Akira Iguchi

Administration of Ferric Citrate Hydrate Decreases Circulating FGF23 Levels Independently of Serum Phosphate Levels in Hemodialysis Patients with Iron Deficiency.

Background/Aim: Dietary phosphate intake and vitamin D receptor activator (VDRA) regulate fibroblast growth factor 23 (FGF23); iron may modulate FGF23 metabolism. We aimed to determine whether oral iron supplementation influences serum FGF23 concentration in hemodialysis (HD) patients, while excluding the effect of dietary phosphate intake. Methods: This prospective study enrolled 27 maintenance HD patients with iron deficiency and hyperphosphatemia treated with sevelamer-HCl. The phosphate binder was changed from sevelamer-HCl to ferric citrate hydrate (FCH) to maintain constant phosphate levels. VDRA, other phosphate binders, and cinacalcet HCl were not changed. Serum intact FGF23, C-terminal FGF23 (C-term FGF23), intact parathyroid hormone (PTH), 1,25(OH)2D and other parameters were monitored for 12 weeks. Results: Serum phosphate levels (5.89 ± 1.45 mg/dl at baseline, 5.54 ± 1.35 mg/dl at 12 weeks) and 1,25(OH)2D levels were unchanged. Serum ferritin levels increased from 25.6 ± 24.3 ng/ml at baseline to 55.8 ± 33.5 ng/ml at 12 weeks with FCH administration. Serum intact FGF23 and C-term FGF23 levels significantly decreased at 12 weeks compared with baseline (2,000 (1,300.0-3,471.4) to 1,771.4 (1,142.9-2,342.9) pg/ml, p = 0.01, and 1,608.7 (634.8-2,308.7) to 1,165.2 (626.1-1,547.8) RU/ml, p = 0.007, respectively); serum intact PTH levels significantly increased (96 (65-125) to 173 (114-283) pg/ml, p < 0.001). Conclusions: Oral FCH administration decreased serum intact FGF23 and C-term FGF23 levels and increased intact PTH levels; phosphate and 1,25(OH)2D levels were unchanged. Oral FCH administration to treat iron deficiency is a possible strategy for reducing serum FGF23 levels independent of phosphate and VDRA.

A case of MPO- and PR3-ANCA-positive hypertrophic cranial pachymeningitis with elevated serum IgG4

We report a case of orbital tumor and hypertrophic cranial pachymeningitis in a 64-year-old woman, who was initially suspected to have IgG4-related disease because of an elevated level of serum IgG4 at onset. However, her condition was resistant to glucocorticoid therapy, and additional cyclophosphamide was necessary to control the disease activity. Additional features included elevated levels of serum myeloperoxidase (MPO) and proteinase-3-anti-neutrophil cytoplasmic antibody (PR3-ANCA), and biopsy specimens from the orbital mass revealed very few infiltrating IgG4-positive cells. Instead, rupture of the elastic layer of the arterial walls with neovascularization and a small number of giant cells were observed. Considering these findings and the clinical course, the disease was considered more likely to be ANCA-associated pachymeningitis with elevation of the serum IgG4 level.

Serum magnesium concentration is inversely associated with fibroblast growth factor 23 in haemodialysis patients

Fibroblast growth factor 23 is reported to be a pivotal regulator for the chronic kidney disease‐mineral bone disorders, working in coordinated ways with phosphate, calcium, and parathyroid hormone. However, whether there is a relationship between fibroblast growth factor 23 and magnesium is currently unclear. To address this, we performed a cross‐sectional observational study in haemodialysis patients.

Three Cases of Gastric Antral Vascular Ectasia in Chronic Renal Failure

Gastric antral vascular ectasia (GAVE) is currently recognized as an important cause of gastrointestinal bleeding. Chronic kidney disease (CKD) is associated with a high incidence of GAVE. We report 3 patients with CKD who presented with severe anemia and were diagnosed with GAVE; they were resistant to endoscopic argon plasma coagulation. However, remission of anemia and improvement in GAVE lesions were observed after the initiation of hemodialysis. The pathogenesis of GAVE remains largely unknown, but mechanical stress of the antrum could play an important role. This stress may be reduced by hemodialysis through improvement of uremia-associated gastrointestinal symptoms. Therefore, the initiation of hemodialysis might be effective for intractable GAVE in CKD patients.

Adsorption of Protein-Bound Uremic Toxins Through Direct Hemoperfusion With Hexadecyl-Immobilized Cellulose Beads in Patients Undergoing Hemodialysis

An accumulation of protein-bound uremic toxins (PBUTs) is one of major reasons for development of uremia-related complications. We examined the PBUT removal ability of a hexadecyl-immobilized cellulose bead (HICB)-containing column for patients undergoing hemodialysis. Adsorption of indoxyl sulfate (IS), a representative PBUT, to HICBs was examined in vitro. The HICB column was used in patients undergoing hemodialysis for direct hemoperfusion with a regular hemodialyzer. The serum IS, indole acetic acid (IAA), phenyl sulfate (PhS), and p-cresyl sulfate (PCS) levels were measured before and after passing the column. HICBs adsorbed protein-free (free) IS in a dose- and time-dependent manner in vitro (55.4 ± 1.4% adsorption of 1 millimolar, 251 µg/mL, IS for 1 h). In clinical studies, passing the HICB-containing column decreased the serum level of free IS, IAA, PhS, and PCS levels significantly (by 34.4 ± 30.0%, 34.8 ± 25.4%, 28.4 ± 18.0%, and 34.9 ± 22.1%, respectively), but not protein-bound toxins in maintenance hemodialysis patients. HICBs absorbed some amount of free PBUTs, but the clinical trial to use HICB column did not show effect to reduce serum PBUTs level in hemodialysis patients. Adsorption treatment by means of direct hemoperfusion with regular hemodialysis may become an attractive blood purification treatment to increase PBUT removal when more effective materials to adsorb PBUTs selectively will be developed.

A case of podocytic infolding glomerulopathy with focal segmental glomerulosclerosis.

Podocytic infolding glomerulopathy (PIG) has been proposed as a new disease entity. A 14-year-old girl underwent renal biopsy at our institution because of a chance finding of proteinuria. Light microscopic findings revealed a minor glomerular abnormality, but under a higher magnification, after periodic acid methenamine silver staining, a bubbling appearance in the glomerular basement membrane (GBM) was observed. An electron microscopic examination revealed microspheres in the GBM, which were sparse but global. The patient was diagnosed as having PIG. After 3 years, her urinary protein had increased and a second biopsy was performed, showing focal segmental glomerulosclerosis in addition to a lesser degree of podocytic infolding than at the first biopsy. This is the first report of a case complicated by a different type of glomerulonephritis after being diagnosed as PIG. A few cases of PIG are complicated by focal segmental glomerulosclerosis, suggesting several mechanisms for the disorder.

A case of xanthinuria type I with a novel mutation in xanthine dehydrogenase

Hereditary hypouricemia is generally caused by renal hypouricemia, an autosomal recessive disorder that is characterized by impaired renal tubular uric acid transport, or by xanthinuria, a rare autosomal recessive disorder caused by a deficiency of xanthine dehydrogenase (XDH; xanthinuria type I) or by a deficiency of both XDH and aldehyde oxidase (xanthinuria type II). In contrast to renal hypouricemia, which sometimes leads to exercise-induced acute kidney injury (EIAKI), xanthinuria has not been associated with this disorder. We report here a case of xanthinuria type I due to a compound heterozygous mutation. A 46-year-old woman was found to have undetectable plasma and urinary levels of uric acid. She had no symptoms and no history of EIAKI. Xanthinuria type I was diagnosed following the allopurinol loading test. Mutation analysis revealed a compound heterozygous mutation [c.305A>G (p.Gln102Arg) and c.2567delC (p.Thr856Lysfs*73)] in the XDH gene. Of these two mutations, the former is novel. The patient did not exhibit EIAKI. However, because xanthinuria is a rare disease, the identification of additional cases is necessary to determine whether this disease is complicated with EIAKI.

IgG4-Related Kidney Disease with Retroperitoneal Fibrosis in a Patient with Diabetes Mellitus

A 74-year-old man with type 2 diabetes mellitus, in whom persistent proteinuria and renal dysfunction had been noted for several years, developed a rapid increase in his serum creatinine concentration and was referred to our hospital because of concern about a potential exacerbation of diabetic nephropathy. Laboratory findings revealed high levels of serum IgG and IgG4. Computed tomography examination showed right hydronephrosis with retroperitoneal fibrosis. Although the hydronephrosis resolved with ureteral stent placement, the serum creatinine level further increased and renal biopsy was performed. Renal histology revealed tubulointerstitial nephritis with an abundant IgG4-positive plasma cell infiltrate and marked fibrosis, compatible with IgG4-related kidney disease (IgG4-RKD). The patient was treated with glucocorticoids and his serum creatinine level decreased to 1.5 mg/dL. This experience suggests that IgG4-RKD should be considered in cases of chronic kidney disease in which the renal dysfunction progresses rapidly without apparent cause, and that IgG4-RKD may be accompanied by retroperitoneal fibrosis in IgG4-related disease.

A case of antiglomerular basement membrane glomerulonephritis complicated by membranous nephropathy

Abstract The sequential or simultaneous presentation of anti-glomerular basement membrane (anti-GBM) glomerulonephritis with membranous nephropathy (MN) has been infrequently reported. Although the mechanism underlying MN superimposed on anti-GBM glomerulonephritis is unknown, the two entities are believed to be interrelated. We report the case of a 75-year-old woman diagnosed with rapidly progressive glomerulonephritis. Renal biopsy revealed crescentic glomerulonephritis with linear and granular staining of immunofluorescent IgG1 and IgG4 granular staining on the capillary loops. Electron microscopy revealed extensive subepithelial deposits. These findings suggested simultaneous development of anti-GBM glomerulonephritis and MN in this case. Serum phospholipase A2 receptor (PLA2R) antibody was negative. The patient was treated with prednisolone and plasma exchange, resulting in resolution of renal insufficiency and a decrease in urinary protein. The rapid decrease in urinary protein and absence of PLA2R antibody suggest that the mechanism of MN associated with anti-GBM glomerulonephritis differs from that of primary MN.