Saxena S et al, 2013: Treating stones in transplanted kidneys
Saxena S, Sadideen H, Goldsmith D
Department of Nephrology and Transplantation, Guy's and St. Thomas' NHS Foundation Trust, London, UK
The formation of calculi in renal allografts is an uncommon complication in renal transplant recipients, with a reported incidence of 0.2-1.7% according to retrospective studies. Although the majority of these stones appear to form de novo following renal transplantation (RTX), there is a growing body of evidence suggesting that more often than previously thought they may be transplanted with the donor graft itself. The etiology and pathophysiology of renal graft stones is multifactorial. A combination of metabolic and urodynamic factors predispose to stone formation and these are generally found more frequently in allograft rather than native kidneys. In addition tertiary hyperparathyroidism (following RTX) plays an important role. Renal allograft stones can pose significant challenges for the clinician. The diagnosis requires a high index of suspicion and must be prompt, as these patients' reliance on a solitary kidney for their renal function leaves them susceptible to significant morbidity. However, reports in the literature come largely from anecdotal experience and case reports, meaning that there is a limited consensus regarding how best to manage the condition. We suggest that interventional treatment should be guided primarily by stone size and individual patient presentation. Good outcomes have been reported with shockwave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL) and ureteroscopy, but optimal management of the risk factors leading to calculi formation (i.e., prevention) will remain the most cost-effective management.
Minerva Med. 2013 Feb;104(1):31-40
PMID:23392536 [PubMed - in process]
This review is of great interest because dealing with stones in transplanted kidneys is a difficult and delicate clinical problem. Great care is necessary in order to avoid worsening of the renal function due to damage of the renal parenchyma as a result of the stone removing procedure as well as to avoid complications by stones present in the kidney. The authors of this literature review also conclude that there is an increasing tendency to accept for transplantation kidneys with concrements. In these patients stone clearance should ideally be carried out before or during transplantation, but that is not always possible or successful. In some patients the presence of concrements might also have been overlooked.
Non-invasive or low-invasive endoscopic procedures should be used whenever possible and the recommendation given, based on the literature review, is to use SWL for stones with diameters 5 mm should be considered for stone elimination as early as possible.
It has been my own routine when treating patients with stones in transplanted kidneys to pre-treat them with some antioxidant / radical scavenger, for instance allopuriol, as an attempt to counteract tissue damage. Moreover, when uric acid stones have formed medical dissolution should be the method of choice.