Determination of Clara cell protein urinary elimination as a marker of tubular dysfunction

• Published in: Pediatric nephrology (Berlin, West) Vol. 24; no. 4; pp. 747 - 752
• Main Authors: Martín-Granado, Ascensión, Vázquez-Moncholí, Carmen, Luis-Yanes, María Isabel, López-Méndez, Marisela, García-Nieto, Víctor
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2009; Springer; Springer Nature B.V
• Subjects: Acetylglucosaminidase - urine; Adolescent; beta 2-Microglobulin - urine; Biomarkers - urine; Child; Child, Preschool; Creatinine; Creatinine - urine; Cyclosporine - therapeutic use; Female; Hospitals; Humans; Immunosuppressive Agents - therapeutic use; Infant; Kidney Diseases - drug therapy; Kidney Diseases - pathology; Kidney Diseases - urine; Kidney Failure, Chronic - drug therapy; Kidney Failure, Chronic - pathology; Kidney Failure, Chronic - urine; Kidney Tubules, Proximal - metabolism; Kidney Tubules, Proximal - pathology; Kidney Tubules, Proximal - physiopathology; Male; Medicine & Public Health; Nephrology; Original Article; Patients; Pediatrics; Proteins; Urinary tract diseases; Urinary tract infections; Urine; Urogenital system; Urology; Uteroglobin - urine; Young Adult; Canary Islands; Spain; Tenerife; Clara cell protein; Cyclosporine A; Chronic renal failure; Hypercalciuria; Tubular proximal dysfunction; Hypocitraturia
• ISSN: 0931-041X; 1432-198X
• DOI: 10.1007/s00467-008-1078-5

Clara cell 16-kDa protein (CC16) is a protein expressed primarily by the bronchial cells. It is rapidly eliminated by glomerular filtration, reabsorbed almost entirely, and catabolized in proximal tubule cells. To date, normal values for urinary CC16 in healthy children have not been determined. We have studied 63 pediatric patients (mean age 8.17 ± 3.91 years) and 31 healthy children (control group; mean age 8.83 ± 3.65 years). In the control group, the CC16/creatinine ratio was 1.22 ± 1.52 μg/g. In 16 out of 31 control children, the value of the ratio was zero. Fourteen patients (22.2%) showed a high CC16/creatinine ratio; in contrast, among these same patients, the ratio N-acetyl-β- d -glucosaminidase (NAG)/creatinine was elevated in seven cases (11.1%) and the ratio β2-microglobulin/creatinine was elevated in seven cases (11.1%). The three parameters were in agreement in 51 patients (80.9%). Among the patients, the CC16/creatinine ratio was correlated with both the β2-microglobulin/creatinina ratio ( r  = 0.76, P  < 0.001) and the NAG/creatinine ratio ( r  = 0.6, P < 0.001). Our findings indicate that CC16 is a good marker of proximal tubular function in childhood. The highest observed values were in children with proximal tubulopathies, in children with chronic renal failure, and in those treated with cyclosporine.