title: Calcium ions are abnormally distributed in the skin of haemodialysis patients with uraemic pruritus.
abstract: BACKGROUND
  Although a close relationship between uraemic pruritus and serum calcium levels has been demonstrated for some time, the degree of pruritus was not always correlated with calcium concentrations. In the present study, we assessed calcium ion distribution in the skin of chronic haemodialysis patients with and without pruritus.
  
  
  METHODS
  We excluded patients with concomitant psoriasis or atopic dermatitis or with a previous history of allergy, those who had an arteriovenous fistula created prior to induction of haemodialysis, and patients with only mild pruritus. From the enrolled 22 haemodialysis patients, we obtained forearm skin samples during arteriovenous fistula surgery. These patients were divided into two groups based their grade of pruritus. The pruritus group included patients with moderate to severe grades of pruritus (n = 11, age 64 +/-13 years) and the non-pruritus group consisted of patients without pruritus (n = 11, age 59 +/-13 years). We compared the distribution of calcium ions in the epidermis between the two groups using the ion-capture method (oxalate-pyroantimonate-osmium technique). In addition, we examined and compared the groups for thicknesses of the basal, spinous and granular layers, as well as of the stratum corneum using an electron microscope.
  
  
  RESULTS
  The pruritus group had significantly higher calcium ion deposition in the extracellular fluid and cytoplasm of basal cells, and in the extracellular fluid, nuclei and cytoplasm of spinous cells compared with the non-pruritus group. In contrast, calcium ion depositions were similar between the two groups in the dermis/basal layer interface, the nucleus of basal cells, the nucleus and cytoplasm of granular cells, exterior of granular cells, the granular cells/stratum corneum interface, and in the interior and exterior of corneocytes. Although the stratum corneum was significantly thicker in the pruritus group than in the non-pruritus group, there were no differences in basal cell, spinal cell or granular cell layer thicknesses.
  
  
  CONCLUSIONS
  In chronic haemodialysis patients with pruritus, the calcium ion concentration in the deepest layer of the epidermis was increased, which indicated a disrupted calcium ion gradient in the skin. These findings point to a role for increased skin calcium ion concentrations in the development and/or maintenance of uraemic pruritus. However, more extensive studies in larger patient cohorts will be necessary to confirm this hypothesis.
authors.affiliation: Department of Urology, Oyokyo Kidney Research Institute, Hirosaki Hospital, 90 Yamazaki, Kozawa, Hirosaki 036-8243, Japan. momose-a@oyokyo.jp
authors.forename: Akishi
authors.initials: A
authors.lastname: Momose
authors.forename: Shigemasa
authors.initials: S
authors.lastname: Kudo
authors.forename: Motoaki
authors.initials: M
authors.lastname: Sato
authors.forename: Hisao
authors.initials: H
authors.lastname: Saito
authors.forename: Katunori
authors.initials: K
authors.lastname: Nagai
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Katabira
authors.forename: Tomihisa
authors.initials: T
authors.lastname: Funyu
mesh_terms: D000368:Aged; D002118:Calcium / Q000378:metabolism*; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011537:Pruritus / Q000209:etiology / Q000378:metabolism*; D006435:Renal Dialysis; D012867:Skin / Q000378:metabolism*; D014511:Uremia / Q000150:complications / Q000378:metabolism*
chemical_list: D002118:Calcium