Comparison of serum creatinine, point-of-care symmetric dimethylarginine and renal imaging with glomerular filtration rate measured by renal scintigraphy in healthy and early chronic kidney diseased cats.

The aim of this study was to evaluate routinely used tests to diagnose cats in early stages of chronic kidney disease (CKD) and to describe a model for evaluating these variables simultaneously. Apparently healthy cats were screened using serum creatinine (sCr), point-of-care symmetric dimethylarginine (POC SDMA), urinalysis, urine protein/creatinine ratio (UPC) and imaging evaluation. Those parameters were compared to glomerular filtration rate (GFR) assessed by renal scintigraphy. Forty-four cats were included and consisted of 14 (31.8%) healthy cats (absence of abnormalities in renal morphology and sCr less than 1.6 mg/dL), 20 (45.5%) cats classified as CKD I (presence of abnormalities in renal morphology and sCr less than 1.6 mg/dL) and ten (22.7%) as CKD II (sCr equal to or greater than 1.6 mg/dL, with or without abnormalities in renal morphology). A large number (40.9%) of apparently healthy cats presented reduction in GFR, which included half of CKD I patients. Point-of-care SDMA was not a good predictor for decreased GFR, nor was it correlated with the variables GFR and sCr. Glomerular filtration rate was significantly lower in CKD I and II groups in comparison with healthy cats, but there was no significant difference between the CKD I and II groups. Multivariate logistic regression model identified three variables that affected the odds of a cat having decreased GFR (< 2.5 mL/min/kg): sCr (OR = 18.3; p = 0.019; CI = 1.6-207.2), and the ultrasonographic findings 'reduced corticomedullary definition' (OR = 19.9; p = 0.022; CI = 1.6-254.0) and 'irregular contour' (OR = 65.6; p = 0.003; CI = 4.2-1038.2). Renal ultrasonography evaluation should always be considered for screening early CKD in apparently healthy cats.

Can distinction between the renal cortex and outer medulla on ultrasonography predict estimated glomerular filtration rate in canine chronic kidney diseases?

BACKGROUND: Quantitative evaluation of renal cortical echogenicity (RCE) has been tried and developed in human and veterinary medicine. OBJECTIVES: The objective of this study was to propose a method for evaluating RCE quantitatively and intuitively, and to determine associations between ultrasonographic renal structural distinction and estimated glomerular filtration rate (eGFR) in canine chronic kidney disease (CKD). METHODS: Data were collected on 63 dogs, including 27 with normal kidney function and 36 CKD patients. Symmetric dimethylarginine and creatinine concentrations were measured for calculating eGFR. RCE was evaluated as 3 grades on ultrasonography images according to the distinction between the renal cortex and outer medulla. The RCE grade of each kidney was measured. RESULTS: There was a significant difference in eGFR between the group normal and CKD (p < 0.001). As mean of RCE grades (the mean values of each right and left kidney's RCE grade) increases, the proportion of group CKD among the patients in each grade increases (p < 0.001). Also, severity of RCE (classified as "high" if any right or left kidney evaluated as RCE grade 3, "low" otherwise) and eGFR is good indicator for predicting group CKD (p < 0.001). CONCLUSIONS: The degree of distinction between the renal cortex and the outer medulla is closely related to renal function including eGFR and the RCE grade defined in this study can be used as a method of objectively evaluating RCE.

Sonographically determined kidney measurements are better able to predict histological changes and a low CKD-EPI eGFR when weighted towards cortical echogenicity.

BACKGROUND: The renal length and cortical echogenicity have shown correlation to the renal function and histological changes in CKD patients. The aim of this study was to assess the accuracy of crude and composite ultrasound parameters based on kidney measurements and cortical echogenicity to detect renal dysfunction and histological changes. METHODS: Kidney sonography and biopsy were performed in 112 patients. Histological changes were graded in 0, < 25%, ≥25%, ≤50 and > 50% of the sample. Cortical echogenicity was graded relative to liver or spleen parenchyma: less than, equal to and higher than the liver/spleen. Kidney length, the kidney length/body height ratio (KL/H) and cortical thickness were obtained. Each parameter was multiplied by a cortical echogenicity-weighting arbitrary factor: 1.17, 1 or 0.69 for cortex less than, equal to or higher than the liver, respectively. The GFR was estimated using the CKD-EPI formula. The accuracy of crude and composite parameters to identify patients with a high creatinine, a low GFR and histological changes were evaluated. RESULTS: The discriminative power of kidney length and cortical thickness for renal dysfunction and histological changes was improved after weighting for cortical echogenicity. However, the best discriminative was the kidney length to height ratio weighted towards renal echogenicity (w-KL/H). CONCLUSION: w-KL/H exceeded the other parameters as a marker of renal impairment and histological changes in CKD. Calculation of the w-KL/H index may be of help as a non-invasive tool to identify patients with significant renal disease and might be useful to guide therapeutic decisions.

Doença parenquimatosa renal: correlação histológico-sonográfica / Renal parenchymal disease: histopathologic-sonographic correlation

OBJETIVO: Este estudo foi planejado para avaliar a correlação da ecografia do rim com as lesões histológicas e com os achados clínico-laboratoriais na doença parenquimatosa renal, por análise de regressão logística multivariada. MÉTODOS: Os dados clínicos, laboratoriais, ecográficos e as biópsias foram avaliados em 154 pacientes. A ecogenicidade cortical foi graduada como menor que grau zero, igual a grau um ou maior que grau dois a do parênquima hepático ou esplênico. As lesões histológicas - proliferação mesangial (PM), permeação leucocitária (PL), crescente e necrose fibrinóide (CNF), infiltrado inflamatório intersticial (II), esclerose glomerular segmentar (ES), obsolescência glomerular (OG), atrofia tubular (AT), fibrose intersticial (FI) e edema intersticial (EI) - foram graduadas de acordo com a extensão, em normal (0 por cento), leve (<25 por cento), moderada (>25 por cento <50 por cento), e grave (>50 por cento). RESULTADOS: a) II, FI, ES, EI e creatinina elevada ocorreram menos no grau 0 de ecogenicidade cortical; b) PM, hipertensão arterial e espessura normal do parênquima foram preditores do grau 1 de ecogenicidade cortical; c) FI, EI, creatinina elevada e parênquima fino foram preditores do grau 2 de ecogenicidade cortical; d) Excluindos os obesos, em jovens com hematócrito baixo, a pirâmide proeminente foi mais comum; e) Creatinina elevada e OG foram preditores de rins pequenos. CONCLUSÃO: A ecogenicidade cortical foi um sensível marcador de doença parenquimatosa renal. Lesões distintas mais do que o grau de severidade da lesão contribuiram para o aumento da ecogenicidade cortical. O EI aumenta exponencialmente o efeito da FI na ecogenicidade cortical.

PURPOSE: This study was designed to address the correlation between sonography of a kidney with histological lesions and clinical findings in patients with renal parenchymal disease based on a multivariate logistic regression analysis. METHODS: Clinical and laboratory data, sonograms and renal biopsies were evaluated in 154 patients. Cortical echogenicity was graded as less than (0), equal to (1) or greater than (2) liver/spleen parenchyma. Histological lesions - mesangial proliferation (MP), leukocyte permeation (LP), fibrinoid necrosis and crescents (FNC), interstitial infiltrate (II), segmental glomerular sclerosis (SGS), glomerular obsolescence (GO), tubular atrophy (TA) interstitial fibrosis (IF) and interstitial edema (IE) - were graded according to extension and severity as normal (0 percent), mild (<25 percent), moderate (>25 percent <50 percent), and severe (>50 percent). RESULTS: a) II, IF, SGS, IE and increased creatinine occurred less in cortical echogenicity grade 0; b) MP, arterial hypertension and normal parenchymal thickness predict cortical echogenicity grade 1; c) IF, IE, increased creatinine and thin parenchyma predict occurrence of echogenicity grade 2; d) Excluding obese patients, both youth and hematocrit accounted for pyramid prominence; e) increased creatinine and GO was probable in patients with small kidneys. CONCLUSIONS: Increased cortical echogenicity was a very sensitive marker of renal parenchymal disease. Different lesions rather than degree of lesion severity accounted for progressive increase of cortical echogenicity. IE exponentially increased the effect of IF on cortical echogenicity.