Investigation of the effect of excessively high dose creatinine clearance on proteinuria-induced kidney ratios to A real rate of glomerular filtration and long-term renal function

İntroduction: Proteinuria is a primary cause of underlying disease, as well as a major cause of damage to nephrons. In addition, hyperfiltration (CCr 150 ml / min / 1.73 m2) contributes to glomerular hypertension by increasing intraglomerular osmotic pressure. Many methods have been developed for the detection of hyperfiltration and it is the most commonly used creatinine clearance in the clinic. However, it is recommended to use different endogenous and exogenous markers in the determination of glomerular filtration rate (GFR) as creatinine clerance (CCr) may affect many factors. Aim: It has been aimed to show that the excessively high CCr values in patients with proteinuria are a result of decreased serum creatinine levels due to increased tubular secretion and low glomerular oncotic pressure caused by decreased serum albumin levels. In addition, serum cystatin C levels, which is a more reliable marker than creatinine, were used to show whether excessive levels reflect the truth. Methods: The study group consisted of 71 patients aged 3-18 years who were followed up by Dokuz Eylül University Department of Child Nephrology for proteinuria and control group consisting of 10 people. At admission, 3., 6., 12. months and annually mean values of serum creatinine, serum albumin, proteinuria levels and CCr were recorded. eGFRcysC was calculated by looking at serum cystatin C level in all patients at the time of study. Results: The study group was divided into three groups, with remission (group 1) 52 (73.2%), with attack (group 2) 8 (11.2%), with isolated proteinuria (group 3) 11 (15.4%) patients 10 control group patients. The mean serum creatinine levels of patients in Group 2 were 0.3±0.3 mg / dL, low serum albumin levels' average was 2.3 ± 0.7g/dL, high proteinuria levels were found to be mean 173±119 mg /m2/h and high CCr' ranged from 262 ± 128 ml /min /1.73 m2 to other groups. However, no significant difference was observed between serum cystatin C and eGFRcysC. Likewise, CCr and proteinuria levels were higher, serum creatinine and serum albumin levels were lower in patients with hyperfiltration at the time of test, whereas cystatin C and eGFRcysC were not significantly different (p <0.05). Conclusion: Proteinuria is both a cause and a result of hyperfiltration. To demonstrate hyperfiltration, CCr, the most commonly used in practice, is affected by many factors. Extremely high CCr is a result of decreased glomerular oncotic pressure caused by low serum albumin levels. In these patients, it is recommended to measure the serum cystatin C level that gives the closest results to the actual GFR rather than the creatinine-based eGFR measurement. Keywords: Proteinuria, hyperfiltration, serum cystatin C