Chronic kidney disease (CKD) is defined by abnormalities of kidney structure or function persisting for at least three months and having implications for health. Contemporary Kidney Disease: Improving Global Outcomes (KDIGO) recommendations classify CKD according to cause, glomerular filtration rate category and albuminuria category. Evaluation of CKD therefore integrates clinical information, biochemical measurements, urine findings and evidence of structural renal abnormalities.[1] Serum creatinine remains one of the most widely used biochemical markers for routine assessment of kidney function and is incorporated into commonly used equations for estimating glomerular filtration rate. However, serum creatinine concentration is influenced by several non-renal determinants, including age, sex, muscle mass and dietary factors. Consequently, serum creatinine alone does not adequately characterize the structural extent or chronicity of renal disease.[1,2] Renal ultrasonography provides a readily available and non-invasive method for structural assessment of the kidneys. It permits evaluation of renal dimensions, cortical characteristics, corticomedullary differentiation and abnormalities such as cystic disease and urinary tract obstruction. Structural findings on ultrasonography may therefore complement biochemical measures when evaluating patients with established CKD.[1] Among routinely evaluated sonographic characteristics, renal cortical echogenicity has particular clinical relevance. Increased cortical echogenicity is associated with renal parenchymal abnormalities, although it is not specific for an individual renal disease. In a biopsy-correlated study, Moghazi et al. demonstrated significant relationships between renal cortical echogenicity and histopathological abnormalities including glomerulosclerosis, tubular atrophy, interstitial fibrosis and interstitial inflammation.[3] A practical semiquantitative approach to assessment of renal cortical echogenicity involves comparison of the renal cortex with adjacent hepatic or splenic parenchyma. Progressive increases in renal cortical echogenicity, particularly when accompanied by impairment of corticomedullary differentiation, may indicate increasing renal parenchymal abnormality. Siddappa et al. demonstrated a statistically significant positive relationship between sonographic echogenicity grade and serum creatinine in patients with CKD.[4] Renal dimensions constitute another important component of ultrasonographic assessment. Progressive chronic parenchymal injury may eventually be accompanied by cortical loss and reduction in renal size. Nevertheless, renal length alone has limitations because renal dimensions may vary according to demographic and clinical characteristics and the underlying cause of renal disease. Beland et al. investigated renal cortical thickness and renal length as ultrasonographic indicators of renal function in CKD and found cortical thickness to have a stronger relationship with renal function than renal length.[5] Korkmaz et al. subsequently demonstrated significant relationships between estimated glomerular filtration rate and both renal length and cortical thickness, with cortical thickness demonstrating the stronger association.[6] Yamashita et al. also evaluated renal cortical thickness, parenchymal thickness and bipolar renal length in patients with chronic renal disease. Cortical thickness demonstrated a stronger correlation with renal function than bipolar renal length, further indicating that renal dimensions and parenchymal measurements provide related but distinct structural information.[7] Quantitative assessment of renal echogenicity has also been investigated as a means of reducing some of the subjectivity inherent in conventional ultrasonographic grading. Libório et al. evaluated quantitative renal echogenicity in patients with glomerular disease and demonstrated its potential utility in identifying advanced CKD.[8] A multiparametric approach may further improve the relationship between ultrasonographic findings and renal dysfunction. Araújo et al. evaluated kidney measurements together with cortical echogenicity and histological findings and demonstrated that weighting renal measurements according to cortical echogenicity improved their ability to identify renal dysfunction and chronic histological abnormalities.[9] More recently, Garg et al. reported significant relationships between renal function and sonographically measured renal length, cortical thickness and renal volume among adults with newly diagnosed CKD. Renal volume demonstrated the strongest correlation with estimated glomerular filtration rate in their study, supporting the use of multiple structural parameters rather than reliance on renal length alone.[10] Taken together, available evidence indicates that renal cortical echogenicity and renal dimensions provide complementary structural information in CKD. However, these parameters may not change in parallel, and their relationships with biochemical renal dysfunction may differ. The present study was therefore undertaken to evaluate the association of renal cortical echogenicity and renal length with serum creatinine levels among adults with chronic kidney disease. AIM To evaluate the relationship between renal ultrasonographic parameters and serum creatinine levels in adult patients with chronic kidney disease. OBJECTIVES 1. To assess the distribution of renal cortical echogenicity grades and renal length among adults with chronic kidney disease. 2. To determine the association and correlation of renal cortical echogenicity and renal length with serum creatinine and selected clinical risk factors in chronic kidney disease.

Study Design and Setting This was a retrospective cross-sectional observational study conducted using the medical and radiological records of adult patients with chronic kidney disease attending the renal outpatient clinic of Mahavir Institute of Medical Sciences , over a period of one year from May 2025 to April 2026. The study used a retrospective cross-sectional design in adult CKD patients and evaluated renal echogenicity, renal length, corticomedullary differentiation, serum creatinine, and estimated glomerular filtration rate. Study Population A total of 80 adult patients with chronic kidney disease who fulfilled the predefined eligibility criteria were included in the study. Patients were identified from renal outpatient and radiology records. Inclusion Criteria 1. Adults aged ≥18 years. 2. Patients diagnosed with chronic kidney disease according to accepted KDIGO criteria. 3. Patients with available serum creatinine measurements. 4. Patients who had undergone renal ultrasonography. 5. Patients with adequately documented renal echogenicity and renal dimensions. Exclusion Criteria Patients with the following conditions were excluded: 1. Advanced cystic renal disease. 2. Hydronephrosis. 3. Fatty liver detected on ultrasonography. 4. Other significant hepatic disease affecting comparison of renal and hepatic echogenicity. 5. Incomplete biochemical or ultrasonographic records. 6. Normal renal echogenicity corresponding to Grade 0. Data Collection A structured data collection form was used to record: • Age • Sex • Relevant anthropometric characteristics • Etiology and clinical risk factors for CKD • Presence of diabetes mellitus • Presence of hypertension • Serum creatinine • Estimated glomerular filtration rate • Right renal length • Left renal length • Renal cortical echogenicity • Corticomedullary differentiation Estimated glomerular filtration rate was calculated using the CKD-EPI equation. Ultrasonographic Assessment Renal ultrasonographic findings were obtained from radiological records. The following parameters were evaluated: • Renal cortical echogenicity • Corticomedullary differentiation • Right kidney length • Left kidney length Grading of Renal Echogenicity Renal cortical echogenicity was graded in relation to liver echogenicity and preservation of corticomedullary differentiation. Grade 0: Renal cortical echogenicity less than liver echogenicity with preserved corticomedullary differentiation. Grade 1: Renal cortical echogenicity similar to liver echogenicity with preserved corticomedullary differentiation. Grade 2: Renal cortical echogenicity greater than liver echogenicity with preserved corticomedullary differentiation. Grade 3: Renal cortical echogenicity greater than liver echogenicity with poorly preserved corticomedullary differentiation. Grade 4: Renal cortical echogenicity greater than liver echogenicity with loss of corticomedullary differentiation. Participants with Grade 0 echogenicity were excluded. Outcome Measures The primary outcome was the relationship between renal cortical echogenicity grade and serum creatinine concentration. Secondary outcomes included: • Association between kidney length and serum creatinine. • Relationship between kidney length and renal echogenicity grade. • Differences in renal length according to diabetes mellitus and hypertension. • Predictive relationship between renal echogenicity and serum creatinine. Statistical Analysis Data were analyzed using an appropriate statistical software package.Continuous variables were expressed as mean ± standard deviation, while categorical variables were presented as frequencies and percentages.One-way analysis of variance was used to compare serum creatinine and renal length across renal echogenicity grades.Pearson's correlation coefficient was used to assess the relationship between serum creatinine and renal length.Linear regression analysis was used to assess whether renal echogenicity independently predicted serum creatinine concentration.Independent-samples tests were used where appropriate to compare renal length between participants with and without diabetes mellitus and hypertension.A two-tailed p-value <0.05 was considered statistically significant.

Baseline Characteristics A total of 80 adult patients with chronic kidney disease were included in the study. The mean age of the study population was 45.3 ± 15.7 years. Of the 80 participants, 56 (70.0%) were male and 24 (30.0%) were female, giving a male-to-female ratio of approximately 2.3:1. Table 1. Baseline demographic characteristics of the study participants Characteristic Value Total participants 80 Age (years), mean ± SD 45.3 ± 15.7 Male, n (%) 56 (70.0) Female, n (%) 24 (30.0) Male ratio 2.3:1 Distribution of Renal Cortical Echogenicity Grades Grade 4 renal cortical echogenicity was the most frequently observed abnormality and was present in 40 (50.0%) patients. Grade 3 was observed in 24 (30.0%), Grade 2 in 9 (11.3%) and Grade 1 in 7 (8.8%) patients. Overall, 64 of the 80 participants (80.0%) had Grade 3 or Grade 4 renal cortical echogenicity. Table 2. Distribution of renal cortical echogenicity grades Echogenicity grade n % Grade 1 7 8.8 Grade 2 9 11.3 Grade 3 24 30.0 Grade 4 40 50.0 Total 80 100.0* *Percentages may differ marginally from 100% because of rounding. Serum Creatinine According to Renal Cortical Echogenicity Grade Serum creatinine increased progressively with increasing renal cortical echogenicity. Mean serum creatinine was 3.4 ± 1.3 mg/dL in Grade 1, 4.8 ± 2.0 mg/dL in Grade 2, 6.8 ± 3.0 mg/dL in Grade 3 and 9.4 ± 2.8 mg/dL in Grade 4. The weighted overall mean serum creatinine based on the grade-specific distribution was approximately 7.58 mg/dL. The progressive increase across the four echogenicity categories demonstrated a clear structural–biochemical gradient. Table 3. Serum creatinine according to renal cortical echogenicity grade Echogenicity grade n Serum creatinine (mg/dL), mean ± SD Grade 1 7 3.4 ± 1.3 Grade 2 9 4.8 ± 2.0 Grade 3 24 6.8 ± 3.0 Grade 4 40 9.4 ± 2.8 Renal Length According to Renal Cortical Echogenicity Grade Renal length showed comparatively modest variation across increasing echogenicity grades. Right renal length decreased from 10.34 ± 1.42 cm in Grade 1 to 9.92 ± 1.34 cm in Grade 4. Left renal length ranged from 10.67 ± 1.19 cm in Grade 1 to 10.04 ± 1.44 cm in Grade 4. Based on the grade-specific sample sizes, the weighted mean right and left renal lengths were approximately 10.00 cm and 10.19 cm, respectively. Table 4. Right and left renal length according to renal cortical echogenicity grade Echogenicity grade n Right renal length (cm), mean ± SD Left renal length (cm), mean ± SD Grade 1 7 10.34 ± 1.42 10.67 ± 1.19 Grade 2 9 10.10 ± 1.29 10.09 ± 1.31 Grade 3 24 10.00 ± 1.30 10.35 ± 1.27 Grade 4 40 9.92 ± 1.34 10.04 ± 1.44 Weighted mean 80 10.00 10.19 The variation in renal length across echogenicity grades was substantially less pronounced than the corresponding progressive increase in serum creatinine. Correlation Between Renal Length and Serum Creatinine Both right and left renal lengths demonstrated weak inverse relationships with serum creatinine. The inverse relationship was slightly greater for the left kidney than for the right kidney. Table 5. Correlation between renal length and serum creatinine Parameter Correlation coefficient (r) Strength/direction Left renal length vs serum creatinine −0.235 Weak inverse correlation Right renal length vs serum creatinine −0.195 Weak inverse correlation These findings indicate that increasing serum creatinine was associated with a tendency toward decreasing renal length; however, the magnitude of the relationship was weak.

The present study evaluated the relationship of renal cortical echogenicity and renal length with serum creatinine in 80 adults with chronic kidney disease. The principal finding was a progressive increase in serum creatinine with increasing grades of renal cortical echogenicity. Mean serum creatinine increased from 3.4 ± 1.3 mg/dL in Grade 1 to 4.8 ± 2.0 mg/dL in Grade 2, 6.8 ± 3.0 mg/dL in Grade 3 and 9.4 ± 2.8 mg/dL in Grade 4. In contrast, renal length showed comparatively little variation across echogenicity grades, and its relationship with serum creatinine was weak. These findings indicate that cortical echogenicity may reflect functional deterioration more closely than longitudinal renal length alone. The distribution of echogenicity grades also demonstrated a predominance of advanced sonographic abnormalities. Grade 4 changes were present in 50.0% of participants and Grade 3 changes in 30.0%, resulting in 80.0% of the study population having Grade 3 or Grade 4 renal cortical echogenicity. This pattern indicates that substantial structural renal abnormality was common in the study population and should be considered when interpreting the magnitude of the observed biochemical abnormalities. A recent study by Kausar et al. evaluated 200 patients with CKD and specifically examined the association of renal cortical echogenicity and renal length with serum creatinine. Serum creatinine increased progressively across cortical echogenicity grades, from approximately 1.92 mg/dL in Grade 1 to 6.00 mg/dL in Grade 4. The investigators also reported a weak negative correlation between renal length and serum creatinine (r = −0.144). Their findings are particularly relevant to the present study because they demonstrate the same overall pattern: a pronounced relationship between increasing cortical echogenicity and serum creatinine accompanied by a substantially weaker relationship between longitudinal renal size and renal dysfunction.[11] This distinction between echogenicity and renal length is clinically important. Progressive CKD is associated with structural alterations within the renal parenchyma, but these changes do not necessarily produce a proportional reduction in total renal length. Renal dimensions are influenced by several additional factors, including body size, age, sex and the underlying renal disease. Consequently, relatively preserved renal dimensions cannot be assumed to indicate preserved renal function. The findings are further supported by the recent study of Getaneh et al., who evaluated grayscale ultrasonographic characteristics in 103 patients with stage III or more advanced CKD. Mean renal length was 8.97 ± 1.42 cm, while mean parenchymal and cortical thicknesses were 1.36 ± 0.45 cm and 0.85 ± 0.27 cm, respectively. Average renal length demonstrated only a modest positive correlation with estimated glomerular filtration rate (r = 0.26, p = 0.009), whereas increasing renal cortical echogenicity demonstrated a significant inverse relationship with eGFR (p <0.001).[12] Their observations support the concept that renal length provides useful structural information but may have a relatively limited relationship with the degree of functional impairment when considered in isolation. In the present analysis, right renal length decreased only modestly from 10.34 ± 1.42 cm in Grade 1 to 9.92 ± 1.34 cm in Grade 4. Similarly, left renal length changed from 10.67 ± 1.19 cm in Grade 1 to 10.04 ± 1.44 cm in Grade 4. The weighted mean right and left renal lengths were approximately 10.00 cm and 10.19 cm, respectively. Thus, despite the marked increase in serum creatinine across echogenicity grades, overall renal length remained relatively preserved. The weak inverse correlations between serum creatinine and left and right renal length (r = −0.235 and r = −0.195, respectively) are consistent with this observation. Renal length therefore appears to represent only one component of the structural changes occurring in CKD. Measurements of cortical thickness, parenchymal thickness and renal volume may provide additional information and should be considered in future studies. An important development in renal ultrasonography is the movement from subjective visual assessment toward quantitative evaluation of renal echogenicity. Zhao et al. recently investigated quantitative renal echogenicity in 339 patients. Visual interpretation by radiologists showed relatively limited diagnostic accuracy, whereas quantitative differences in echogenicity between the renal cortex and renal sinus demonstrated substantially better diagnostic performance. The right renal sinus-to-cortex echogenicity difference achieved an area under the receiver operating characteristic curve of 0.838, while the corresponding left-sided measurement achieved an area under the curve of 0.805.[13] These findings suggest that objective quantification of renal echogenicity may eventually overcome some of the limitations associated with conventional visual grading. This observation has direct implications for the interpretation of the present study. Conventional grading of cortical echogenicity is clinically practical and can be performed during routine ultrasonography, but it remains partly subjective. Image gain, dynamic range, transducer characteristics, patient habitus, operator experience and characteristics of the reference organ may influence visual assessment. Quantitative techniques may therefore improve reproducibility and facilitate longitudinal comparison. The use of hepatic echogenicity as a reference also requires careful consideration. Diffuse hepatic abnormalities, particularly fatty infiltration, can alter hepatic echogenicity and potentially affect renal-to-hepatic comparison. Exclusion of significant hepatic abnormalities is therefore methodologically important when a liver-based comparison is used for renal cortical grading. The contemporary evidence base increasingly supports interpretation of renal ultrasonography as a multiparametric examination rather than reliance on a single measurement. Rubio Menéndez and Rivera Gorrín reviewed the relationship between renal ultrasonographic parameters and CKD stage and emphasized that renal length, parenchymal thickness, parenchymal echogenicity and intrarenal Doppler parameters provide different but complementary information. They also highlighted evidence supporting composite ultrasonographic approaches that integrate renal dimensions with parenchymal characteristics.[14] Their review is particularly relevant to the present findings because it reinforces the limitations of interpreting renal length independently. Renal length adjusted for body size and corrected parenchymal measurements may demonstrate stronger relationships with renal function than unadjusted longitudinal length. Echogenicity, meanwhile, appears to reflect a different aspect of renal structural abnormality and has repeatedly demonstrated associations with declining renal function.[14] The findings of the present study therefore support a structural-functional approach to CKD assessment. Serum creatinine reflects renal function but is influenced by non-renal determinants and does not directly characterize renal morphology. Ultrasonography provides information regarding renal structure but cannot independently quantify glomerular filtration. The two assessments should consequently be regarded as complementary rather than interchangeable. The progressive increase in serum creatinine across renal cortical echogenicity grades observed in this study is clinically relevant because echogenicity can be assessed during routine renal ultrasonography without additional invasive procedures. Nevertheless, increasing cortical echogenicity should not be interpreted as a specific histopathological diagnosis. Different chronic renal diseases can produce similar sonographic appearances, and the underlying etiology must be established using the complete clinical, biochemical and, where indicated, pathological evaluation. Similarly, preservation of renal length should not be interpreted as evidence against substantial renal dysfunction. The relatively small differences in renal length across echogenicity grades in the present study, despite a marked increase in serum creatinine, illustrate this limitation. The findings also have implications for future research. Standardized renal ultrasonographic protocols incorporating bilateral renal length, cortical thickness, parenchymal thickness, corticomedullary differentiation and quantitative echogenicity may provide a more comprehensive structural assessment than conventional renal length alone. Integration of these parameters with eGFR and albuminuria could permit more meaningful assessment of their relationships with CKD severity. Prospective longitudinal studies would be particularly valuable because the present cross-sectional design cannot determine the temporal sequence between increasing cortical echogenicity and deterioration in renal function. Serial ultrasonographic measurements could establish whether changes in quantitative echogenicity, cortical thickness or renal dimensions predict subsequent decline in eGFR or progression to advanced CKD. Overall, the present findings are consistent with recent evidence demonstrating that increasing renal cortical echogenicity accompanies worsening renal dysfunction, whereas renal length has a weaker and more variable relationship with functional impairment. [11–14] Contemporary research additionally suggests that quantitative echogenicity and multiparametric ultrasonographic assessment may improve the objectivity and clinical utility of renal imaging in CKD.

Increasing renal cortical echogenicity demonstrated a progressive relationship with worsening biochemical renal dysfunction. Mean serum creatinine increased from 3.4 ± 1.3 mg/dL in Grade 1 to 9.4 ± 2.8 mg/dL in Grade 4 renal cortical echogenicity. In contrast, right and left renal lengths showed comparatively small variations across increasing echogenicity grades and demonstrated only weak inverse relationships with serum creatinine. These findings suggest that renal cortical echogenicity may provide more useful structural information regarding the severity of renal parenchymal abnormality than longitudinal renal length alone. Renal ultrasonography should nevertheless complement rather than replace biochemical assessment of renal function. Integration of clinical findings, serum and urine biomarkers and renal imaging remains necessary for comprehensive assessment of CKD. Future studies incorporating quantitative renal echogenicity, cortical and parenchymal thickness, renal volume and longitudinal renal-function measurements may improve the objectivity and prognostic utility of renal ultrasonography in chronic kidney disease.

1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117-S314. doi:10.1016/j.kint.2023.10.018. 2. Chen TK, Knicely DH, Grams ME. Chronic kidney disease diagnosis and management: a review. JAMA. 2019;322(13):1294-1304. doi:10.1001/jama.2019.14745. 3. Moghazi S, Jones E, Schroepple J, Arya K, McClellan W, Hennigar RA, et al. Correlation of renal histopathology with sonographic findings. Kidney Int. 2005;67(4):1515-1520. doi:10.1111/j.1523-1755.2005.00230.x. 4. Siddappa JK, Singla S, Al Ameen M, Rakshith SC, Kumar N. Correlation of ultrasonographic parameters with serum creatinine in chronic kidney disease. J Clin Imaging Sci. 2013;3:28. doi:10.4103/2156-7514.114809. 5. Beland MD, Walle NL, Machan JT, Cronan JJ. Renal cortical thickness measured at ultrasound: is it better than renal length as an indicator of renal function in chronic kidney disease? AJR Am J Roentgenol. 2010;195(2):W146-W149. doi:10.2214/AJR.09.4104. 6. Korkmaz M, Aras B, Güneyli S, Yılmaz M. Clinical significance of renal cortical thickness in patients with chronic kidney disease. Ultrasonography. 2018;37(1):50-54. doi:10.14366/usg.17012. 7. Yamashita SR, von Atzingen AC, Iared W, Bezerra ASA, Ammirati AL, Canziani MEF, et al. Value of renal cortical thickness as a predictor of renal function impairment in chronic renal disease patients. Radiol Bras. 2015;48(1):12-16. doi:10.1590/0100-3984.2014.0008. 8. Libório AB, Neves FMO, Melo CBT, Leite TT, Leitão RA. Quantitative renal echogenicity as a tool for diagnosis of advanced chronic kidney disease in patients with glomerulopathies and no liver disease. Kidney Blood Press Res. 2017;42(4):708-716. doi:10.1159/000484105. 9. Araújo NC, Rebelo MAP, Rioja LS, Suassuna JHR. Sonographically determined kidney measurements are better able to predict histological changes and a low CKD-EPI eGFR when weighted towards cortical echogenicity. BMC Nephrol. 2020;21:123. doi:10.1186/s12882-020-01789-7. 10. Garg A, Jhobta A, Kapila S, Rathour D. Correlation of sonographic parameters with renal function in patients with newly diagnosed chronic kidney disease. J Ultrason. 2022;22(91):e216-e221. doi:10.15557/jou.2022.0036. 11. Kausar S, Fareed F, Fatima K, Jahanzeb Z, Rehman HU. The association of renal cortical echogenicity and length with serum creatinine in patients with chronic kidney disease. Ann King Edw Med Univ. 2023;29(4):356-360. doi:10.21649/akemu.v23i4.5102. 12. Getaneh FH, Kassa BF, Amha LG, Getaneh FB. Ultrasound characteristics and correlation with estimated glomerular filtration rate in patients with chronic kidney disease: a facility-based cross-sectional study. J Int Med Res. 2025;53(3). doi:10.1177/03000605251327484. 13. Zhao L, Shang J, Shi Y, Yan Y, Li P, Niu W, et al. Quantifying ultrasound echogenicity difference for accurate chronic kidney disease diagnosis. J Nephrol. 2025;38(8):2353-2362. doi:10.1007/s40620-025-02352-z. 14. Rubio Menéndez V, Rivera Gorrín M. Correlation of renal ultrasound parameters with chronic kidney disease stage. Nefrologia (Engl Ed). 2026;46(3):501450. doi:10.1016/j.nefroe.2026.501450.