Primary Hyperoxaluria

Oxalate nephropathy may be a growing threat to kidney health

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Oxalate nephropathy (ON), characterized by the deposition of calcium oxalate crystals in the kidneys, is a serious and often underrecognized condition with significant morbidity and mortality, according to a study that found that ON commonly presents as acute kidney injury (AKI) or acute on chronic kidney disease (CKD), with a poor prognosis.

Primary Hyperoxaluria is one of the causes of ON. Primary Hyperoxaluria is a rare genetic disorder characterized by the overproduction of oxalate, leading to the formation of calcium oxalate crystals in the kidneys and other organs.

Out of 60 native biopsies with oxalate deposits, 31 patients with clinically significant findings were identified and described.

Among the identified patients, 87.1% had hypertension, 58.1% had diabetes, 42% had nephrolithiasis, and 77.4% had underlying CKD with a mean baseline creatinine of 1.8 mg/dL. The mean creatinine at biopsy, however, spiked to 5.2 mg/dL, underlining the severity of the condition.

Kidney biopsies unveiled abundant calcium oxalate crystal deposits, accompanied by additional diagnoses in 27 out of 31 cases. The most common coexisting conditions were acute tubular injury (54.8%) and diabetic glomerulosclerosis (22.6%). Severe and moderate interstitial fibrosis were present in 38.7% and 51.6% of biopsies, respectively.

The study discovered diverse etiologies of ON, with 10 patients having a single cause, 10 presenting multifactorial factors (including enteric hyperoxaluria and high precursor intake), and 11 cases with unclear origins. Only 7 patients had a history of gastric bypass.

The mean follow-up duration was 26.8 months, during which 21 patients required dialysis, and 12 patients (38.7%) died. Of the 26 patients with follow-up data exceeding 1 year, 17 received targeted management, while the remaining 9, who did not receive targeted treatment, all required hemodialysis.

The study noted a significant increase in vitamin C intake post-COVID pandemic (2020-2023), with 31.6% of patients reporting consumption, compared to 16.7% before 2020.

Llanos M, Kwon A, Herlitz L, et al. The Clinical and Pathological Characteristics of Patients with Oxalate Nephropathy. Kidney360. 2023;doi: 10.34067/KID.0000000000000340. Epub ahead of print. PMID: 38095544.