Calculi in renal transplants

Renal transplantation in cats with calcium oxalate urolithiasis: 19 cases (1997–2004)

OBJECTIVE

To determine outcome of renal transplantation in cats with renal failure associated with calcium oxalate urolithiasis.

DESIGN

Retrospective case series.

ANIMALS

19 cats.

PROCEDURE

Medical records were reviewed for evaluation of signalment, preoperative clinical signs, physical examination results, dietary history, clinicopathologic data, abdominal imaging, postoperative diet, complications, and long-term outcome.

RESULTS

The domestic shorthair was the most common breed represented. There were 13 spayed females and 7 castrated males. Mean age was 6.8 years. Clinical signs included weight loss, lethargy, vomiting, anorexia, polyuria, and polydipsia. Before surgery, cats received commercially available canned or dry food (n = 10), a prescription renal failure diet (5), a commercial diet to manage struvite crystalluria (1), or an unknown diet (3). Seventeen cats were anemic. All cats were azotemic. Hypercalcemia was detected in 7 cats. Abdominal imaging revealed nephrolithiasis, ureterolithiasis, or both in all cats. Median duration of survival of all cats was 605 days. Eight cats were alive 282 to 2,005 days (median, 1,305 days) after surgery. Eleven cats died 2 to 1,197 days (median, 300 days) after surgery. Five cats formed calculi in their allograft (120 to 665 days). Two of the 5 cats that formed calculi were hypercalcemic. Four of the 5 cats died following complications associated with formation of calculi.

CONCLUSIONS AND CLINICAL RELEVANCE

Renal transplantation appears to be a viable option for cats in renal failure secondary to calcium oxalate urolithiasis. In addition to reported complications in renal transplant recipients, formation of calculi within the allograft may also occur.

Urinary stones following renal transplantation

BACKGROUND

The formation of urinary tract stones following renal transplantation is a rare complication. The clinical features of stones after transplantation differ from those of non-transplant patients. Renal colic or pain is usually absent and rarely resembles acute rejection.

METHODS

We retrospectively studied 849 consecutive kidney transplant patients in The Rogosin Institute/The Weill-Cornell Medical Center, New York who were transplanted between 1980 and 1997 and had functioning grafts for more than 3 months, to determine the incidence of stone formation, composition, risk factors and patient outcome.

RESULTS

At our center, urinary stones were diagnosed in 15 patients (1.8%) of 849 functioning renal grafts for 3 or more months. Of the 15 patients, 10 were males and 5 were females in their third and fourth decade. Eight patients received their transplant from living donors and 7 from cadaveric donors. The stones were first diagnosed between 3 and 109 months after transplantation (mean 17.8 months) and 5 patients had recurrent episodes. The stones were located in the bladder in 11 cases (73.3%), transplanted kidney in 3 cases and in multiple sites in one case. The size of stones varied from 3.4 mm to 40 mm (mean 12 mm). The composition of stones was a mixed form of calcium oxalate and calcium phosphate in 5 cases and 4 patients had infected stones consisting of struvite or mixed form of struvite and calcium phosphate. Factors predisposing to stone formation included tertiary hyperparathyroidism (n = 8), hypercalciuria (n = 5), recurrent urinary tract infection (n = 5), hypocitraturia (n = 4), and obstructive uropathy (n = 2). Many cases had more than one risk factor. Clinically, painless hematuria was observed in 6 patients and dysuria without bacteriuria in 5 patients. None had renal colic or severe pain at any time. There were no changes in graft function at diagnosis and after removal of stones. Five patients passed stones spontaneously and 8 patients underwent cystoscopy for stone removal.

CONCLUSION

Urinary stone formation following kidney transplantation is a rare complication (1.8%). Hyperparathyroidism, hypercalciuria, recurrent urinary tract infection and hypocitraturia are the most common risk factors, but often there are multiple factors which predispose to stone formation. To detect stones and determine their location and size, ultrasonography appears to be the most useful diagnostic tool. Prompt diagnosis, the removal of stones and stone-preventive measures can prevent adverse effects on renal graft outcome.

[Incidence and treatment of urinary lithiasis in renal transplantation]

INTRODUCTION

Urinary calculi is an uncommon complication in kidney transplantation; several stone risk factors are found in transplanted patients, but in most cases there is not a relationship between these risk factors and stone formation. The treatment of these patients is complex due to their both immunosuppressive status and border-line renal function.

MATERIAL AND METHOD

From 1980 to February 2000, 1198 kidney transplant have been performed in our institution. We describe our series consisting in 22 urinary calculi (15 in the graft, 3 in the urether and 4 in the bladder) in 18 patients, including 7 stones detected in cadaveric donor patients.

RESULTS

We performed external shock wave lithotripsy in 7 patients, bench surgery in 4, endoscopic mechanic lithotripsy in 5, open surgery in 1 and observation in 6. Calcium oxalate (mono and dihidrate) was found in 9 of 13 calculi. Metabolic changes were found in 15 of the 18 patients, the most common was hiperuricemia. There were not complications of every treatment applied and 9% of them needed a savage treatment. We found recurrence in 4 cases (22.2%). Now 12 of the patients are stone-free (66.7%) and three have non-significative stones (83.3% without symptoms).

CONCLUSIONS

Detection of renal calculi in cadaveric renal donors is not a reason to refuse the graft for further transplantation. In both renal calculi up to 2 cm and uretheric calculi surgical treatment is assessed as first option. In caliceal stones smaller than 5 mm observations is the best treatment.

Risk factors for calculus formation in patients with renal transplants

OBJECTIVE

To investigate the risk factors for stone formation in patients with functioning renal transplants in whom renal calculi develop.

PATIENTS AND METHODS

Renal calculi developed in six of 178 patients with functioning renal transplants under current review, an incidence of 3%. Risk factors for stone formation were investigated in five of these patients and compared with a randomly selected control group of 41 transplant patients with no stone problems.

RESULTS

Patients with transplant calculi typically passed smaller volumes of significantly more concentrated and alkaline urine with greater urinary excretion of uric acid (P < 0.05). Urine calcium excretion was also increased. Crystalluria was present in three of five stone formers compared with two of 25 controls. Overall, metabolic abnormalities included hypocitraturia (75%), hyperparathyroidism (36%), hypophosphataemia (24%) and hypercalcaemia (10%). Urinary infection was common (50%) and urinary output of magnesium and phosphate was at the lower end of normal for all patients.

CONCLUSION

These results suggest a multifactorial aetiology for stone formation in renal transplant recipients. Approaches to prevention and management are discussed.

Extracorporeal shock-wave lithotripsy in transplanted kidney

Urolithiasis is the least described urologic sequela of renal transplantation. We describe a renal transplant patient who presented with painless gross hematuria. An intravenous pyelogram demonstrated a 4 x 7-mm calculi in the region of the ureteropelvic junction, causing moderate hydronephrosis. The patient was treated successfully with extracorporeal shock-wave lithotripsy (ESWL). Serum creatinine and twenty-four-hour creatinine clearance were unchanged from levels prior to ESWL.

Percutaneous nephrolithotomy in transplanted kidney

Renal transplant patients with urologic complications can be managed safely with percutaneous techniques. The development of renal calculi in transplanted kidneys is uncommon, but in these cases complications such as infection and urinary tract obstruction with impairment of graft function can occur. We report 2 cases managed successfully with percutaneous nephrolithotomy.

Percutaneous stone and stent removal from renal transplants

Techniques developed for removal of stones from normally sited kidneys can be safely employed in the transplanted kidney. We describe our experience in removing stones, stent material and organised blood clot from renal transplant collecting systems, using modified percutaneous techniques.

Calculus formation in renal transplant patients

Of 149 renal transplants performed between May 1965 and December 1980 a stapled ureteroureterostomy was done in 112 (75 per cent) using a commercially available stapling device. Calculus developed in 7 patients (6.3 per cent) in whom this technique was used, with the interval between transplantation and calculus formation being 13 months to 6 years. We conclude that the stapled ureteroureterostomy should be reserved for special instances, such as a short donor ureter or when the correction of urological complications demands a rapid ureteroureterostomy.

Stones in renal transplants

In a 50-year-old man (case 1) and a 17-year-old girl (case 2) stones developed in a functioning renal transplant. The respective intervals from transplantation to appearance of stone were seven years and six months. The serum calcium was elevated to approximately 3.00 mmol/l in case 1 and 2.65 mmol/l in case 2. The concentration of parathyroid hormone in serum was increased in case 1. Subtotal parathyroidectomy was performed in both patients, with removal of 2550 mg (case 1) and 150-160 mg (case 2) parathyroid tissue. In case 2 slight hypercalcaemia reappeared two months later. When stones in a transplanted kidney are associated with only slight hypercalcaemia and there is no deterioration of the renal function, conservative measures to reduce the serum calcium should be tried before subtotal parathyroidectomy is undertaken.

Urolithiasis after kidney transplantation--clinical and mineralogical aspects

Urolithiasis is a rare complication following kidney transplantation. Experience with this complication in 6 of 426 transplantations performed from 1968 to 1979 is reviewed. The clinical symptoms are different from the disease in non-transplant patients. Three major predisposing causes for the development of calculi after kidney transplantation were found in our patients--urodynamic disorders following complications of the ureterovesical anastomosis, persistent bacteriuria and renal tubular acidosis and, less importantly, the presence of hypercalcemia and hypercalciuria as a result of secondary hyperparathyroidism. Crystal-optical and x-ray-diffraction studies contributed to the interpretation of the constituents and texture of the calculi and of the aetiological factors concerned.