How histopathological diagnosis interacts with kidney ultrasound parameters and glomerular filtration rate

Abstract

The evaluation of estimated GFR (eGFR) is a pivotal staging step in patients with chronic kidney disease (CKD), and renal ultrasound plays an important role in diagnosis, prognosis and progression of CKD. The interaction between histopathological diagnosis and ultrasound parameters in eGFR determination has not been fully investigated yet. The study examined the results of native kidney biopsies performed in 48 Italian centers between 2012 and 2020. The primary goal was if and how the histopathological diagnosis influences the relationship between ultrasound parameters and eGFR. After exclusion of children, patients with acute kidney injury and patients without measure of kidney length or parenchymal thickness, 2795 patients have been selected for analysis. The median values were 52 years for patient age, 11 cm for bipolar kidney diameter, 16 mm for parenchymal thickness, 2.5 g/day for proteinuria and 70 ml/min/1.73 m² for eGFR. The bipolar kidney diameter and the parenchymal thickness were directly related with eGFR values (R square 0.064). Diabetes and proteinuria were associated with a consistent reduction of eGFR, improving the adjusted R square up to 0.100. Addition of histopathological diagnosis in the model increased the adjusted R square to 0.216. There is a significant interaction between histopathological diagnosis and longitudinal kidney diameter (P 0.006). Renal bipolar length and parenchymal thickness are directly related with eGFR. The magnitude of proteinuria and histopathological kidney diagnosis are associated with eGFR. The relationship between kidney length and the level of eGFR depends on the nature of the kidney disease.

Keywords: Chronic; Diabetes mellitus; Histology; Kidney failure; Proteinuria; Ultrasonography.

Fig. 1

Selection of study sample. The final analysed sample of 2795 patients was selected from a pool of 5312 biopsied patients, after exclusion of children, patients with acute kidney injury (AKI) or AKI on chronic kidney disease (CKD) and patients without measure of kidney length or parenchymal thickness

Fig. 2

Distribution of mean eGFR values by the histopathological diagnosis, at the time of kidney biopsy. Some histopathological diagnoses were associated with a near normal eGFR value, as in cases of normal kidney, minimal chance disease (MCD) or hereditary glomerulopathies. On the other side, other diseases, as small vessel vasculitis and myeloma cast nephropathy were more frequently associated with low eGFR values

Fig. 3

Inverse relationship between renal pathology score and marginal mean eGFR, after taking into the account the covariates of the multivariate analysis of the full model reported in the Panel B of Table 4. Renal Pathology score, according to reference [20], indicates the progressive severity of diabetic nephropathy from 1 to 4