Chronic kidney disease (CKD) is a serious, worldwide public health issue with a high morbidity, mortality, and expense associated with it. It is characterized by gradual and irreversible deterioration of renal function persisting for more than three months. Due to the high prevalence of diabetes mellitus, hypertension, obesity, cardiovascular diseases, and an ageing population, the prevalence of CKD has been rapidly rising and expanding all over the world. CKD may lead to end-stage renal disease (ESRD), which results in additional health care costs and impacts quality of life and could lead to dialysis or renal transplantation [1,2]. Renal function evaluation is crucial for the diagnosis, staging, and monitoring of CKD. Estimated glomerular filtration rate (eGFR) is the most accepted parameter used to assess renal function, and is typically calculated from serum creatinine levels and equations like the Modification of Diet in Renal Disease (MDRD). A decrease in eGFR is associated with worsening renal function and progression to more advanced stages of CKD. Serum creatinine, however, can be affected by age, gender, muscle mass, nutrition, and hydration, so renal function may not be accurately assessed in some patients [3,4]. Ultrasonography is an inexpensive, non-invasive, radiation-free, and widely available imaging modality that is often employed to evaluate renal diseases. It gives significant information, such as renal size, cortex echogenicity, thickness of the cortex and medulla, corticomedullary differentiation, and presence of hydronephrosis and cystic lesions. Ultrasonography is frequently used to assess renal size, which is decreased, increased cortical echogenicity, and renal cortex thinning in CKD patients, as a result of progressive nephron loss and renal fibrosis [5,6]. Recently, renal cortical thickness has been recognized as an important sonographic parameter to evaluate renal function. The renal cortex has glomeruli and proximal tubules, which are responsible for filtration and reabsorption. In CKD, progressive destruction of nephrons results in a decrease in the thickness of the cortex, and this decrease can be a measure of the degree of renal impairment. Multiple studies have shown that there is a strong positive correlation between increased renal cortical thickness and increased eGFR, so renal cortical thickness may be a useful indicator of renal function [7,8]. The cortical thickness is a more robust predictor of renal functional status than renal length and parenchymal thickness. Renal cortical thickness can be easily calculated during routine ultrasound examination without any additional discomfort to patients or cost. It could aid in identifying patients with advanced renal disease and in more effectively tracking disease progression [9]. While several studies report the usefulness of renal cortical thickness in the assessment of CKD, there are few local data that correlate renal cortical thickness with eGFR in the study population. Thus, this study was undertaken to see if there was any correlation between renal cortical thickness, measured by ultrasonography, and the estimated glomerular filtration rate in patients with chronic kidney disease. The results could pave the way for using renal cortical thickness as a readily available imaging biomarker for the evaluation and monitoring of patients with CKD [10].

Study Objective

To assess the association between renal cortical thickness (on ultrasonography) and estimated glomerular filtration rate (eGFR) in chronic kidney disease (CKD) patients in a tertiary care hospital

Study Design & Setting It was a cross-sectional study in the Radiology and Nephrology Department of prime teaching hospital Peshawar for six months from July to December 2025. Participants The patients were selected through a non-probability consecutive sampling technique, and a total of 100 patients aged between 18 and 75 years and diagnosed with chronic kidney disease were included. Patients who attended nephrology outpatient and inpatient departments were enrolled, both male and female. Acute kidney injury, renal malignancy, hydronephrosis, and polycystic kidney disease were excluded to reduce confounding variables. Sample Size Calculation The 100 patients were determined by using the WHO sample size calculator, with a 95% confidence level, 5% margin of error, and based on the assumption that there was a significant correlation between renal cortical thickness and estimated glomerular filtration rate among chronic kidney disease patients, as suggested by previous publications. Inclusion Criteria • Patients aged 18–75 years • These are cases that are diagnosed as chronic kidney disease. • Both male and female patients • Patients who were willing to be involved in the study Exclusion Criteria • Acute kidney injury • Tumors or malignancy of the kidneys • Hydronephrosis • Polycystic kidney disease • Congenital renal anomalies • Pregnant females Diagnostic and Management Strategy Renal ultrasonography was conducted to evaluate the bilateral renal cortical thickness and the average value recorded. The estimated glomerular filtration rate (eGFR) was estimated by the MDRD formula. Clinical and lab investigations were evaluated for diagnosis, staging, and management planning of patients with chronic kidney disease. Statistical Analysis Data were input and analyzed in SPSS version 25. The data presented for quantitative variables were mean ± standard deviation, and for qualitative variables, frequencies and percentages were used. We used the Pearson correlation test to determine the association between renal cortical thickness and eGFR. A p-value ≤0.05 was considered statistically

A total of 100 patients with chronic kidney disease were included in the study. The mean age of participants was 54.8 ± 13.2 years. Among them, 62 (62%) were males and 38 (38%) were females. The mean renal cortical thickness was 6.9 ± 1.5 mm, while the mean estimated glomerular filtration rate was 38.6 ± 15.4 mL/min/1. 73m².Patients with advanced CKD stages demonstrated significantly reduced renal cortical thickness compared with patients in earlier stages of disease. Individuals with cortical thickness less than 6 mm showed markedly lower eGFR values than patients with cortical thickness greater than 7 mm. Pearson correlation analysis demonstrated a strong positive correlation between renal cortical thickness and eGFR (r = 0.71, p < 0.001), indicating that reduction in cortical thickness was associated with worsening renal function. Renal length also showed positive association with eGFR; however, cortical thickness exhibited a comparatively stronger correlation with renal function parameters. Stratification according to age and gender showed consistent findings without statistically significant differences. These findings support the role of renal cortical thickness as a reliable non-invasive sonographic marker for assessment and monitoring of renal functional impairment in chronic kidney disease patients.

Table 1: Demographic Characteristics of Study Participants (n = 100)

Table 1 demonstrates demographic and clinical characteristics of chronic kidney disease patients included in the study.

Table 2: Mean Renal Parameters Among Study Participants

Table 2 presents mean ultrasonographic and laboratory parameters measured among patients with chronic kidney disease.

Table 3: Correlation of Renal Ultrasound Parameters with eGFR

Table 3 shows correlation between renal ultrasound parameters and estimated glomerular filtration rate among CKD patients.

Table 4: Comparison of Renal Cortical Thickness According to CKD Stages

Table 4 demonstrates progressive reduction in renal cortical thickness and eGFR with advancing stages of chronic kidney disease.

In the present study, renal cortical thickness was measured by using ultrasonography, and estimated GFR (eGFR) was measured in patients with chronic kidney disease (CKD). A significant positive correlation was found between the two parameters. eGFR levels were significantly decreased in patients with lower cortical thickness, which suggests that there was a progressive decrease in renal function as cortical thickness decreased. These results confirm the emerging evidence that renal cortical thickness is a sonographic marker that has been proven to be reliable in the assessment of renal impairment and disease progression in CKD patients [11,12].In the present study, mean renal cortical thickness was 6.9 ± 1.5 mm, and there was a strong positive correlation between renal cortical thickness and the eGFR (r = 0.71, p <0.001). The same was found by Haridas et al. (2025, who found that renal cortical thickness decreased significantly in a progressive manner with a fall in eGFR in CKD patients. They also found renal cortical thickness and renal echogenicity to be useful ultrasonographic markers for monitoring CKD progression [13]. Similarly, in another study in 2025, Iram et al. found a significant association between elevated serum creatinine and decreased cortical thickness in patients with CKD, and that renal echogenicity was associated with decreased cortical thickness. The authors highlighted that the cortical thinning was an indication of progressive nephron loss and renal fibrosis, which corroborates the findings of the present study [14,15]. The study of our study are also in agreement with the study done by Getaneh et al. in 2025, where they found that there was a clear association between sonographic renal abnormalities and deteriorating renal function. They found that ultrasonography can be useful in the evaluation of CKD if they are used in conjunction with biochemical markers like eGFR [16]. The current study showed that the correlation of cortical thickness with renal function was stronger than renal length. This was also reported earlier by Beland et al., who found that ultrasound measurement of cortical thickness was a better predictor of GFR than was renal bipolar length. Renal length is a widely available parameter in routine ultrasonography, but it may not be able to accurately predict early nephron loss, as renal size may be preserved in early stages of CKD [17].The other significant result from the present study is that the cortical thickness progressively decreased across stages of CKD. Patients in stage 4 and stage 5 CKD showed significantly lower cortical thickness values than patients in earlier stages of the CKD. In recent studies, renal parenchymal and cortical assessment was done in patients with CKD, with severe renal disease also showing significant cortical thinning with a decrease in eGFR [18]. The pathophysiological basis of the cortical thinning in CKD is associated with progressive glomerulosclerosis, tubular atrophy, and interstitial fibrosis, and the destruction of nephrons. As the renal cortex is where the majority of glomeruli are located, this thinning is a reflection of loss of renal tissue. Thus, ultrasound measurement of the cortical thickness is a structural correlate of functional renal decline as measured by eGFR [19]. It is concluded that the present study brings to light the significance of ultrasonography in the field of health care in the condition of limited resources. Ultrasound is non-radiating, low-cost, widely available, and repeatable. Renal cortical thickness measurement is an easy procedure that can be performed in a standard renal ultrasound exam without special equipment or discomfort for the patient. This could aid the clinician using these factors to determine the severity of the CKD, to predict the progression of the disease, and to aid long-term monitoring of the patient [20].The present study had its limitations; however, the results were a significant discovery. This is a single-center, cross-sectional study, so causal relationships could not be determined. Furthermore, the interobserver variation of ultrasound measurements was not evaluated. Therefore, other multicenter trials with larger numbers of patients and prospective follow-up are recommended to confirm the predictive value of renal cortical thickness as an imaging biomarker in chronic kidney disease.

Limitations

This study was done in a single tertiary care centre on a relatively small population size, so findings may not be generalizable. The cross-sectional design did not allow for long-term follow-up and causal assessment. There was no interobserver variability to evaluate ultrasound measurements. It is recommended to use larger multicenter longitudinal studies to further validate this,

In chronic kidney disease patients, renal cortical thickness on ultrasonography was significantly correlated with eGFR. Thinning of the cortex was associated with worsening renal function, with a progression over time. Diagnostic ultrasound could be a simple, reliable, non-invasive, and cost-effective imaging modality for the evaluation and management of chronic kidney disease.

1. Chen X, Kong J, Pan J, Huang K, Zhou W, Diao X, Cai J, Zheng J, Yang X, Xie W, Yu H, Li J, Pei L, Dong W, Qin H, Huang J, Lin T. Kidney damage causally affects the brain cortical structure: A Mendelian randomization study. Biomedicine. 2021 Oct; 72:103592. doi: 10.1016/j.ebiom.2021.103592.
2. Meola M, Samoni S, Petrucci I. Imaging in Chronic Kidney Disease. Contra Nephrol. 2016; 188:69-80. doi: 10.1159/000445469.
3. Korkmaz M, Aras B, Guney S, Yılmaz M. Clinical significance of renal cortical thickness in patients with chronic kidney disease. Ultrasonography. 2018 Jan;37(1):50-54. doi: 10.14366/usg.17012.
4. Takata T, Koda M, Sugihara T, Sugihara S, Okamoto T, Miyoshi K, Ootsuka M, Fujis Y, Matano T, Okano J, Hosho K, Iyamu T, Fukui T, Fukuda S, Umemura C, Is Omoto H. Left Renal Cortical Thickness Measured by Ultrasound Can Predict Early Progression of Chronic Kidney Disease. Nephron. 2016;132(1):25-32. doi: 10.1159/000441957.
5. Gitomer B, Pereira R, Salesky IB, Stoneback JW, Isakova T, Cai X, Dalrymple LS, Ofsthun N, You Z, Malloch HH, Maddux F, George D, Torres V, Chapman A, Steinman TI, Wolf M, Chanchal M. Mineral bone disease in autosomal dominant polycystic kidney disease. Kidney Int. 2021 Apr;99(4):977-985. doi: 10.1016/j.kint.2020.07.041.
6. Vemuri P, Davey C, Johansen KL, Zuk SM, Reid RI, Thostenson KB, Reddy AL, Jack CR, Knapman DS, Murray AM. Chronic Kidney Disease Associated with Worsening White Matter Disease and Ventricular Enlargement. J Alzheimer’s Dis. 2021;83(4):1729-1740. doi: 10.3233/JAD-210604.
7. Purim M, Milani B, Pivin E, Prochaska A, Vogt B, Stuber M, Burner M. Reduced cortical oxygenation predicts a progressive decline of renal function in patients with chronic kidney disease. Kidney Int. 2018 Apr;93(4):932-940. doi: 10.1016/j.kint.2017.10.020.
8. Chang CY, Lin CC, Tsai CF, Yang WC, Wang SJ, Lin FH, Fuh JL. Cognitive impairment and hippocampal atrophy in chronic kidney disease. Acta Neurol Scand. 2017 Nov;136(5):477-485. doi: 10.1111/ane.12753.
9. Nakazato T, Kheira H, Limasawa T. An equation to estimate the renal cortex volume in chronic kidney disease patients. Clin Exp Nephrol. 2018 Jun;22(3):603-612. doi: 10.1007/s10157-017-1492-8.
10. Yamashita SR, von Azinger AC, Iared W, Bezerra AS, Ammirati AL, Canziani ME, D'Ippolito G. Value of renal cortical thickness as a predictor of renal function impairment in chronic renal disease patients. Radial Bras. 2015 Jan-Feb;48(1):12-6. doi: 10.1590/0100-3984.2014.0008.
11. Kodikara I, Gamage DTK, Nanayakkara G, Ilampirai I. Diagnostic performance of renal ultrasonography in detecting chronic kidney disease of various severity. Asian Biomed (Res Rev News). 2020 Oct 31;14(5):195-202. doi: 10.1515/abm-2020-0028.
12. Grossmann M, Tzschätzsch H, Lang ST, Guo J, Bruns A, Dürr M, Hoyer BF, Grittner U, Reichbauer M, Nguyen Trong M, Schultz M, Hamm B, Braun J, Sack I, Marticorena Garcia SR. US Time-Harmonic Elastography for the Early Detection of Glomerulonephritis. Radiology. 2019 Sep;292(3):676-684. doi: 10.1148/radiol.2019182574.
13. Milani B, Anzalone A, Sousa-Guimaraes S, Vakil Zadeh N, Paskowitz M, Vogt B, Stuber M, Burner M, Purim M. Reduction of cortical oxygenation in chronic kidney disease: evidence obtained with a new analysis method of blood oxygenation level-dependent magnetic resonance imaging. Nephrol Dial Transplant. 2017 Dec 1;32(12):2097-2105. doi: 10.1093/net/gfw362.
14. Gao J, Perlman A, Kalachi S, Berman N, Seshan S, Salvatore S, Smith L, Wehrli N, Waldron L, Kodali H, Chevalier J. Multiparametric Quantitative Ultrasound Imaging in Assessment of Chronic Kidney Disease. J Ultrasound Med. 2017 Nov;36(11):2245-2256. doi: 10.1002/jum.14209.
15. Leong SS, Wong JHD, Md Shah MN, Vijay Ananthan A, Jalalonmuhali M, Ng KH. Shear wave elastography in the evaluation of renal parenchymal stiffness in patients with chronic kidney disease. Br J Radiol. 2018 Sep;91(1089):20180235. doi: 10.1259/bjr.20180235.
16. Meng C, Jørgensen HS, Verlinden L, Braven Boer N, de Loor H, Daise PC, Carmelite G, Veniole P. Contemporary kidney transplantation has a limited impact on bone microarchitecture. Bone Rep. 2022 Feb 7; 16:101172. doi: 10.1016/j.bonr.2022.101172.
17. Cho EB, Shin HY, Park SE, Chun P, Jang HR, Yang JJ, Kim HJ, Kim YJ, Jung NY, Lee JS, Lee J, Jang YK, Jang EY, Kang M, Lee JM, Kim C, Min JH, Ryu S, Na DL, Seo SW. Albuminuria, Cerebrovascular Disease and Cortical Atrophy: among Cognitively Normal Elderly Individuals. Sci Rep. 2016 Feb 15; 6:20692. doi: 10.1038/srep20692.
18. Mishima T, Motoyama K, Imanishi Y, Hamamoto K, Nagata Y, Yamada S, Kuriyama N, Watanabe Y, Emoto M, Inaba M. Decreased cortical thickness, as estimated by a newly developed ultrasound device, as a risk for vertebral fracture in type 2 diabetes mellitus patients with eGFR of less than 60 mL/min/1.73 m2. Osteoporosis Int. 2015 Jan;26(1):229-36. doi: 10.1007/s00198-014-2843-x.
19. Ahmed S, Boggio S, Hassan M, Lal S, Ali M. Role of Ultrasound in the Diagnosis of Chronic Kidney Disease and its Correlation with Serum Creatinine Level. Cureus. 2019 Mar 12;11(3): e4241. doi: 10.7759/cureus.4241.
20. Hassan K, Lobe rant N, Abbas N, Fadi H, Shadia H, Khazim K. Shear wave elastography imaging for assessing the chronic pathologic changes in advanced diabetic kidney disease. Ther Clin Risk Manag. 2016 Nov 7; 12:1615-1622. doi: 10.2147/TCRM.S118465.l