Oxalosis in the Bone and Bone Marrow

Introduction Hyperoxaluria is characterized by supersaturation of calcium oxalate in the urine, and is strongly associated with nephrolithiasis and nephrocalcinosis. Oxalate is the salt form of oxalic acid and is a natural end product of glyoxylate metabolism. Oxalate does not appear to be needed for any human body process and normally more than 90% is excreted by the kidneys, with a small amount of excretion into the lower gut. Hyperoxaluria can result form excessive dietary intake of oxalates, overproduction of oxalates from the intestinal tract associated with intestinal diseases (enteric hyperoxaluria) and abnormalities in oxalate metabolism (primary hyperoxaluria)1. Long-standing and unattended hyperoxaluria can progressively impair renal functions, and ultimately lead to renal failure. This devastating phenomenon is characterized by oxalosis, a condition in which calcium oxalate crystals are deposited in the extrarenal organs. The common sites of oxalate deposition are the bones, bone marrow, blood vessels, central nervous system, peripheral nerves, retina, skin, and thyroid, etc2. Renal stones are a fairly common clinical entity. Many patients having renal stones present with renal colic and/or haematuria; however, an incidental diagnosis of nephrolithiasis on routine radiological examination is not uncommon. Since majority of cases of nephrolithiasis are not associated with metabolic oxalate defects, a metabolic screening for oxalate metabolism is usually not warranted in patients with their first renal stone. However, patients with recurrent renal stones and those presenting with renal calcinosis should be looked at with a strong clinical suspicion of underlying metabolic abnormalities1. Renal failure, which ensues with the passage of time in almost all the patients of oxalosis, is generally associated with anaemia. Deposition of oxalates in the bone marrow further aggravates anaemia and other cytopenias, and may cause leucoerythroblastic blood picture3. Here we report the case of a young adult having systemic oxalosis probably associated with late onset primary hyperoxaluria (PH). The patient presented with bilateral nephrolithiasis, obstructed uropathy, end stage renal disease and bicytopenia (anemia and thrombocytopenia). The histological diagnosis of oxalosis was made on bone marrow trephine biopsy.