Kidney Failure Risk Linked to Oxalate Excretion

SAN DIEGO—Higher baseline 24-hour urinary oxalate excretion among patients with chronic kidney disease (CKD) is associated with an elevated risk of end-stage renal disease (ESRD) and CKD progression, researchers reported at the American Society of Nephrology’s Kidney Week 2018 conference.

In a study of 3123 participants in the Chronic Renal Insufficiency Cohort (CRIC) study with median baseline eGFR of 43 mL/min/1.73m², patients in the highest quintile of oxalate excretion (27.5–102.1 mg/24h) had a 41% higher adjusted risk of ESRD and 28% higher adjusted risk of CKD progression compared with those in the lowest quintile (1.4–11.5 mg/24h), according to a team led by Sushrut S. Waikar, MD, of Harvard Medical School in Boston. The investigators adjusted findings for age, sex, race/ethnicity, baseline estimated glomerular filtration rate (eGFR), diabetes, body mass index, systolic blood pressure, hemoglobin level, serum albumin level, and medications.

The study population had a median baseline eGFR of 43 mL/min/1.73 m² and a median 24-hour oxalate excretion of 18.6 mg.

The findings, if confirmed in other studies, could lead to more widespread screening for occult hyperoxaluria in patients diagnosed with CKD. The findings may also stimulate studies looking at whether lowering oxalate excretion could be a therapeutic strategy to preserve kidney function in CKD, Dr Waikar said.

In an interview with Renal & Urology News, Dr Waikar said he became interested in oxalate excretion in CKD after diagnosing oxalate nephropathy in a long-term patient who had a typical case of CKD that he thought was due to hypertension. “She developed progressive kidney failure requiring dialysis, and we biopsied her due to the remote possibility of a drug-induced interstitial nephritis from a new cancer chemotherapy drug,” Dr Waikar related. “After finding oxalate nephropathy on her biopsy, I asked myself whether it might be more common than we suspect, especially in patients with presumed hypertension-associated kidney disease or diabetic nephropathy.” Based on this clinical experience and after reviewing the literature on primary hyperoxaluria and oxalate toxicity, Dr Waikar wrote a grant application to measure 24-hour urine among CRIC study participants.

Reference

Waikar SS, Lieske JC, Xie D, et al. Urinary oxalate excretion and the risk of ESRD and CKD progression. Data presented at the American Society of Nephrology’s Kidney Week 2018 conference in San Diego, Oct. 23-28. Abstract TH-OR082.

From the December 01, 2018 Issue of Renal and Urology News