The correlation between excretion rate of THP and GFR was significant (r = 0.66; p < 0.01). To conclude, uninephrectomy in healthy man was associated with a marked increase of around 40% in the excretion of THP from the kidney that remained in the donor. In the kidney that was transplanted, the THP excretion rate was unchanged. The THP excretion rate was correlated with GFR. The mechanism underlying this association is unknown as THP does not undergo glomerular filtration.

The influence of angiotensin-converting enzyme inhibition on renal tubular function in progressive chronic nephropathy

The influence of angiotensin-converting enzyme (ACE) inhibition on renal tubular function in progressive chronic nephropathy was investigated in 69 patients by the lithium clearance (C(Li)) method. Studies were done repeatedly for up to 2 years during a controlled trial on the effect of enalapril on progression of renal failure. The pattern of proteinuria was followed over the first 9 months. At baseline, the glomerular filtration rate (GFR) was 5 to 68 mL/min. Absolute proximal tubular reabsorption rate of fluid (APR), estimated as the difference between GFR and C(Li), was 1 to 54 mL/min. Calculated fractional proximal reabsorption (FPR) was moderately subnormal. During the study, GFR decreased and sodium clearance was unchanged; fractional excretion of sodium therefore increased. In the group of patients randomized to treatment with enalapril (n = 34), GFR at 1 month was 83% (P < 0.001) and C(Li) was 88% (P < 0.01) of the baseline values, APR and FPR had not changed significantly, and potassium clearance was significantly decreased. Through the rest of the study period, APR remained nearly unchanged and FPR even increased in the enalapril group. In the group of patients randomized to treatment with conventional antihypertensive drugs (n = 35), C(Li) was unchanged until severe reduction in GFR, APR and FPR decreased gradually, and potassium clearance was almost unchanged. These differences in tubular function between the two treatment regimens were significant (P < 0.05). An unchanged or increased APR in either treatment regimen was associated with a long-term slower progression of renal failure. Over 9 months, the 24-hour fractional clearance of albumin decreased in the ACE inhibitor group (P < 0.01), whereas the clearances of immunoglobulin G and retinol-binding protein were unchanged in this group. In the conventional group, the fractional clearances of these three plasma proteins all increased. It is concluded that in progressive chronic nephropathy ACE-inhibitor treatment was associated with different adaptive tubular changes in the handling of sodium, water, and protein compared with conventional antihypertensive therapy. During ACE inhibition, the reabsorptive capacity of the proximal tubule appeared to be better preserved, which might be of importance for the beneficial effect of this treatment in chronic renal disease.

Urinary excretion of epidermal growth factor in living human kidney donors and their recipients

Epidermal growth factor (EGF) is a growth-promoting peptide that is synthesized in the distal tubules of the kidney and excreted in urine. EGF has been suggested to play a role in the repair after renal tissue damage, as well as in compensatory growth of the remaining kidney after uninephrectomy. The present study examined the urinary EGF excretion after uninephrectomy and transplantation among relatives. The urinary EGF excretion rate and the glomerular filtration rate (GFR) were followed for 26-54 days in 16 healthy kidney donors and nine recipients. After uninephrectomy the median urinary EGF excretion rate in the donors was not 50% of the pre-operative value, but around 65% (95% confidence limits of the median on the fifth post-operative day: 59-72%). This suggests that there is a compensatory increase in the EGF excretion rate from the remaining kidney of around 30% after uninephrectomy. A similar compensatory increase was demonstrated for GFR, indicating that the compensatory changes in EGF excretion rate and GFR might be correlated. In the transplanted kidneys, GFR was consistently around 15% lower and EGF excretion rate around 40% lower than in the corresponding kidneys remaining in the donors. This might reflect ischaemic and drug-induced damage of the transplanted kidneys. The present study demonstrated a compensatory increase of around 30% in urinary EGF excretion from the remaining kidney after uninephrectomy in healthy humans. Whether EGF plays a role in the adaptive processes in the remaining kidney or whether changes in EGF excretion are merely of a secondary nature is still uncertain.

Glomerular filtration rate and segmental tubular function in the early phase after transplantation/uninephrectomy in recipients and their living-related kidney donors

1. Glomerular filtration rate and sequential tubular function were investigated in 18 adult renal transplant recipients and in their matched, adult living-related kidney donors before and 5 days after transplantation/uninephrectomy. At day 54, 13 donors and 11 recipients were re-investigated. Sixteen of these constituted eight matched pairs. This reduction in the study population was caused by the application of two withdrawal criteria. 2. In the recipients glomerular filtration rate was unchanged at day 5 and had increased to 61 ml/min at day 54 (P < 0.05). In the donors glomerular filtration rate had increased to 59 ml/min by day 5 (P < 0.01) and was unchanged at day 54. 3. In the recipients lithium clearance was unchanged at day 5 and had increased to 23 ml/min at day 54 (P < 0.01). In the donors the lithium clearance had increased by day 5 (P < 0.01). 4. In the recipients the absolute proximal fluid reabsorption rate was about 36 ml/min throughout the study period. In the donors the absolute proximal fluid reabsorption rate had increased to 42 ml/min by day 5 (P < 0.05) and increased further to 44 ml/min by day 54 (P < 0.01). 5. In the recipients sodium clearance increased from 0.54 ml/min to 2.10 ml/min at day 54 (P < 0.01). In the donors it increased from 0.64 ml/min to 0.99 ml/min at day 54 (P < 0.05). 6. Donor-recipient comparison showed that at day 54 there was no significant difference with regard to glomerular filtration rate, lithium clearance, absolute and fractional proximal fluid reabsorption rate and absolute distal sodium reabsorption rate.(ABSTRACT TRUNCATED AT 250 WORDS)

[Angiotensin I converting enzyme inhibitor enalapril in treatment of progressive chronic nephropathy. An open randomized controlled trial]

In order to study the influence of angiotensin converting enzyme (ACE) inhibition on the progression of chronic nephropathy, 70 patients with a median glomerular filtration rate (GFR) of 15 (range, 6 to 54) mL/min/1.73 m2 were randomised in an open study to basic treatment with enalapril or conventional antihypertensive treatment. The patients were followed for at least two years or until they needed dialysis. The therapeutic goal, was a blood pressure of 120 ti 140/80 to 90 mmHg. In the enalapril group, the median decline in GFR was -0.20 (range, +0.18 to -7.11) mL/min/1.73 m2/month, and in the control group, it was -0.31 (+0.01 to -1.97) mL/min/1.73 m2/month (p < 0.05). There was no significant difference in blood pressure between the groups. Thus, the progression of moderate to severe chronic nephropathy was slower on a basic treatment with enalapril as compared to conventional antihypertensive therapy.

Effect of enalapril on the progression of chronic renal failure. A randomized controlled trial

In order to study the influence of angiotensin converting enzyme (ACE) inhibition on the progression of chronic nephropathy, 70 patients with a median glomerular filtration rate (GFR) of 15 (range, 6 to 54) mL/min/1.73 m2 were randomized in an open study to basic treatment with enalapril or conventional antihypertensive treatment. The patients were followed for at least 2 years or until they needed dialysis. The groups were comparable with respect to age and sex distribution, etiology of renal diseases, initial levels of renal function and arterial blood pressure (BP), and protein intake. The therapeutic goal was a BP of 120 to 140/80 to 90 mm Hg. The GFR, estimated by the plasma clearance of 51Cr-EDTA, was measured every third month, and the individual rate of progression was calculated as the slope of the GFR v time plot. In the enalapril group, the median decline in GFR was -0.20 (range, +0.18 to -7.11) mL/min/1.73 m2/month and in the control group it was -0.31 (+0.01 to -1.97) mL/min/1.73 m2/month (P less than .05). There was no significant difference in blood pressure or plasma lipid levels between the groups. Thus, the progression of moderate to severe chronic nephropathy was slower on a basic treatment with enalapril as compared to conventional antihypertensive therapy.

Angiotensin converting enzyme (ACE) inhibitors and renal function. A review of the current status

Angiotensin converting enzyme (ACE) inhibitors are well established in the treatment of hypertension and cardiac failure. Experimental studies in rats have suggested that these agents may protect renal function in chronic nephropathy by a mechanism other than simply lowering the systemic blood pressure. In human studies of incipient diabetic nephropathy, worsening of microalbuminuria was prevented during 3 years of ACE inhibition. ACE inhibitors reduce arterial blood pressure in chronic nephropathy, and may cause a fall in glomerular filtration rate. In diabetic nephropathy, proteinuria was reduced by 2 months' treatment with enalapril to less than half of the values obtained in a control group treated with metoprolol. Nonrandomised trials have suggested that ACE inhibitors may slow the deterioration of renal function, but no comparisons with other antihypertensive agents in prospective studies have been published to date. In chronic renal failure, ACE inhibitors may worsen anaemia and hyperkalaemia. Renovascular hypertension can be treated with ACE inhibitors, but the treatment may lead to a compromised renal function. The dosage of these drugs should be reduced in renal failure and therapy should be started cautiously in this setting, with close monitoring of blood pressure, renal function and plasma potassium.

Atrial natriuretic peptide and renal adaptation to contralateral nephrectomy in healthy man

Atrial natriuretic peptide (ANP), angiotensin II (AII), aldosterone (Aldo) and arginine vasopressin (AVP) in plasma were determined in 12 healthy renal transplant donors before and 5, 12, 26, 54 days after uninephrectomy (Nx) in order to study the possible role of these hormones in functional adaptation to acute reduction in renal mass. Glomerular and tubular function was studied by measurements of the clearances of 51Cr-EDTA, lithium, sodium, potassium, and albumin. ANP was 7.4 +/- 3.1 pmol l-1 (mean +/- SD) before Nx and 8.7 +/- 6.1 pmol l-1 at 5 days after Nx and remained at this level through the observation period. Aldo showed a non-significant transient fall at 5 days after Nx. AII and AVP remained normal after Nx. At 5 days after Nx glomerular filtration rate (GFR) of the remaining kidney had risen from 45 +/- 7 ml min-1 before Nx to 57 +/- 8 ml min-1 (p less than 0.01), lithium clearance had risen from 13 +/- 2 ml min-1 before Nx to 20 +/- 7 ml min-1 (p less than 0.01), and sodium and water balance was normal. To conclude, plasma ANP, AII, Aldo and AVP do not appear to be responsible for the hyperfiltration and depression of fractional proximal sodium and water reabsorption observed in recently uninephrectomized man with normal sodium and water balance.

Effect of enalapril on haemoglobin and serum erythropoietin in patients with chronic nephropathy

It has been suggested that angiotensin-converting enzyme (ACE) inhibitors halt the progression of chronic renal failure. During the first months of a controlled trial of this hypothesis a fall in haemoglobin (Hb) was observed in patients treated with the ACE inhibitor enalapril. It was investigated whether this was related to changes in serum erythropoietin (EPO). Data were analysed in 59 consecutive patients during an observation period of 90 days. In enalapril-treated patients (n = 27) Hb fell gradually from a median value of 7.6 to 6.7 mmol/l at 90 days of treatment. In the control group of patients on conventional antihypertensive treatment (n = 32) median Hb was unchanged (7.6 mmol/l) throughout the observation period (p less than 0.001 enalapril vs control). In the enalapril-treated group median EPO concentration fell from 32 to 24 U/l at 90 days of treatment, whereas in conventionally treated patients median EPO was 34 U/l and 35 U/l, respectively (p less than 0.05 enalapril vs control). Neither glomerular filtration rate nor arterial blood pressure differed significantly in the two groups. Furthermore, there were no signs of bone marrow suppression, increased haemolysis or change in plasma volume. In conclusion, a decrease in Hb was found after start of treatment with enalapril in patients with progressive chronic renal failure, possibly caused by a suppression of EPO production.

Renal uptake of dimercaptosuccinic acid and glomerular filtration rate in chronic nephropathy at angiotensin converting enzyme inhibition

Glomerular filtration rate (GFR) and renal uptake of dimercaptosuccinic acid (DMSA) were measured in 31 patients with progressive chronic nephropathy before and immediately after the start of treatment with angiotensin converting enzyme (ACE) inhibitor in order to control adverse effects on kidney function. Scintigrams of the kidneys showed an unaltered distribution of DMSA during treatment. GFR estimated by 51Cr-EDTA plasma clearance fell by 14% (P less than 0.01), but renal uptake of 99mTc-DMSA increased by 10% (P less than 0.01). It is concluded that DMSA in chronic renal failure is mainly taken up by the tubular cells from the peritubular capillaries since the uptake was unaffected by the acute decrease in GFR.

Initial effect of enalapril on kidney function in patients with moderate to severe chronic nephropathy

Angiotensin converting enzyme (ACE) inhibitors has been suggested to halt the progression of chronic renal failure. As the initial step of a controlled trial of this hypothesis, it was investigated whether start of enalapril in patients with severe chronic nephropathy might cause a critical fall in their renal function. Thirty-one patients were studied, 26 on chronic antihypertensive treatment with drugs other than ACE inhibitors and 5 untreated normotensive. 51Cr-EDTA plasma clearance and renal technetium-99m dimercaptosuccinic acid (99mTc-DMSA) scintigraphy were made before and 24 h after start of enalapril, mean dose 9 mg. Blood pressure fell from median 148/88 to 119/78 mmHg (p less than 0.01). Glomerular filtration rate (GFR) fell from median 14 to 12 ml/min/1.73 m2 (p less than 0.01). The median change in GFR was -14% (range -44% to +10%). The split renal function was unchanged and the scintigrams showed no intrarenal activity defects. In conclusion, enalapril caused a fall in GFR, which was clinically acceptable in most of the patients.

Scintigraphic demonstration of the thoracic duct following oral ingestion of 123I-heptadecanoic acid

A new noninvasive method for scintigraphic demonstration of the anatomic localization and function of the thoracic duct is described. Seven volunteers ingested 123I-heptadecanoic acid; approximately one hour later the entire thoracic duct was demonstrated and correspondingly a sharp rise in the plasma appearance rate of radioactivity was recorded. The method is simple and without side effects. The usefulness of this examination in clinical practice remains to be elucidated.

[Irreversible renal failure during treatment with angiotensin I converting enzyme inhibitor in bilateral renal stenosis]

A case of irreversible renal failure during treatment with enalapril in bilateral renal artery stenosis is described. In the use of converting enzyme inhibitors, caution and monitoring of renal function during treatment is advised.

51Cr-EDTA plasma clearance in severe renal failure determined by one plasma sample

Two hundred and thirty-four measurements of standard 51Cr-EDTA plasma clearance were made in 50 patients with severe chronic renal failure. Based on these data two calculation methods were attempted using one plasma sample drawn 24 h after injection of 51Cr-EDTA. One of the methods used the 'one sample clearance' formulas disregarding exact time of plasma sampling. This method might provide values 3.1 ml/min below or 2.9 ml/min above the established method of total 51Cr-EDTA plasma clearance, and would thus provide insufficient agreement. In the other method an estimate of plasma activity at zero-time was derived from injected dose and body surface area. This method might provide values 1.5 ml/min below or 0.8 ml/min above the established method of 51Cr-EDTA plasma clearance, which would be acceptable for clinical purposes. It is concluded that exact plasma clearance of 51Cr-EDTA in severe renal dysfunction (estimated clearance values below 21 ml/min) may be determined with adequate precision by one plasma sample drawn at 24 h after injection of the tracer without sampling at 5 h. This appears to be a very practical simplification.

Lithium clearance in chronic nephropathy

1. Lithium clearance measurements were made in 72 patients with chronic nephropathy of different aetiology and moderate to severely reduced renal function. 2. Lithium clearance was strictly correlated with glomerular filtration rate, and there was no suggestion of distal tubular reabsorption of lithium or influence of osmotic diuresis. 3. Fractional reabsorption of lithium was reduced in most patients with glomerular filtration rates below 25 ml/min. 4. Calculated fractional distal reabsorption of sodium was reduced in most patients with glomerular filtration rates below 50 ml/min. 5. Lithium clearance data were independent of whether renal disease was of primarily glomerular or tubular origin and, further, were not influenced by long-term conventional antihypertensive treatment. 6. It is concluded that, even with a reduced kidney function, the data are compatible with the suggestion that lithium clearance may be a measure of the delivery of sodium and water from the renal proximal tubule. With this assumption it was found that adjustment of the sodium excretion in chronic nephropathy initially takes place in the distal parts of the nephron (loop of Henle, distal tubule and collecting duct). With more severe impairment the proximal tubule also becomes involved in the adjustment.

The influence of body posture on lithium clearance

To establish appropriate standard circumstances for lithium clearance measurements, a study was undertaken in 12 healthy volunteers. In each subject, the glomerular filtration rate (GFR), as estimated by [51Cr]EDTA plasma clearance, and the renal clearances of lithium, sodium and potassium were measured four times at 1-week intervals: two in the supine and one in the sitting position, and one when the subject was walking around. Glomerular filtration rate was not influenced by posture changes. On the contrary, lithium clearance, which in the supine position was 30 +/- 9 ml/min (1 SD), tended to fall in the sitting position, and fell significantly to 26 +/- 5 ml/min (p less than 0.025) in walking subjects. Absolute proximal tubular reabsorption rate of fluid correspondingly rose from 83 +/- 16 to 92 +/- 15 ml/min (p less than 0.005) and sodium clearance fell from 1.52 +/- 0.81 to 1.00 +/- 0.52 ml/min (p less than 0.05) in walking subjects. Absolute distal reabsorption of sodium decreased during walking from 4052 +/- 1219 to 3449 +/- 658 mumol/min (p less than 0.025), while fractional distal reabsorption of sodium was unchanged. Our results show a rise in proximal tubular reabsorption during moderate physical activity. Hence, when renal tubular function is studied with the lithium clearance method, standardization of posture and physical activity is important. In such studies physical activity such as walking should particularly be avoided.

Effects of sulindac and naproxen in patients with chronic glomerular disease

Eight patients with chronic glomerulonephritis were treated with either naproxen or sulindac in an open randomized study to observe their effects on the urinary excretion of prostaglandins and renal function. Both drugs were given for 7 days. Naproxen caused a decrease (p less than 0.01) of 80% in prostaglandin PGE2 and decrease (p less than 0.01) of 55% in prostaglandin PGF2 alpha. Sulindac caused a decrease (p = 0.01) of 37% in PGE2 and a decrease (p less than 0.05) in PGF2 alpha of 13%. The decrease in urinary excretion of prostaglandins were greater (p less than 0.05) during the naproxen treatment. Naproxen caused a decrease (p less than 0.05) in 24-hour creatinine clearance of 14 ml/min, an increase (p less than 0.05) in plasma urea of 1.0 mmol/l, an increase (p less than 0.05) in plasma potassium of 0.4 mmol/l and a decrease (p less than 0.01) in 24-hour urinary excretion of albumin of 11 mumol. Sulindac did not change any of these parameters significantly. In conclusion, sulindac affects renal prostaglandin synthesis to a significantly minor degree than naproxen and contrary to naproxen it does not influence the renal function in patients with chronic glomerular disease.

Effect of emepronium bromide (Cetiprin) on symptoms and urinary bladder function after transurethral resection of the prostate. A double-blind randomized trial

75 patients were randomized to be treated with either emepronium bromide (Cetiprin) 200 mg 4 times a day or placebo after transurethral resection of the prostate. The patients were evaluated urodynamically pre- and postoperatively, and further evaluated by micturition symptom charts. No significant differences in symptoms or objective findings were found between the patients treated with emepronium bromide and those treated with placebo.

Reversible bladder denervation in acute polyradiculitis

A case of reversible bladder denervation in acute polyradiculitis is presented, in which both motor and sensory bladder involvement could be demonstrated using cystometry and denervation-hypersensitivity testing. Attention is drawn to the differential diagnosis to cauda equina syndromes of other etiologies, and treatment with prompt catheter drainage is emphasized. Catheter removal should be guided by disappearance of denervation supersensitivity, and residual urine control by non-invasive methods is recommended.