S4124 Obesity-Associated Secondary Hyperoxaluria and Nephrolithiasis in a Patient With Non-Alcoholic Fatty Liver Disease

Introduction: Obesity is a well-known risk factor for a range of metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). However, its role in rarer conditions like secondary hyperoxaluria and nephrolithiasis is often overlooked. This case highlights the rare occurrence of secondary hyperoxaluria-induced nephrolithiasis in a patient with obesity and NAFLD, emphasizing the need for comprehensive dietary management. Case Description: A 38-year-old obese Hispanic woman with a body mass index of 38 kg/m² and a medical history of type 2 diabetes, hypertension, and NAFLD who presents with chronic flank pain, dysuria, and fatigue. Despite her diagnosis, she had poor adherence to lifestyle modifications and a diet high in refined sugars, processed foods, and oxalate-rich items like spinach and nuts. She also reported minimal physical activity. Laboratory tests revealed elevated liver enzymes (ALT 102 U/L, AST 95 U/L) and a hemoglobin A1C of 8.5%. Urinalysis showed microscopic hematuria. A 24-hour urine collection revealed oxalate levels of 70 mg/24 hours (normal <45 mg/24 hours), confirming secondary hyperoxaluria. Computed tomography imaging showed bilateral renal stones, with 1 obstructing the left renal pelvis. The patient was diagnosed with secondary hyperoxaluria-induced nephrolithiasis, exacerbated by her obesity and diet. The patient was referred for dietary counseling and advised to reduce high-oxalate foods and increase fluid intake. A Mediterranean diet was recommended, focusing on whole grains, fruits, vegetables, lean proteins, and healthy fats, while limiting oxalate-rich foods. She was also encouraged to increase physical activity and aim for a weight loss of 5-10% to improve metabolic parameters and reduce kidney stone formation. At a 6-month follow-up, the patient had lost 8% of her body weight. Her liver enzymes decreased (ALT 68 U/L, AST 58 U/L), and her hemoglobin A1C dropped to 7.4%. Repeat urine analysis showed a reduction in oxalate excretion to 45 mg/24 hours. Her kidney stones remained stable without further complications, and she reported reduced flank pain and improved energy levels. Discussion: Obesity alters gut microbiota, calcium absorption, and oxalate metabolism, increasing hyperoxaluria and nephrolithiasis risk. Secondary hyperoxaluria, often seen in genetic disorders, can occur in obese patients with poor diet. This case highlights the importance of dietary interventions, weight management, and the Mediterranean diet to prevent complications and improve outcomes.