Characteristics of Patients with Enteric Hyperoxaluria

Background: Enteric hyperoxaluria (EH) is a condition characterized by oxalate (Ox) overabsorption in the digestive tract leading to increased renal excretion. It predisposes patients to recurrent kidney stones, nephrocalcinosis, & progressive kidney impairment w/ severe cases requiring renal replacement therapy. Management remains a challenge due to heterogeneity of underlying etiologies, lack of standard laboratory cut-offs for the development of its consequences, & individual treatment responses. Methods: We conducted a retrospective cohort study of 40 patients enrolled in the EH Registry at NYU Langone Health w/ an aim to contribute to the understanding of EH. Through comprehensive chart review, the study explores demographic characteristics including age, gender (male (M) vs. female (F)), EH etiology, eGFR & interventions including calcium (Ca) supplement & potassium (K) citrate. A cross-section analysis of 24-hour urinary collections was conducted (Table 1). Results: The cohort comprised 40 patients w/ EH (50% M, 50% F) w/ a mean age of 59 (58 M, 61 F). Etiologies were Crohn's disease (40%), Roux-en-Y gastric bypass (12.5%), pancreatic insufficiency (25%), and short bowel syndrome (22.5%). Patients had eGFR >60 ml/min (70%), 45-59 (10%), 30-44 (10%), 15-29 (5%), <15 (2.5%), & unknown (2.5%). For intervention, 32.5% were on K citrate, 57.5% w/ history of K citrate use, and 22.5% were on Ca supplements. Urine collections showed significant risk for recurrent CaOx stones w/ high Ox & CaOx supersaturation (SS). Conclusion: This cohort includes patients w/ mild to moderate CKD. Crohn's disease was the most common etiology. Significant gender differences were observed in urinary profiles in EH patients, w/ M showing higher Ox & SS CaOx despite higher volumes & citrate. Supplementation w/ citrate & Ca are used by a significant portion of this cohort but did not alleviate significant risk of stone recurrence or progressive CKD. Table 1. 24-hour Urinary Profile - M (n=20) (mean/SD) F (n=20) (mean/SD) Volume (L/d)* 2.46(0.96) 1.75(0.92) SS CaOx (L/d) 13.67(76.70) 12.51(42.95) Ox (mg/d) 74.96(64.62) 59.26(36.64) Ca (mg/d)* 137.08(118.28) 80.90(58.06) Citrate (mg/d)* 426.74(274.99) 288.84(284.23) pH 6.38(5.55) 6.21(0.78) Sodium (mmol/d) 187.29(70.88) 125.10(74.02) *p<0.01