Steady state pharmacokinetics and dose equivalents of oral clodronate in renal failure.

OBJECTIVE: Clodronate is used in the treatment of osteoporosis, and malignancy-associated bone disease. The steady state pharmacokinetics and the dose equivalents of oral clodronate were assessed in subjects with various degrees of renal failure. MATERIALS AND METHODS: 1,600 mg of clodronate was given orally mornings for 11 days to 14 healthy volunteers (creatinine clearance, CLCr, > 80 ml/min), and 18, 12 and 16 subjects with mild (50 - 80 ml/min), moderate (30 - 50 ml/min) and severe (< 30 ml/min) renal failure, respectively. Trough drug levels at 4, 7 and 11 days, and concentration-time curves for 72 h after the last dose were followed. RESULTS: In all study groups, the trough drug levels achieved the kinetic steady state within 11 days. The area under the 24-h concentration-time curve (AUC0-24) enlarged and the elimination half-life (t1/2elim) prolonged progressively when the renal function was impaired. The maximum drug level and the time to maximum were not changed significantly in the renal failure. In the steady state phase, the diurnal drug excretion (E0-24) was not changed by the kidney function, but the renal drug clearance (CLD) decreased in close correlation with CLCr. The normal-to-failed AUC0-24 ratios in mild, moderate, and severe renal failure were 0.53, 0.43 and 0.31, respectively, when the ideally-matched counterpart was assumed as the normal reference to each renal failure group. CONCLUSIONS: In mild, moderate and severe renal failure, 53%, 43% and 31% oral clodronate doses, respectively, resulted in drug AUCs similar to those in controls with normal (> 80 ml/min) CLCR.

Hormonal deficiencies during and after Puumala hantavirus infection.

Previous reports have described panhypopituitarism associated with severe cases of hemorrhagic fever with renal syndrome (HFRS), but the prevalence of hormonal deficiencies after nephropathia epidemica (NE), a milder form of HFRS, has not been studied. This study was conducted in order to determine the prevalence of hormonal defects in patients with acute NE and during long-term follow-up. Fifty-four patients with serologically confirmed acute NE were examined by serum hormonal measurements during the acute NE, after 3 months, and after 1 to 10 (median 5) years. Thirty out of 54 (56%) patients had abnormalities of the gonadal and/or thyroid axis during the acute NE. After a median follow-up of 5 years, 9 (17%) patients were diagnosed with a chronic, overt hormonal deficit: hypopituitarism was found in five patients and primary hypothyroidism in five patients. In addition, chronic subclinical testicular failure was found in five men. High creatinine levels and inflammatory markers during NE were associated with the acute central hormone deficiencies, but not with the chronic deficiencies. Hormonal defects are common during acute NE and, surprisingly, many patients develop chronic hormonal deficiencies after NE. The occurrence of long-term hormonal defects cannot be predicted by the severity of acute NE.

Does uremia interfere with HbA1c results in the FPLC method with Mono S cation exchanger?

To study the effect of uremia on hemoglobin A1c determination by the Mono S FPLC method, samples from uremic patients, with and without diabetes, and controls, were analysed with a modified chromatography with enhanced resolution. Besides specific HbA1c, four minor peaks could be seen, included in routine HbA1c values. Two of these differed in concentration in the patient groups studied: a shoulder-like peak close to the specific HbA1c (S fraction) and a slightly less cationic minor peak (M fraction). Both S and M peaks were higher in uremic than in nonuremic subjects, but the M peak was associated more with diabetes. In the nondiabetic group, the mean routine HbA1c value was 0.8% units higher in uremic than nonuremic individuals. The specific HbA1c was nondependent on uremia. Thus, in uremic patients, there seems to be falsely elevated HbA1c values, mainly because of small interfering hemoglobin fractions, not specific HbA1c.

Skeletal deposition of clodronate is related to parathyroid function and bone turnover in dialysis patients.

AIMS: Bisphosphonates inhibit osteoclastic bone resorption, and in the future, they may also have a role in the therapy of renal osteodystrophy. Our aim was to study whether the severity of hyperparathyroidism has an effect on the clearance of clodronate via routes other than dialysis or kidneys (nonrenal, non-dialysis clearance, CL(NRD)), which most likely represents the deposition of the drug in the skeleton. METHODS: We studied 31 dialysis patients (9 female/22 male, aged 28 - 79, median 58 years), 18 on hemodialyis (HD) and 13 on peritoneal dialysis (PD). HD patients were studied on a non-dialysis day. An intravenous infusion of 300 mg clodronate was given during 60 min at 8:00 a.m. Blood, urine and PD fluid samples were collected for 1 + 24 h, and pharmacokinetic parameters were calculated. RESULTS: In PD patients, 7% of the infused drug was excreted into PD fluid within 24 h, and in those HD or PD patients with residual diuresis 11% was excreted via the kidneys. The highest CL(NRD) was seen in patients with the most severe hyperparathyroidism. There was a positive correlation between CL(NRD) and plasma intact PTH (r = 0.79, p < 0.001). CL(NRD) was also related to the serum levels of bone markers PINP (procollagen type I N-terminal propeptide, r = 0.81, p < 0.001), osteocalcin (r = 0.65, p < 0.001) and ICTP (type I collagen cross-linked telopeptide, r = 0.68, p < 0.001). However, even in the patients with normal PTH, more than one-third of the infused drug was taken up by bone. CONCLUSION: In dialysis patients, the skeletal deposition of clodronate is related to bone turnover being highest in severe hyperparathyroidism. However, even in the case of low turnover, the uptake of the drug in bone takes place in amounts that might be clinically significant.

Pharmacokinetics of clodronate in peritoneal dialysis patients.

OBJECTIVE: To study the pharmacokinetics of clodronate in patients on continuous ambulatory peritoneal dialysis (CAPD). DESIGN: A single intravenous dose pharmacokinetic study. SETTING: University hospital. PATIENTS: Ten CAPD patients (3 female, 7 male, age 39-79 year, median 55). METHODS: Clodronate disodium in serum, urine, and dialysate was collected for 24 hours and analyzed by capillary gas chromatography with mass-selective detection. RESULTS: Only 7% of the infused dose of clodronate was eliminated through peritoneal dialysis during 24 hours. Clearance via CAPD (CL[CAPD]) was 2.4 +/- 0.6 mL/min, which was less than 10% of the total serum clearance (CL(tot), 26.0 +/- 19.3 mL/min). Even the kidneys were a more important route of elimination than CAPD in those patients with residual diuresis of more than 500 mL/24 hr. However, in all patients most of the clodronate serum clearance (77% +/- 13%) took place via routes other than peritoneal dialysis or kidneys, that is, via nonrenal-non-CAPD clearance (CL[NRD]). CL(NRD) most likely represents the part of the drug deposited in the skeleton. There was a positive correlation between CL(NRD) and the plasma intact parathyroid hormone concentration. CONCLUSIONS: CAPD removed clodronate poorly from the circulation. Most clearance took place via routes other than CAPD or kidneys. This CL(NRD) most likely represents the skeletal deposition of the drug, and this is related to the severity of hyperparathyroidism. When treating CAPD patients with hyperparathyroid bone disease, the administration of clodronate should be adjusted as in those subjects with severe renal failure.

Ten-year prognosis of Puumala hantavirus-induced acute interstitial nephritis.

Nephropathia epidemica (NE) is a hemorrhagic fever with renal syndrome caused by Puumala hantavirus. Its long-term prognosis is considered favorable. There are, however, some reports about subsequent hypertension, glomerular hyperfiltration, and proteinuria after previous hantavirus infection. Therefore, we studied 36 patients 5 and 10 years after acute NE, with 29 seronegative controls. Office blood pressure, ambulatory 24-h blood pressure (ABP), glomerular filtration rate (GFR), and proteinuria were examined. Hypertensive subjects were defined as those patients having increased ambulatory or office blood pressure, or receiving antihypertensive therapy. Office blood pressure was used to define hypertension only if ABP was not determined. At 5 years, the prevalence of hypertension was higher among NE patients than in controls (50 vs 21%, P=0.020). At 10 years, the difference between the groups was no more significant (39 vs 17%, P=0.098). Five years after NE, patients showed higher GFR (121+/-19 vs 109+/-16 ml/min/1.73 m(2), P=0.012) and urinary protein excretion (0.19 g/day, range 0.12-0.38 vs 0.14 g/day, range 0.09-0.24, P=<0.001) than controls. At 10 years, there were no more differences in GFR or protein excretion between the groups (GFR: 113+/-20 vs 108+/-17 ml/min/1.73 m(2), P=0.370; proteinuria: 0.14 g/day, range 0.07-0.24 vs 0.13 g/day, range 0.06-0.31, P=0.610). In conclusion, the 10-year prognosis of NE is favorable, as glomerular hyperfiltration and slight proteinuria detected at 5 years disappeared during the longer follow-up. However, the possibility exists that NE may predispose some patients to the development of hypertension.

Effects of exercise on glomerular passage of macromolecules in patients with diabetic nephropathy and in healthy subjects.

The effects of exercise on glomerular permeability were investigated in 12 proteinuric insulin-dependent diabetic patients and in 12 healthy controls by measuring the fractional protein and dextran clearances at rest and after exercise. Exercise significantly reduced the glomerular filtration rate (GFR) and the renal plasma flow (RPF) and markedly increased the filtration fraction (FF) in both diabetics and controls. The fractional clearances of albumin and IgG increased significantly during exercise in diabetics. Exercise also significantly increased the fractional clearance of albumin in healthy controls. The changes in the fractional protein clearances correlated significantly with the changes in the FF. In diabetics the fractional dextran clearances of molecules with a radius greater than or equal to 4.8 nm were significantly elevated after exercise. This was not found in healthy controls. It is concluded that exercise increases glomerular permeability by influencing the renal haemodynamics. Probably partial depletion of negative charges on the glomerular capillary wall plays a role in exercise-induced proteinuria in both healthy and diabetic subjects. In addition, the altered glomerular permeability during exercise is associated with increased size of the filtering pores in diabetic nephropathy.

Fractional dextran and protein clearances in glomerulonephritis and in diabetic nephropathy.

The renal clearance of dextran and protein of different molecular sizes has been measured in 42 proteinuric patients with diabetes and glomerulonephritis. In both patient groups the fractional low molecular (radii 3.0-3.6 nm) dextran clearances were significantly decreased whereas the fractional high molecular (radii 5.1-7.8 nm) dextran clearances were increased as compared with the controls. A porosity/charge index was constructed by calculating the ratio of fractional clearances of neutral to anionic macromolecules (theta D3.6/theta ALB, theta D5.1/theta IgG). In diabetic patients the relation between the fractional clearances of neutral and anionic macromolecules was dependent on glomerular filtration rate. It seems likely that the altered glomerular permeability in diabetic nephropathy is associated with a decrease of charge as renal function deteriorates. In glomerulonephritis the process is different and there is a high degree of variation from case to case.

Proteinuria and renal function during and after acute urinary retention.

PURPOSE: Benign prostatic hyperplasia is the most common neoplasm as well as the main cause of bladder outlet obstruction in men. It may progress to involve a risk of urinary retention. We investigated the effects of acute urinary retention on renal function. MATERIALS AND METHODS: We evaluated renal function using biochemical markers in 25 men with a mean age of 69 years in whom an episode of acute urinary retention a mean of 31 hours in duration was due to bladder outlet obstruction. Patients were followed for 6 months after acute retention was relieved. Patients were not known to have had any renal disease previously. RESULTS: During acute urinary retention at presentation, and after 1 and 6 months we noted albuminuria in 100, 92 and 54% of patients, elevated alpha 1-microglobulin excretion in 54, 39 and 58%, and elevated beta 2-microglobulin excretion in 17, 19 and 9%. Serum creatinine or creatinine clearance did not predict proteinuria. All parameters became normal at 6 months in only 2 cases. CONCLUSIONS: Acute urinary retention affects glomerular and tubular renal function. After acute urinary retention was relieved increased glomerular permeability and tubular damage persisted in the majority of patients. This condition may have been partially due to previous long-term bladder outlet obstruction. Our findings stress the importance of the rapid recognition and treatment of acute urinary retention.

Cellular immunity in renal diseases.

Cellular immune reactivity was studied in 78 patients with various forms of renal disease by skin testing with four recall antigens and a lymphocyte transformation test with tuberculin PPD and leucoagglutinin. Patients with S-creatine greater than or equal to 230 micromol/l as well as those with chronic pyelonephritis who had S-creatinine values below 230 micromol/l had significantly lower skin reactions than the controls to streptokinase-streptodornase, parotitis and PPD. Glomerulonephritic patients with S-creatinine values below 230 micromol/l had normal skin reactivity. Lymphocyte transformation tests showed decreased reactivity only in patients with S-creatinine level greater than or equal to 230 micromol/l. The results suggest an association of chronic pyelonephritis with a defective efferent, nonspecific arm of cellular immunity.

Long-term renal dysfunction in patients with acute urinary retention.

OBJECTIVE: Acute urinary retention (AUR) causes bilateral renal obstruction, which has been found to affect kidney function. This study evaluated both glomerular and tubular renal function in the long term after the resolution of AUR. MATERIAL AND METHODS: Renal function in 15 patients affected by AUR and found still to evince renal dysfunction 6 months afterwards was re-evaluated approximately 18 months after the episode. The bladder outlet obstruction was treated and all patients voided normally at 6 month control. RESULTS: The percentage of patients suffering from lowered creatinine clearance and elevated alpha1-microglobulin excretion increased during follow-up from AUR up to 6 and 18 months (46% to 57% to 79% and 42% to 71% to 100%, respectively). In addition, daily protein excretion was abnormally high in 69% of patients at the 18 month follow-up. In most cases the abnormalities found in renal function were mild. CONCLUSION: Patients evincing renal dysfunction 6 months after AUR showed permanent impairment in tubular function, whereas glomerular permeability had partially recovered. Although this may be explained in part by chronic obstruction prior to AUR and although the impairment was mild in most cases, these findings stress the importance of urgent treatment of AUR to avoid the development of renal failure.

Characteristics of protein excretion in patients with acute urinary retention.

OBJECTIVE: To evaluate changes in protein leakage in the glomerular filtration barrier, and in the ability of the tubule to reabsorb proteins during and after acute urinary retention (AUR). PATIENTS AND METHODS: Glomerular and tubular function was investigated in 24 men during AUR (mean age 68 years, mean retention time 31 h and mean retention volume 1140 mL) who were then followed for 6 months by measuring the urinary excretion of glomerular and tubular proteins, and the glomerular filtration rate (GFR). Retention was relieved by inserting a suprapubic catheter and the cause of retention treated one month later. No patient had a previous renal disease or diabetes. RESULTS: During AUR, and after 1 and 6 months, albuminuria was detected in 100%, 92% and 54% of patients, and increased excretion of alpha1-microglobulin in 52%, 36% and 58%, of IgG in 79%, 58% and 40%, and of IgG4 in 67%, 42% and 20%, respectively. The mean GFR was normal during retention and during the follow-up. CONCLUSION: AUR causes disturbances in both the glomerular filtration and tubular reabsorption of proteins. Albuminuria and increased excretion of IgG, IgG4 and alpha1-microglobulin occurred in most patients during AUR. After relieving retention, the albuminuria and elevated alpha1-microglobulin excretion persisted, indicating slight glomerular dysfunction and a permanent defect in the proximal tubule to reabsorb proteins. This could be caused partly by previous chronic obstruction. AUR should be relieved immediately and the basic cause treated effectively to prevent further deterioration of renal function.

Intravenously administered frusemide increases glomerular permeability.

1. The effects of frusemide on glomerular permeability were investigated in eight proteinuric patients by measuring the fractional protein and dextran clearances and correlating these observations with changes in renal haemodynamics. 2. Frusemide increased significantly the fractional albumin and IgG clearances. The fractional dextran clearances of molecules with a radius greater than or equal to 5.4 nm also increased significantly after frusemide injection. Pretreatment with indomethacin partly inhibited the increments in clearances of macromolecules. 3. The changes in the fractional protein clearances correlated significantly with those of inulin clearance There was also a high degree of correlation between the changes in fractional protein clearances and prostanoid excretion. 4. The data obtained suggest that frusemide increases glomerular permeability by influencing the effective pores of the glomerular capillary wall. The increased permeability possibly is due to changes in prostanoid synthesis.

Interrelations of blood pressure, glomerular filtration rate, protein clearances and sodium excretion in patients with glomerulonephritis and diabetic nephropathy.

The roles of blood pressure and glomerular filtration rate in the renal handling of albumin, beta 2-microglobulin and sodium were studied by partial correlation analysis in 22 patients with glomerulonephritis and in 25 patients with diabetic nephropathy. The analysis showed that in these proteinuric patients blood pressure may have an independent role in the regulation of albumin excretion in both diseases. Fractional beta 2-microglobulin clearance and fractional excretion of sodium correlated significantly in both diseases. In the diabetic patients this correlation remained strong after removing the effect of blood pressure, whereas in the patients with glomerulonephritis control of blood pressure clearly decreased the correlation. This reflects differences in the renal handling of sodium and beta 2-microglobulin in patients with diabetic nephropathy and glomerulonephritis.

Reference intervals for the markers of proteinuria with a standardised bed-rest collection of urine.

Reference intervals for markers of proteinuria or glomerular charge selectivity were measured in 61 healthy female and 61 healthy male individuals. Timed bed-rest and daytime collections were used to assess significance of preanalytical variability of results. Bed-rest collections are advisable for research on renal damage, whereas in routine care, robust protein/creatinine ratios work as practical estimates of protein excretion rates, the correlations to excretion rates improving with increasing proteinuria. For glomerular charge selectivity, pancreatic/salivary isoamylase clearance ratio showed lower within-subject biological variation than IgG/IgG4 clearance ratio, allowing more accurate classification into normal and reduced charge selectivity. With our method, the lower 2.5% reference intervals for isoamylase clearance ratio were 1.1 in men and 1.9 in women.

Kidney ultrasound and Doppler ultrasound findings during and after acute urinary retention.

OBJECTIVE: To evaluate changes in kidney ultrasound and Doppler ultrasound images during and subsequent to acute urinary retention (AUR). METHODS: Twenty-five men with a mean age of 69 years suffering AUR for a mean of 31 h were studied by measuring serum creatinine, creatinine clearance and renal ultrasound. Renal Doppler ultrasound was applied in 19 of these cases and all patients were followed for 6 months after acute retention was relieved. RESULTS: During AUR hydronephrosis was noted in three patients; this disappeared during follow-up. During the acute period, after 1 month and after 6 months the average resistive indexes (RI) were 0.71, 0.70 and 0.69, respectively. The changes were not statistically significant. During follow-up, the proportion of patients with normal RI increased from 42 to 64%. Median serum creatinine was normal during retention and follow-up. Median creatinine clearance was reduced during retention and became normal during follow-up (P < 0.05). No correlation was found between RI and serum creatinine at any time-point, nor was any correlation noted between RI and creatinine clearance during retention or at the 1-month follow-up; at 6 months, however, there was a significant inverse correlation between them (P = 0.01). CONCLUSION: AUR caused elevation of RI, which may be interpreted as diminished renal blood flow. Although in the majority of patients it recovered after treatment, elevated RI was still found in one third of the patients, possibly due to previous chronic bladder outlet obstruction. Our findings stress the importance of both fast release of AUR and effective treatment of its cause.