Urinary stones and kidney failure: treat both aggressively!

STONES IN AN ESTABLISHED CKD, DO WE PROCEED?

Dr Clarence Lei Chang Moh,

Consultant Urologist, Kidney & Stone Centre, Normah Hospital, Kuching.

CKD, chronic kidney disease, is diagnosed when there is kidney disease for more than 3 months, structural or biochemical.  There are 5 stages of CKD, with Stage 5 as creatinine clearance less than 15 mls/min. A patient is  likely to have CKD rather than acute kidney disease if he  has risk factors of diabetes, hypertension, increased age, low haemoglobin, low calcium, high phosphate, high PTH.  Ultrasound show echogenic and smaller kidneys unless the patient has diabetes or lymphoproliferative disease. 

Obstructive uropathy can be readily relieved by percutaneous nephrostomy or ureteric stenting, rather than dialysis.  Other indications for stone treatment in CKD include pain from obstruction and infection.  Even patients who need chronic dialysis should undergo stone treatment to maintain urine output such that the patient can enjoy fluid for some months.

Radiolucent uric acid stones can be treated by chemodissolution, once the obstruction has been relieved by ureteric stenting. The side with the “easier” stone can be treated first to allow some recovery of renal function.  Otherwise, the kidney with the better function (good renal size, cortex with less echogenicity) can then be operated.  Upper urinary tract stones less than 2 cm can be readily treated by ESWL, extracorporeal shockwave lithotripsy. 

Stone free rates after treatment are reduced in patients with CKD.  This may partly be related to the lower urine volume in patients with CKD.  In one study of ESWL for proximal ureteric stones, the stone free rate was 50% when the GFR was less than 60 as compared to 93% when the GFR was more than 60.  Therefore, the urologist must be inclined to do more axillary procedures when treating patients with CKD.

Patients who have nephrectomy for stones are more likely to develop CKD as compared to patients who had kidneys preserved.  In the Sarawak General Hospital, 36% of 71 nephrectomies over 32 months were done for stones with infection (reported in MUC 2012).   Uric acid and struvite stones have worse CKD compared to calcium stones (eGFR 55 vs 72).  Hence, stone analysis is important to stratify risk.  Urinary stones per se has a 2 times increased risk of CKD (1% vs 0.5%) even after adjustment for confounders (e.g. age, diabetes, hypertension), even after successful ESWL, and even after a single stone episode.  The basis may be genetic whereby a defect contributes to CKD and  stone formation.  Therefore, stone formers should only donate their kidneys after due consideration.

Managing patients with CKD is teamwork with the nephrologists, nurses, dietitians and the family.  Stones presenting with renal impairment may require urgent treatment e.g. haemodialysis for fluid overload, hyperkalaemia or restlessness due to severe uraemia. Management of stone & CKD includes management of underlying diabetes, hypertension, anaemia, gout and bone disease. According to the Malaysian National Renal Registry data (www.msn.org.my) 1-2 % (data 1993-2013) of renal failure in Malaysian is due to urinary stones whereas it is 0.2% in the US Renal Data System in 2011.

CONCLUSION: Every effort must be made to treat urinary stones especially in CKD. Axillary procedures e.g. ureteric stenting and aggressive medical measures should be implemented in treating stones with CKD.

Lecture given at Malaysian Urological Conference 2014