The Case | Acute renal failure and a "rejuvenating powder"

Dietary Supplement Safety in Older Adults: A Review of Published Case Reports

Objective: This review summarizes recent case reports where the consumption of dietary supplements by older adults may have caused an adverse event. Data Sources: In December 2023, PubMed was surveyed for case reports published from 2000 onwards, using two medical subject heading (MeSH) terms, "aged" and "dietary supplements," where the latter was combined with the MeSH subheadings "adverse effects," "poisoning," or "toxicity." Major clinical trials for dietary supplements were identified at ClinicalTrials.gov, an online database of clinical research studies, or in PubMed, and screened for information on adverse effects. Data Synthesis: The described search strategy yielded 820 publications, including 122 case reports, which were then manually screened for relevant and informative case reports involving dietary supplements and people 65 years of age or older. Consequently, 41 publications were selected describing 46 individual case reports. Etiologies of adverse events included interactions of dietary supplements with prescribed medication, ingestion of higher-than-intended or instructed supplement doses, intake of the same supplement from multiple sources, and supplement contamination. Prominent adverse events encompassed hypercalcemia (vitamin D), thyroid test interference (vitamin B7), neuropathy (vitamin B6), oxalate nephropathy (vitamin C), and interactions with warfarin therapy (vitamins E and K, and omega-3 fatty acids). Conclusion: Health care practitioners are advised to consider dietary supplements as contributors to adverse clinical symptom presentations, while patients are encouraged to provide current records of their prescribed medications and dietary supplements to their health care providers. This is particularly important for older adults where both medication intake and supplement consumption are high.

Pathophysiology and Management of Hyperoxaluria and Oxalate Nephropathy: A Review

Hyperoxaluria results from either inherited disorders of glyoxylate metabolism leading to hepatic oxalate overproduction (primary hyperoxaluria), or increased intestinal oxalate absorption (secondary hyperoxaluria). Hyperoxaluria may lead to urinary supersaturation of calcium oxalate and crystal formation, causing urolithiasis and deposition of calcium oxalate crystals in the kidney parenchyma, a condition termed oxalate nephropathy. Considerable progress has been made in the understanding of pathophysiological mechanisms leading to hyperoxaluria and oxalate nephropathy, whose diagnosis is frequently delayed and prognosis too often poor. Fortunately, novel promising targeted therapeutic approaches are on the horizon in patients with primary hyperoxaluria. Patients with secondary hyperoxaluria frequently have long-standing hyperoxaluria-enabling conditions, a fact suggesting the role of triggers of acute kidney injury such as dehydration. Current standard of care in these patients includes management of the underlying cause, high fluid intake, and use of calcium supplements. Overall, prompt recognition of hyperoxaluria and associated oxalate nephropathy is crucial because optimal management may improve outcomes.

Etiologies, Clinical Features, and Outcome of Oxalate Nephropathy

Background

Oxalate nephropathy is a potentially underestimated cause of kidney failure characterized by massive deposition of calcium oxalate crystals in the renal parenchyma. The prevalence and modes of presentation of this entity are ill-defined.

Methods

Here we report on the largest consecutive series of cases of adult oxalate nephropathy diagnosed on native kidney biopsies from January 2010 to December 2018 in the UCLouvain Kidney Disease Network.

Results

We screened 2265 native kidney biopsies and identified 22 cases (1%) of oxalate nephropathy. Patients had a mean age at diagnosis of 61 years (±20) and presented either with acute on chronic kidney disease (CKD) (62%) or with acute kidney injury (AKI) (38%). Mean serum creatinine at biopsy was 8.0 ± 4.5 mg/dl. Kidney biopsies showed abundant calcium oxalate crystal deposits, associated with acute interstitial nephritis and tubular necrosis, and variable degrees of interstitial fibrosis and tubular atrophy. Chronic pancreatitis and gastric bypass were the most common causes of oxalate nephropathy (48%). During a mean follow-up of 29 months, half of the patients (52%) progressed to kidney failure, all within the month following diagnosis. Higher serum creatinine level at presentation and interstitial fibrosis and tubular atrophy score were associated with progression to kidney failure.

Conclusion

Oxalate nephropathy is the cause of kidney disease in 1% of consecutive native kidney biopsies and typically presents as acute on CKD or AKI. The prognosis of the disease is poor, with a high rate of kidney failure within the first month after the diagnosis.