Comparison of urinary proteins in calcium stone formers and healthy individuals: a case-control study.
OBJECTIVE
This study aimed at comparing the urinary protein levels in calcium stone formers with those of healthy individuals.


METHODS
From January 2002 until June 2004, 100 calcium stone formers (mean age 38.6 +/- 10.3 years), who had at least two episodes of calcium stone formation, were compared with 100 healthy individuals (mean age 33.8 +/- 9.7 years). Their 24-hour urinary protein levels, using SDS-PAGE, were measured.


RESULTS
The mean 24-hour urinary Tamm-Horsfall protein (THP) levels were 3.3 +/- 0.8 mg in the case group and 4.6 +/- 1.9 mg in the controls, and the difference was not statistically significant (p = 0.53). However, the THP levels in individuals with and without bacteriuria were significantly different (15.8 +/- 3.3 mg vs. 2.6 +/- 1.0 mg, p = 0.0001). The mean 24-hour urinary albumin concentrations were 163.31 +/- 15.1 mg in the case group and 74.26 +/- 4.6 mg in the controls. The mean 24-hour urinary transferrin levels were 8.09 +/- 2.7 mg in the case group and 0.40 +/- 0.3 mg in the controls. The differences were statistically significant for both albumin and transferrin (p < 0.0001 and p = 0.0063, respectively). There were no significant differences in any other mean urinary protein concentrations between cases and controls.


CONCLUSIONS
The THP level in the urine of stone formers is not quantitatively different from that of healthy individuals, but it increases in association with bacteriuria. Albumin and transferrin may play a presumptive role in stone formation.
Pourmand
Gholamreza
G
Urology Research Center, Tehran University of Medical Sciences, Tehran, Iran. gh_pourmand@hotmail.com
Nasseh
Hamidreza
H
Sarrafnejad
Abdolfattah
A
Mojtahedi
Alireza
A
Mehrsai
Abdolrasoul
A
Alamdari
Darioush Hamidi
DH
Nourijelyani
Keramat
K
D000328:Adult; D002129:Calcium Oxalate / Q000032:analysis*; D002130:Calcium Phosphates / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011507:Proteinuria / Q000652:urine*; D014545:Urinary Calculi / Q000737:chemistry* / Q000652:urine*
D002130:Calcium Phosphates; D002129:Calcium Oxalate; C020243:calcium phosphate