[Tubulo-interstitial nephritis in inflammatory bowel disease: extra-intestinal manifestation or drug toxicity?]. / Tubulo-interstitiële nefritis bij inflammatoire darmziekte: extra-intestinale manifestatie of geneesmiddeltoxiciteit?

Chronic inflammatory bowel disease (IBD) is seldom complicated by renal function disorder, but when this occurs the consequences are serious. In addition to the known effects of 5-aminosalicylates, there is also evidence that tubulo-interstitial nephritis (TIN) occurs as an extra-intestinal manifestation of IBD. A 27-year-old woman with colitis ulcerosa, developed end-stage renal insufficiency due to a mesalazine-induced TIN. She was treated by haemodialysis for two years before she underwent renal transplantation. Another patient, a 36-year-old man with Crohn's disease, developed extensive granulomatous nephritis with stable moderate renal function. After excluding other possible causes, we diagnosed an extra-intestinal manifestation of his Crohn's disease. There are no official guidelines on renal function monitoring in IBD patients, nor is there consensus in literature. We advise renal monitoring after three months of treatment with 5-aminosalicylates, followed by monitoring every year. Patients not receiving treatment should be monitored every year.

Hb zoeterwoude [beta23(B5)Val-->Ala)]: a new beta-globin variant found in association with erythrocytosis.

We describe the characterization of a new hemoglobin (Hb) variant found in a 77-year-old Dutch woman, suspected of hypoxia-mediated erythrocytosis. The typical blood parameters (Hb 17.3 g/dL; PCV 0.525 L/L; RBC 5.82 x 10(12)/L) could not be explained by any of the pathological or physiological conditions causing erythrocytosis. The patient was preventively phlebotomized because of intermittent claudication and erythrocytosis. At the hematological and biochemical levels, no anemia or hemolysis were present and no abnormal Hb fractions were detectable on alkaline electrophoresis or high performance liquid chromatography (HPLC). Molecular analysis revealed intact alpha-globin genes and a heterozygosity for a GTT-->GCT transition at codon 23 of the beta-globin gene, causing a Val-->Ala amino acid substitution. The P50 measured in full blood indicated that this mutant has an elevated oxygen affinity. This is the fourth single nucleotide substitution at codon 23 of the beta gene and the second associated with erythrocytosis. Because the family was not available for investigation no information was obtained as to whether the mutation represents a de novo event or was inherited, and might be a more common cause of erythrocytosis in Dutch patients. Considering the relatively high frequency of beta-thalassemia (thal) in the large allochthonous population in The Netherlands, combinations of Hb Zoeterwoude and beta-thal traits may lead to hemizygosity, with severe hypoxia and erythrocytosis from a few months after birth.