Anemia and End-Stage Renal Disease: How a Wealth of Wisdom (And Crystals) Led to an Unusual Diagnosis

Abstract Hyperoxaluria is a rare disease state characterized by increased amounts of oxalate depositing in the kidneys. The causes of hyperoxaluria can be further divided into primary hyperoxaluria, where there is a genetic enzymatic deficiency leading to an overproduction of oxalate and secondary hyperoxaluria, where either intestinal disorders or increased dietary forms of oxalate are consumed, leading to increased oxalate concentrations. Hyperoxalosis occurs when concentrations of calcium oxalate exceed the renal excretion capacity, leading to systemic deposits in various organs from increased oxalate in the blood. We report a case of a young male with end-stage renal disease (ESRD), recurrent nephrolithiasis, medullary sponge kidney, and transfusion-dependent anemia. Peripheral smear revealed dacrocytes, and bone marrow biopsy showed oxalate crystals consistent with primary oxalosis contributing to his transfusiondependent anemia with suboptimal response to erythropoietin stimulating agents. Molecular testing confirmed primary hyperoxaluria type 1 (PH1) due to AGXT mutations. He was treated with hydration, high-dose pyridoxine, and monitored for nephrolithiasis. This case highlights the importance of considering primary hyperoxaluria in patients with impaired renal function and non-diagnostic anemia work up. Keywords: Hyperoxaluria; Primary hyperoxalosis; Anemia; Myelophthisic anemia; Oxalate crystals; Oxalate biosynthesis