Excretion of urinary enzymes after extracorporeal shock wave lithotripsy: a critical reevaluation

Evaluation of the process of recycling and renal parenchymal injury after eswl with metabolites excreted in the urine

OBJECTIVES

To show renal parenchymal injury depending on extracorporeal shock wave lithotripsy (ESWL).

METHODS

The patients with one renal stone and in whom ESWL is planned among the patients in whom renal stone was determined. Their 24-h urine samples were collected just before and after the ESWL treatment. Cit (citrate), UrA (uric acid), RBP (retinol-binding protein), NAG (N-acetyl-β-Đ-glucosaminidase), Cr (creatinine), Na (sodium), K (potassium), P (phosphor), Ca (calcium), and Cl (chlorine) metabolites excreted in urine were evaluated after urine samples were taken on the study day. Changes in the metabolites excreted; the number, frequency, and duration of ESWL shock wave; the energy; and the body mass index were recorded. The results for p < 0.05 will be accepted as statistically significant.

RESULTS

Two sessions of ESWL were applied to a total of 20 patients. When metabolites excreted in the urine before (B1E) and after (A1E) the first session of ESWL, and before (B2E) and after (A2E) the second session of ESWL, were evaluated, no statistically significant result for Ca and Cl excretion was noted. For NAG and Cr, a significant difference was observed in terms of metabolite excretion between B1E and B2E. For other metabolites, we saw that there is no difference between B1E and B2E. While a significant metabolite change was observed for RBP, NAG, Cr, and Na as long as A1E and A2E ESWL session number increases, other metabolites were not significant.

CONCLUSION

Shock waves induce significant damage to the renal and adjacent tissues as indicated by a significant increase in cell-escaped enzymes and electrolytes and the extent of damage depends on the energy and the number of shock wave exposure.

A prospective, randomized study of the clinical effects of shock wave delivery for unilateral kidney stones: 60 versus 120 shocks per minute

PURPOSE

We assessed the effects of different shock wave delivery rates in patients treated with shock wave lithotripsy for renal stones, particularly treatment success, degree of renal injury and pain experienced, and analgesic demand.

MATERIALS AND METHODS

A total of 206 patients with renal stones were prospectively randomized to receive shock waves delivered at 60 (group 1) or 120 (group 2) shocks per minute using a Sonolith® Vision at a single institution in October 2008 and August 2010. The primary outcome was successful treatment 12 weeks after 1 lithotripsy session. Secondary outcome measures included the degree of renal injury, as reflected by changes in urinary markers of renal injury, as well as patient pain scores and analgesia consumed during treatment.

RESULTS

Mean stone size in groups 1 and 2 was 8.95 and 9.28 mm, respectively (p = 0.525). The overall treatment success rate was 43.2%. It was significantly better in group 1 than in group 2 (50.5% vs 35.9%, p = 0.035). There was no between group difference in the success rate for stones 10 mm or less but the success rate was statistically better for group 1 patients with stones greater than 10 mm (p = 0.002). Immediately after shock wave lithotripsy there was a statistically significant greater increase in urinary NAG (p = 0.003) and interleukin-18 (p = 0.022) in group 1. There was no between group difference in pain scores, analgesic consumption during shock wave lithotripsy or unplanned hospital visits.

CONCLUSIONS

Slower shock wave delivery yielded better treatment outcomes, particularly for stones greater than 10 mm, without increasing patient pain or analgesic demand. However, slower shock wave delivery also appeared to cause a statistically significant increase in acute renal injury markers, although the clinical implication was uncertain.

Role of urinary biomarkers in the diagnosis of congenital upper urinary tract obstruction

Background:

Congenital obstructive uropathy constitutes a significant cause of morbidity in children. Currently, there is no reference standard for the diagnosis of renal obstruction in children. The noninvasive measurement of biomarkers in voided urine has considerable appeal as a potential application in children with congenital obstructive nephropathy. The aim of the present review is to explore the current role of biomarkers in the diagnosis and follow-up of obstructive uropathy in children.

Materials and Methods:

The literature database (PubMed) was searched from inception to May 2007 regarding the role of urinary biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Results:

The review included 23 experimental and 33 prospective controlled clinical studies. Several cytokines, peptides, enzymes and microproteins were identified as major contributors to or ensuing from obstruction-induced renal fibrosis and apoptosis. The most important biomarkers were transforming growth factor-β₁ (TGFβ₁), epidermal growth factor (EGF), endothelin-1 (ET-1), urinary tubular enzymes [N-acetyl-β-D-glucosaminidase (NAG), γ-glutamyl transferase (GGT) and alkaline phosphatase (ALP)], and microproteins [β₂-microglobulin (β₂M), microalbumin (M. Alb) and micrototal protein (M.TP)]. All biomarkers showed different degrees of success but the most promising markers were TGFβ₁, ET-1 and a panel of tubular enzymes. These biomarkers showed sensitivity of 74.3% to 100%, specificity of 80% to 90% and overall accuracy of 81.5% to 94% in the diagnosis of congenital obstructive uropathy in children. Moreover, some of the markers were valuable in differentiation between dilated non-obstructed kidneys in need of conservative management and obstructed kidneys in need of surgical correction. Some studies demonstrated that urinary biomarkers are helpful in the evaluation of success of treatment of children with congenital renal obstruction. Some limitations of the previous studies include lack of different types of controls and small sample size. Larger studies with variable controls are invited to confirm the clinical usefulness of biomarkers in the diagnosis and follow-up of children with congenital obstructive uropathy.

Conclusion:

Urinary biomarkers are a promising tool that could be used as a noninvasive assessment of congenital renal obstruction in children.

Effects of repeated extracorporeal shock wave in urinary biochemical markers of rats

PURPOSE

To access the effect of repeated extracorporeal shock wave (ESW) on urinary biochemical markers

METHODS

20 rats were assigned for ESW (Direx Tripter X1(R) - 14 KV) to one of two groups: G1 (n=10) one ESW; G2 (n=10) two ESWs within a 14-day interval. Within the twenty-four hour period before and after the application of shock waves, the animals were placed in metabolic cages for 24 hour urine collection. The ph, creatinine, sodium, potassium, chlorides, calcium, magnesium, phosphorus, oxalates, alkaline phosphatase and citrates were measured. Twenty-four hours after the material was collected for urinary determination, the animals underwent nephrectomy of the kidney submitted to the ESW applications and were, then, sacrificed. The kidneys were processed for histopathological examination.

RESULTS

Small variations in the biochemical markers were found in both groups, with no significant differences between the values obtained either prior to or following the ESW applications, except for citrate and alkaline phosphatase. Citraturia decreased significantly in group 2, following the second ESWL application (24.8 +/- 3.0 mg/day after the first ESWL vs. 15.3 +/- 2.2 mg/day after the second ESWL; p < 0.05). Alkaline phosphatase increased significantly following ESWL in group I (0.57 +/- 0.02 vs. 0.79 +/- 0.04 micromol/mg creatinine; p < 0.01) and also in group 2 (0.69 +/- 0.05 vs. 0.83 +/- 0.03 micromol/mg creatinine; p < 0.05). Glomerular, interstitial and sub-capsular hemorrhage with perivascular edema was found in the animals in both groups studied.

CONCLUSIONS

A significant increase in urinary alkaline phosphatase was found in both groups studied, suggesting a proximal tubule lesion. In the group of rats undergoing more than one ESWL application, a smaller urinary citrate excretion was noticed, which may be a factor contributing for the formation of new calculi.

Uranium in drinking water: renal effects of long-term ingestion by an aboriginal community

The authors conducted a study of an aboriginal community to determine if kidney func-tion had been affected by the chronic ingestion of uranium in drinking water from the community's drilled wells. Uranium concentrations in drinking water varied from < 1 to 845 ppb. This nonin-vasive study relied on the measurement of a combination of urinary indicators of kidney function and markers for cell toxicity. In all, 54 individuals (12-73 years old) participated in the study. Correlation of uranium excreted in urine with bio-indicators at p <or=.05 indicated interference with the kidney's reabsorptive function. Because of the community's concerns regarding cancer incidence, the authors also calculated cumulative radiation doses using uranium intake in drinking water over the preceding 15-year period. The highest total uranium intake over this period was 1,761 mg. The risk of cancer from the highest dose, 2.1 mSv, is 13 in 100,000, which would be difficult to detect in the community studied (population size = 1,480). This study indicates that at the observed levels of uranium intake, chemical toxicity would be a greater health concern than would radiation dose.

Diagnosis, epidemiology and outcomes of acute kidney injury

Acute kidney injury is an increasingly common and potentially catastrophic complication in hospitalized patients. Early observational studies from the 1980s and 1990s established the general epidemiologic features of acute kidney injury: the incidence, prognostic significance, and predisposing medical and surgical conditions. Recent multicenter observational cohorts and administrative databases have enhanced our understanding of the overall disease burden of acute kidney injury and trends in its epidemiology. An increasing number of clinical studies focusing on specific types of acute kidney injury (e.g., in the setting of intravenous contrast, sepsis, and major surgery) have provided further details into this heterogeneous syndrome. Despite our sophisticated understanding of the epidemiology and pathobiology of acute kidney injury, current prevention strategies are inadequate and current treatment options outside of renal replacement therapy are nonexistent. This failure to innovate may be due in part to a diagnostic approach that has stagnated for decades and continues to rely on markers of glomerular filtration (blood urea nitrogen and creatinine) that are neither sensitive nor specific. There has been increasing interest in the identification and validation of novel biomarkers of acute kidney injury that may permit earlier and more accurate diagnosis. This review summarizes the major epidemiologic studies of acute kidney injury and efforts to modernize the approach to its diagnosis.

Obstructed Versus Dilated Nonobstructed Kidneys in Children With Congenital Ureteropelvic Junction Narrowing: Role of Urinary Tubular Enzymes

PURPOSE

We evaluated the role of voided urine lysosomal enzyme N-acetyl-beta-D-glucosaminidase and brush border enzymes alkaline phosphatase and gamma-glutamyl transferase in differentiating between children with ureteropelvic junction obstruction in need of pyeloplasty and those with dilated nonobstructed kidneys suitable for conservative treatment.

MATERIALS AND METHODS

The study included 35 children with unilateral ureteropelvic junction obstruction treated with pyeloplasty (study group) and 15 children with dilated nonobstructed kidneys who were treated conservatively and followed for 15 months (control group). Voided urine samples were obtained before treatment from both groups, and from the study group at 1, 2, 3, 6, 9 and 12 months postoperatively and the control group at 3, 9 and 15 months of followup. N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase were measured in urine samples collected from both groups.

RESULTS

In the study group the activities of preoperative urinary N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase were significantly higher than in the control group. A cutoff value of 7.8 mU/mg creatinine N-acetyl-beta-D-glucosaminidase yielded a sensitivity of 97.1%, a specificity of 80% and an overall accuracy of 92%. A cutoff value of 34.5 IU/gm creatinine alkaline phosphatase resulted in a sensitivity of 91.4%, a specificity of 100% and an overall accuracy of 94%. A cutoff value of 54 IU/gm creatinine gamma-glutamyl transferase yielded a sensitivity of 62.9%, a specificity of 100% and an overall accuracy of 74%. The combination of urinary N-acetyl-beta-D-glucosaminidase and alkaline phosphatase resulted in a sensitivity of 100%, a specificity of 80% and an overall accuracy of 94%. Compared to preoperative activities, N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase decreased significantly at 12 months after pyeloplasty in the study group.

CONCLUSIONS

Voided urinary N-acetyl-beta-D-glucosaminidase, alkaline phosphatase and gamma-glutamyl transferase are accurate markers for differentiating between children with ureteropelvic junction obstruction requiring pyeloplasty and those with dilated nonobstructed kidneys suitable for conservative treatment. Measurement of these enzymes in voided urine could be used as a noninvasive tool for long-term followup of children with ureteropelvic junction obstruction after pyeloplasty and those receiving conservative treatment.

Urinary N-acetyl-beta-D-glucosaminidase concentration in patients with spinal cord injury: relationship with urodynamic parameters

OBJECTIVES

To investigate the relationships between urinary N-acetyl-beta-D-glucosaminidase (NAG) concentrations and urodynamic parameters in patients with spinal cord injury (SCI). NAG has been proposed as a marker of renal damage.

METHODS

Twenty-three patients with SCI were evaluated with urodynamic studies. Urine samples were collected from the 23 patients and 10 healthy volunteers, the NAG levels were evaluated, and the urodynamic parameters were compared with the urinary NAG levels. The patients were divided into two groups according to the amplitude of the hyperreflexic detrusor contractions (HDCs): group A, patients with an HDC amplitude of 40 cm H(2)O or greater, and group B, patients with an HDC amplitude of less than 40 cm H(2)O; group C was composed of healthy volunteers. The urinary NAG concentrations in the three groups were compared.

RESULTS

A positive correlation was found between the urinary NAG levels and the HDC amplitude and detrusor leak point pressure (P = 0.015 and 0.007, respectively). The urinary NAG concentration was 3.38 U/g in group A, 2.14 U/g in group B, and 2.12 U/g in group C. The differences in the urinary NAG concentrations between groups A and B and between groups A and C were statistically significant (P = 0.03 and P <0.001, respectively). The concentrations between groups B and C were comparable.

CONCLUSIONS

In our experience, the only urodynamic parameters that clearly and positively correlated with the urinary NAG levels were those expressing the amplitude of intravesical pressure. This result stresses the importance of reducing the intravesical pressure in patients with SCI using alternative treatments or surgical procedures if the usual conservative therapies are not effective.

Calculation of urinary enzyme excretion, with renal structure and function in dogs with pyometra

The urinary enzyme markers of renal damage, alkaline phosphatase (AP), gamma-glutamyl transferase (GGT) and N-acetyl-beta-glucosaminidase (NAG), glomerular filtration rate (GFR) and renal biopsies were studied to evaluate renal status in dogs with pyometra. After ovariohysterectomy, urinary enzymes were measured daily for 12 days in 55 dogs, and again at a later follow-up visit. Thirteen dogs had high levels of at least one enzyme at initial presentation. Seventeen dogs had a transient increase in urinary enzyme values between one and five days after surgery. Enzyme values usually declined to low activities within 12 post-operative days. Renal biopsies demonstrated tubular abnormalities in many dogs. Mean GFR was 2.4 and 2.0 ml min(-1) kg(-1), respectively on day 1 post-operatively and at the follow-up visit 1-4 months later. High urinary enzyme values often reflected extensive lesions in renal proximal tubular cells and sometimes reduced GFR.

Morphological correlates of urinary enzyme loss after extracorporeal lithotripsy

Urinary loss of the tubular marker enzyme N-acetyl-beta-D-glucosaminidase (NAG) immediately following extracorporeal lithotripsy suggests corresponding morphological changes in the kidney. To date, the morphological correlate of the enzymuria remains unclear. In this animal study with Wistar rats acute morphological changes in the tubulus cells beneath isolated tubulus necrosis were demonstrated. The mechanically induced lesions of the cell organelles included fragmentation of the lysosomes and severe alterations of the cell membrane. The tubulus damage was quantified. With the help of histochemical NAG staining and electron microscopic observations, a significant correlation between number and intensity of shock waves and tubular damage was found. The intracellular lesions described here are at least part of the morphological basis of shock-wave-induced enzymuria. The results show that enzymatic changes in urine reflect visible renal damage.

Treatment update on pediatric urolithiasis

At the doorstep of the twenty-first century the role of extracorporeal shock-wave lithotripsy (ESWL) as the treatment of choice for more than 80% of all stones in children is established. ESWL is safe and effective, with very few differences in success rates being observed among different lithotriptors. The present problem with ESWL appears to be the residual stone fragment, which has a proven clinical significance. A thorough metabolic evaluation and metaphylaxis is indicated in all children, and this will enable physicians to deal with the residual fragments in a more cause-specific manner and prevent regrowth. Another subject that needs prospective randomized studies to be unveiled is the assumption that a specific or universal metaphylaxis, possibly with alkaline citrates, will enhance stone clearance, lower the incidence of residual stone fragments, and optimize the ESWL results. Finally, both percutaneous nephrolithotomy and ureteroscopic stone removal have been established in children as safe and effective treatment options. This gives the clinician the opportunity to choose from a wide range of treatment alternatives, including open surgery, and only this approach will ensure 100% stone removal in individual patients along with the prevention of recurrence and, thus, the elimination of long-term morbidities in this vulnerable patient population.

Side effects of high-energy shockwaves in the human kidney: first experience with model comparing two shockwave sources

The side effects of high-energy shockwaves (HESW) from two different sources on kidney parenchyma obtained from 10 patients treated by radical nephrectomy for renal cell carcinoma were examined. Immediately after nephrectomy, the kidneys were perfused with cold HTK solution and kept in hypothermia (8 degrees C) for a maximum of 4 hours. In five cases, the tumor-free parenchyma was treated at the upper or lower renal pole with 2000 shocks, energy output 21 kV, in an experimental electromagnetic shockwave system (Siemens Co., Erlangen). In the other five cases, the upper or lower poles were treated with 2000 shocks, energy output 24 kV, in an electrohydraulic spark gap system (MFL 5000; Dornier Medizintechnik, Germering). The resulting tissue defects were analyzed by histologic examinations. Changes after treatment with the electromagnetic system were found mainly in the tubules and midsized blood vessels in a well-defined focal area. Treatment with the electrohydraulic system was followed by tubular and glomerular lesions combined with vessel defects in a patchy pattern. The model is able to define the side effects of HESW in the human kidney and to test the side effects of different lithotripters.

Effects of extracorporeal shockwave lithotripsy on urinary concentration of epidermal growth factor

In a prospective study, we tried to determine whether extracorporeal shockwave lithotripsy (SWL) has any effect on urinary epidermal growth factor (EGF) concentrations and to investigate whether EGF can be used as a marker for detecting shockwave-induced impairment of distal tubular cells. A total of 12 patients with renal pelvic or caliceal stones < or = 2 cm undergoing anesthesia-free SWL without ancillary measures and a control group of 10 patients without any urologic symptoms were included in this study. The urinary concentrations of EGF were measured by radioimmunoassay before and 4 hours, 24 hours, and 7 days after SWL. Relative urinary EGF concentrations were expressed as the ratio of EGF to creatinine (ng/mL creatinine). The mean urinary EGF concentration (mean +/- standard error) in control subjects and patients with renal pelvic or caliceal stones before SWL was 23.90 +/- 3.15 ng/mL creatinine and 22.18 +/- 6.85 ng/mL creatinine, respectively (p > 0.05). In patients with stones, we found a decrease in urinary EGF concentration 4 hours, 24 hours, and 7 days after SWL. Indeed, 7 days after SWL, the EGF concentration was on average half of the original value, a biologically significant, although not statistically significant, decrease.

Effect of extracorporeal shock wave lithotripsy on glomerular and tubular functions

To evaluate the early and late effects of extracorporeal shock wave lithotripsy on renal function, we prospectively designed a controlled study using a Direx lithotriptor. Twenty-five patients with renal stones and 16 healthy volunteers as the control group were included in the study. Blood and urine samples were collected before and after 24 hours, seven days and 8 months in the patient group. White blood cell count, serum levels of haemoglobin, urea, creatinine, SGOT, SGPT, AP, and LDH were determined. 24-hour urine specimens were collected to be tested for volume, excretion of creatinine, albumin, N-acetyl-beta-glucosaminidase, gamma-glutamyltransferase and beta-2-microglobulin. There were statistically significant increments in the secretion of urinary enzymes and albumin in the early period after ESWL, no longer lasting 8 months after the procedure. At 8 months one patient was hypertensive as judged by the diastolic pressure above 95 mm Hg. The results of this study showed that, although there was a transient glomerular and tubular damage after extracorporeal shock wave lithotripsy, the procedure seems safe and causes no permanent deterioration in renal function.

Leucine aminopeptidase enzymuria: quantification of renal tubular damage following extracorporeal shock wave lithotripsy

To evaluate the extent of renal parenchymal injury following high energy shock wave (HESW) application we measured the urine levels of two renal tubular brush border enzymes: leucine aminopeptidase (LAP) and gamma-glutamyltranspeptidase (GGT) the day before, 24 hours and 7 days after extracorporeal shock wave lithotripsy (ESWL) in 23 patients. All patients had caliceal stones and were treated with a Dornier MPL 9000 lithotriptor under sedoanalgesia. Creatinine concentration of each sample together with total shock wave effect (TSWE) values were also assessed and comparatively evaluated with enzymuria levels. Our results indicated a statistically significant rise in urinary excretion of both enzymes after 24 hours following lithotripsy (p < 0.05). All these values returned to normal limits within 7 days after ESWL (p > 0.05). Transient tubular damage due to HESW was found to be related to TSWE values assessed in our group.

Mechanisms of shockwave action in the human kidney

The effects on the human kidney parenchyma of high-energy shockwaves (HESW) with different energy densities were examined. Kidneys of patients treated by radical nephrectomy for renal cell carcinoma were perfused with cold HTK solution immediately after nephrectomy and kept in hypothermia (8 degrees C) for a maximum of 4 hours. The tumor-free parenchyma was treated with 2000 shocks at energy outputs of 15 kV (16 MPa, 0.15 mJ/mm2), 17 kV (32 MPa, 0.25 mJ/mm2), 19 kV (50 MPa, 0.4 mJ/mm2), and 21 kV (65 MPa, 0.6 mJ/mm2) in an experimental electromagnetic shockwave system (Siemens Co., Erlanger, Germany). Resulting tissue effects were analyzed by histologic and immunohistochemical examinations and confocal laser scanning microscopy. Different sensitivities of cell components, blood vessels, and tubules were found. Laser scanning microscopy revealed nuclear alterations in the vicinity of the focus up to a distance of approximately 10 mm. Severe histologic changes were found in a smaller zone, while immunohistochemistry studies revealed negative collagen IV staining in an area of approximately 4 x 4 mm (all distances measured within the plane perpendicular to the acoustic axis). From these results, it can be concluded that HESW directly damage the tubules and the vascular system, which might explain the clinical changes after extracorporeal shockwave lithotripsy in human patients. The extent of these effects seems to be dependent on the applied energy.

Pediatric urolithiasis: review of research and current management

The treatment of urolithiasis in children has changed dramatically in recent years. With the proven safety and efficacy of extracorporeal shock wave lithotripsy (ESWL), percutaneous lithotripsy and ureteroscopy in adults, these modalities are now in the forefront of the treatment of pediatric urinary stones. Our research in the juvenile non-human primate with ESWL indicates that renal damage in most cases is neither significant or persistent. In addition, technological advances in instrumentation have cleared the way for the use of percutaneous lithotripsy and ureteroscopy in most pediatric patients. Today, open surgical procedures for stone disease in children should be a last resort.