title: Circadian rhythm of serum phosphate, calcium and parathyroid hormone levels in hemodialysis patients.
abstract: BACKGROUND
  Serum levels of Phosphate (P), Calcium (Ca) and Parathyroid hormone (PTH) show circadian rhythms in healthy people. The aim of this study is to investigate whether there is also a rhythm in Hemodialysis (HD) patients.
  
  
  METHODS
  We studied 15 (11 M, 4 F) HD patients, ages were 26 - 70 (mean 53 +/- 15) years. Two of the patients had history of parathyroidectomy operation. Serum levels of phosphate, calcium, albumin and PTH were evaluated six times at 07.00, 11.00, 15.00, 19.00, 23.00 and 03.00 on the second day after scheduled HD session.
  
  
  RESULTS
  The lowest serum phosphate levels were found at 15.00 (5.41 +/- 1.76 mg/dL), the highest levels were 5.97 +/- 1.77 mg/dL at 03.00. The lowest serum Ca levels were 7.90 +/- 1.31 mg/dL at 03.00, the highest levels were 8.39 +/- 1.20 mg/dL at 15.00. Serum levels of PTH increased two times in a day and then decreased. The lowest levels were 330.07 +/- 203.57 pg/mL at 07.00, the highest levels were 418.30 +/- 206.24 pg/mL at 15.00. The results of two patients who had parathyroidectomy history disclosed that the lowest levels of phosphate were 2.87 +/- 0.12 mg/dL at 15.00, the highest levels were 4.37 +/- 1.25 mg/dL at 07.00. Serum Ca levels were as; the lowest levels: 8.29 +/- 3.5 mg/dL at 03.00, the highest levels 9.30 +/- 3.50 mg/dL at 19.00. As expected, serum PTH levels were constantly low during the day disclosing no correlation with other parameters.
  
  
  CONCLUSIONS
  These results show that serum P, Ca and PTH levels exhibit a circadian rhythm also in HD patients. The rhythm predominantly depends on endogen factors and intravascular volume.
authors.affiliation: Department of Nephrology, Baskent University School of Medicine, Adana, Turkey.
authors.forename: H
authors.initials: H
authors.lastname: Micozkadioglu
authors.forename: R
authors.initials: R
authors.lastname: Ozelsancak
authors.forename: I
authors.initials: I
authors.lastname: Yildiz
authors.forename: E
authors.initials: E
authors.lastname: Erken
authors.forename: A
authors.initials: A
authors.lastname: Zumrutdal
authors.forename: D
authors.initials: D
authors.lastname: Torun
authors.forename: M
authors.initials: M
authors.lastname: Haberal
mesh_terms: D000328:Adult; D000368:Aged; D002118:Calcium / Q000097:blood*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010710:Phosphates / Q000097:blood*; D006435:Renal Dialysis
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D002118:Calcium