title: Lack of correlation between calcium intake and serum calcium levels in stable haemodialysis subjects.
abstract: BACKGROUND
  The relationship between calcium intake and serum calcium level in hemodialysis patients is poorly understood.
  
  
  METHODS
  We quantify total oral calcium intake using detailed 7-day food diaries with 294 patient days of observation in 42 stable, non-diabetic hemodialysis subjects.
  
  
  RESULTS
  Mean (SD) albumin-corrected serum calcium was 9.84 mg/dl (0.8). The albumin-corrected serum calcium was low (<8.4 mg/dl) in 2 patients, low-normal (8.4-9.49) in 9 patients, high-normal (9.5-10.2) in 18 patients and high (>10.2) in 13 patients. Mean (SD) total (diet plus binder) oral calcium intake was 1996 mg/day (1,020); 16 patients (38%) had a total calcium intake >2,000 mg/day. Calcium intake and serum calcium were poorly correlated (Spearman rank method), r = 0.14, p = 0.39. Median calcium intakes were similar in those with normal (1,990 mg/day), high-normal (1,926 mg/day) and high calcium groups (1,713 mg/day), p = 0.73 (Kruskal-Wallis), p = 0.29 (linear test for trend). Forty-one percent (11/27) of patients who had serum calcium in the normal range had a calcium intake greater than 2 g/day, while 11.5% had a calcium intake greater than 3 g/day. In subjects with a parathyroid hormone (PTH) concentration <300 pg/ml (n = 20), the correlation between calcium intake and either uncorrected serum calcium or albumin-corrected serum calcium was stronger, r = 0.45, p = 0.05 and r = 0.38, p = 0.10, respectively, though there remained wide variability in calcium intake.
  
  
  CONCLUSIONS
  Serum calcium is not a reliable indicator of calcium intake, especially at PTH > or = 300 pg/ml. An excessive calcium intake may coexist with a normal serum calcium level.
authors: Department of Nutrition and Dietetics, Cork University Hospital, Cork, Ireland.
authors: Fiona N
authors: FN
authors: Byrne
authors: Sinead
authors: S
authors: Kinsella
authors: Dermot J
authors: DJ
authors: Murnaghan
authors: Mairead
authors: M
authors: Kiely
authors: Joseph A
authors: JA
authors: Eustace
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002118:Calcium / Q000097:blood*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D006435:Renal Dialysis; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D002136:Calcium, Dietary; D010281:Parathyroid Hormone; D002118:Calcium