The Clinical Utility of Kidney Cortical Thickness in assessing severity of CKD in Low Income Setting

Renal Ultrasound Scan (RUS) is known to have an important role in assessing kidney function in healthy people and people with Chronic Kidney Disease (CKD) with the kidney length (KL) being the most commonly used measure. The Glomerular Filtration Rate (GFR) is the gold standard in kidney function assessment and its strength of correlation with a RUS measure is used in ascertaining the reliability of that RUS measure.

To compare the strength of correlations between the GFR and RUS measures like KL and cortical thickness (CT) in healthy people and people with CKD.

One hundred and forty study participants who had kidney ultrasound scan were studied. Creatinine based GFR was determined and linear correlation coefficients (r) were used to determine the relationship between the GFR and RUS measures.

Seventy CKD cohorts with stage 2-4 disease and 70 healthy volunteers (each with 35 males and 35 females) took part. The total mean eGFR, KL and CT for the study participants were 70.5 ± 12.5ml/min, 10.0 ± 3.1cm, and 8.6 ± 2.7mm respectively. There was a progressive decline in eGFR and renal CT as CKD worsened down the stages. The mean eGFR, KL and CT of the CKD cohorts were 44.7 + 3.6 ml/min, 9.1 + 3.3 cm and 7.4 + 2.4 mm respectively. Among the CKD cohorts, the eGFR was highest in CGN and, the KL and CT were highest in obstructive uropathy. The GFR, was positively correlated with KL and CT, the strength of association being more with the CT. The mean age and GFR independently predicted the kidney cortical thickness.

Kidney sizes were smaller in females, with aging and with declining kidney function. The CT being more positively correlated with GFR than the KL, is a more reliable RUS measure in assessing kidney function.