Increasing the energy dose applied per session through increasing the number of shock waves in extracorporeal lithotripsy: a prospective and comparative study: Beyond the Abstract

The increased energy applied during each session not only constituted an effective therapeutic modification, but additionally, it showed that neither the risk nor severity of the complications increased when compared to the standard strategy, having a similar safety profile to that of the standard treatment. 

As an additional element to support our hypothesis, the evolution of a series of widely established markers indicating renal damage were analyzed in a subgroup of patients in our study.

A subset of 33 patients were consecutively selected prior to the allocation, of which 27 were completed follow-up for three months and analyzed. In these patients, some renal damage indicators were determined for blood and urine at three stages (before treatment, 48 hours after treatment and within a week of the treatment). These markers were: protein neutrophil gelatinase-associated lipocalin (NGAL), Interleukin-6 (IL-6) and microalbuminuria/creatinine ratio: 

  • The NGAL protein is a recent and promising non-invasive indicator of kidney damage, characterized by its sensitivity. It plays a protective role at the renal level, representing the tubular resurfacing after an ischemic attack, and its levels rise before those of the creatinine do (1). 
  • IL-6 is a proinflammatory cytokine which increases the mesangial proliferation after a glomerular attack, and its persistent elevation is a characteristic finding in chronic kidney disease.
  • Any renal aggression can cause the appearance of proteinuria, in which the 24-hour urine measuring has been replaced in clinical practice by the identifying of albuminuria in simple urine samples. The ratio with respect to the levels of creatinine compensates for the hydration status of the patient (2).  Microalbuminuria rises sharply at 24 hours of the treatment, normalizing around the fourth day. Chronic renal disease has shown to be a risk marker even in patients with a relatively normal glomerular filtration (3).
To avoid potential bias in the results, those patients with poorly controlled hypertension, active urinary tract infection, and previously advanced chronic renal disease (Cr> 2mg/dl), active malignancy and the intake of nephrotoxic drugs during the seven days prior to any determinations were excluded from this sub-analysis.

There were no differences in the kinetic values of elevation and decline in either of the groups with respect to their previous baseline levels respect to NGAL and micrioalbuminuria/creatinine ratio.

In our series, IL-6 was the only marker that demonstrated transiently a greater elevation in the group receiving extended treatment (tables 1 and 2).

  Group A (48h) Group B (48h) p
Interleukina-6 1,3 2,15 0,03
Albumin/Creatinine 1,5 1,38 0,25
NGAL 2,4 1,89 0,45
 Table 1. Proportional increase in baseline value of the markers of renal damage 48h after treatment.

  Group A (7 d) Group B (7 d) p
Interleukina-6 1,76 1,25 0,65
Albumin/Creatinine  0,63 0,68 0,23
NGAL 2,9 2,45 0,27
  Table 2. Proportional increase in baseline value of the markers of renal damage 7 days after treatment.

So, in conclusion, these results confirmed the clinical safety profile obtained in our study of increasing the energy applied through increasing the number of shockwaves in extracorporeal shock wave lithotrypsy. 

Written by: López-Acón JD; Budía A, Bahílo MP, Trassierra M, Conca MLÁ, Ordaz GJ, Boronat F.
J Endourol. 2017 Oct 19. doi: 10.1089/end.2017.0261. [Epub ahead of print]

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References
1 Zekey F, Senkul T, Ates F, et al. Evaluation of the impact of shock wave lithotripsy on kidneys using a new marker: how do neutrophil gelatinese-associated lypocalin values change after shock wave lithotripsy? Urology. 2012 Aug;80(2):267-72

2 Bakker AJ. Detection of microalbuminuria. Receiver operating characteristic curve analysis favors albumin-to-creatinine ratio over albumin concentration. Diabetes Care. 1999 Feb;22(2):307-13.

3 Hemmelgarn BR, Manns BJ, Lloyd A, et al. Alberta KidneyDisease Network. Relation between kidney function, proteinuria, and adverse outcomes. JAMA. 2010 Feb 3;303(5):423-9.