Discussion P W6 Reply to peer 1

GFR is a key indicator of kidney function, reflecting how well the kidneys filter blood. The most accurate method of measuring GFR involves using exogenous markers such as inulin clearance, which is freely filtered by the glomerulus and neither reabsorbed nor secreted by renal tubules (Levey et al., 2020). However, inulin clearance is time-consuming and not practical for routine clinical use. Instead, creatinine clearance is commonly used, though it has limitations since creatinine undergoes some tubular secretion, leading to an overestimation of GFR. Serum creatinine-based equations, such as the CKD-EPI or MDRD formulas, provide a more practical estimation, adjusting for variables like age, sex, and body surface area (Inker et al., 2021). Another alternative is cystatin C, a protein filtered by the glomerulus, offering a more reliable marker in certain populations, such as children and those with fluctuating muscle mass (Sharma et al., 2022).

     Vesicoureteral reflux is a congenital or acquired condition where urine flows retrograde from the bladder into the ureters due to an incompetent vesicoureteral junction. Normally, the ureter enters the bladder at an oblique angle, forming a functional one-way valve that prevents backflow. In VUR, this angle is disrupted due to congenital abnormalities in the ureter’s insertion or bladder wall, resulting in urine reflux during bladder contraction (Shapiro et al., 2021). VUR increases the risk of urinary tract infections and renal scarring due to recurrent pyelonephritis (infection gets so bad it migrates to the kidney, resulting in kidney infection, which is a more serious infection). Higher-grade VUR can lead to progressive kidney damage and hypertension if untreated. Management varies based on severity, ranging from antibiotic prophylaxis to surgical intervention for persistent or high-grade cases.

References

Inker, L. A., Schmid, C. H., Tighiouart, H., et al. (2021). Estimating glomerular filtration rate using serum creatinine and cystatin C. The New England Journal of Medicine, 385(19), 1737-1749.

Levey, A. S., Stevens, L. A., Schmid, C. H., et al. (2020). A new equation to estimate glomerular filtration rate. Annals of Internal Medicine, 150(9), 604-612.

Sharma, A., Menon, S., Ghosh, A., et al. (2022). Cystatin C-based estimation of glomerular filtration rate in children: A systematic review. Pediatric Nephrology, 37(4), 829-840.

Shapiro, E., Tejwani, R., & Franco, I. (2021). Vesicoureteral reflux in children: Pathophysiology, diagnosis, and management. The Journal of Urology, 206(2), 265-274.