title: Distal renal tubular acidosis with multiorgan autoimmunity: a case report.
abstract: A 61-year-old woman with a history of pernicious anemia presented with progressive muscle weakness and dysarthria. Hypokalemic paralysis (serum potassium, 1.4 mEq/L) due to distal renal tubular acidosis (dRTA) was diagnosed. After excluding several possible causes, dRTA was considered autoimmune. However, the patient did not meet criteria for any of the autoimmune disorders classically associated with dRTA. She had very high antibody titers against parietal cells, intrinsic factor, and thyroid peroxidase (despite normal thyroid function). The patient consented to a kidney biopsy, and acid-base transporters, anion exchanger type 1 (AE1), and pendrin were undetectable by immunofluorescence. Indirect immunofluorescence detected diminished abundance of AE1- and pendrin-expressing intercalated cells in the kidney, as well as staining by the patient's serum of normal human intercalated cells and parietal cells expressing the adenosine triphosphatase hydrogen/potassium pump (H(+)/K(+)-ATPase) in normal human gastric mucosa. The dRTA likely is caused by circulating autoantibodies against intercalated cells, with possible cross-reactivity against structures containing gastric H(+)/K(+)-ATPase. This case demonstrates that in patients with dRTA without a classic autoimmune disorder, autoimmunity may still be the underlying cause. The mechanisms involved in autoantibody development and how dRTA can be caused by highly specific autoantibodies against intercalated cells have yet to be determined.
authors.affiliation: Department of Internal Medicine, ZGT Hospital, Almelo, the Netherlands. Electronic address: marijkevandenwildenberg@hotmail.com.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: van den Wildenberg
authors.affiliation: Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Ewout J
authors.initials: EJ
authors.lastname: Hoorn
authors.affiliation: Division of Nephrology, University Hospital Zurich, Zürich, Switzerland; Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Nilufar
authors.initials: N
authors.lastname: Mohebbi
authors.affiliation: Institute of Physiology and Zürich Center for Human Intergrative Physiology, University of Zürich, Zürich, Switzerland.
authors.forename: Carsten A
authors.initials: CA
authors.lastname: Wagner
authors.affiliation: Department of Internal Medicine, ZGT Hospital, Almelo, the Netherlands.
authors.forename: Arend-Jan
authors.initials: AJ
authors.lastname: Woittiez
authors.affiliation: Department of Internal Medicine, ZGT Hospital, Almelo, the Netherlands.
authors.forename: Peter A M
authors.initials: PA
authors.lastname: de Vries
authors.affiliation: Department of Internal Medicine, ZGT Hospital, Almelo, the Netherlands.
authors.forename: Gozewijn D
authors.initials: GD
authors.lastname: Laverman
mesh_terms: D000141:Acidosis, Renal Tubular / Q000175:diagnosis* / Q000276:immunology*; D000906:Antibodies / Q000097:blood; D015551:Autoimmunity; D005260:Female; D006801:Humans; D007668:Kidney / Q000276:immunology; D008875:Middle Aged; D013270:Stomach / Q000276:immunology; D013961:Thyroid Gland / Q000276:immunology
chemical_list: D000906:Antibodies
keywords: Distal renal tubular acidosis (dRTA); anion exchanger type 1 (AE1); antibodies; autoimmunity; hypokalemia; immunofluorescence; intercalated cells; kidney biopsy; stomach; type I RTA