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Introduction: In small bowel disease such as M. Crohn, the intestinal absorption of oxalate is increased. Severe calcium oxalate deposition in multiple organs as consequence of enteric hyperoxaluria may lead to severe organ dysfunction and chronic renal failure. The management of hemodialyzed patients with short bowel syndrome may be associated with vascular access problems and oxalate infiltration of the bone marrow leading to pancytopenia. Although the risk of recurrence of the disease is very high after renal transplantation, it may be the ultimate therapeutic alternative in secondary hyperoxaluria., Case: Here, we report a patient with enteric oxalosis due to Crohn's disease. He developed end-stage renal disease, erythropoietin-resistant anemia, oxalate infiltration of the bone marrow and severe vascular access problems. Following high-urgency kidney transplantation, daily hemodiafiltration of 3 hours was performed for 2 weeks to increase oxalate clearance. Despite tubular and interstitial deposition of oxalate in the renal transplant, the patient did not require further hemodialysis and the hematocrit levels normalized., Discussion: Early treatment of hyperoxaluria due to short bowel syndrome is essential to prevent renal impairment. Declining renal function leads to a further increase in oxalate accumulation and consecutive oxalate deposition in the bone marrow or in the vascular wall. If alternative treatments such as special diet or daily hemodialysis are insufficient, kidney transplantation may be a therapeutic alternative in severe cases of enteric oxalosis despite a possible recurrence of the disease.

The transcription factor HIF-1alpha has been identified as a key regulator in the cellular and systemic response to hypoxia. Because hypoxia is frequently associated with acidosis, like in ischemia or tumour growth, we studied the impact of acidosis on the expression of the HIF-1alpha and HIF-2alpha proteins and that of the three HIF target genes carbonic anhydrase-9 (CA-9), glucose transporter-1 (Glut-1) and erythropoietin (EPO). Since the HIF-prolyl hydroxylases (PHD) modulate cellular HIF-alpha protein levels we also investigated changes in PHD mRNA expression under hypoxia and acidosis. HIF-1alpha immunoblots revealed, depending on the cell line investigated, a moderate induction of HIF-alpha protein levels by acidosis in normoxia (Hep3B cells) or hypoxia (HeLa cells). Concordantly, the activity of HIF-driven luciferase reporters was slightly enhanced at pH 7.0. In contrast, HIF target genes exhibited divergent responses to acidosis: basal and hypoxia-induced CA-9 mRNA levels were further increased, whereas hypoxic EPO mRNA induction was attenuated, and Glut-1 mRNA levels were not altered by acidosis. Except from a small increase of hypoxia-induced PHD3 mRNA levels in HeLa cells, there was also no significant effect of acidosis on PHD expression. In conclusion, albeit HIF protein levels slightly induced by acidosis and the inconsistent regulation of HIF target genes under acidosis suggest additional, yet unidentified pH-sensitive factors to be involved in the regulation of these genes.