Can measurement of the foetal renal parenchymal thickness with ultrasound be used as an indirect measure of nephron number?

Abstract

Chronic kidney disease continues to be under recognised and is associated with a significant global health burden and costs. An adverse intrauterine environment may result in a depleted nephron number and an increased risk of chronic kidney disease. Antenatal ultrasound was used to measure the foetal renal parenchymal thickness (RPT), as a novel method to estimate nephron number. Foetal renal artery blood flow was also assessed. This prospective, longitudinal study evaluated the foetal kidneys of 102 appropriately grown and 30 foetal growth-restricted foetuses between 20 and 37 weeks gestational age (GA) to provide vital knowledge on the influences foetal growth restriction has on the developing kidneys. The foetal RPT and renal artery blood flow were measured at least every 4 weeks using ultrasound. The RPT was found to be significantly thinner in growth-restricted foetuses compared to appropriately grown foetuses [likelihood ratio (LR) = 21.06, P ≤ 0.0001] and the difference increases with GA. In foetuses with the same head circumference, a growth-restricted foetus was more likely to have a thinner parenchyma than an appropriately grown foetus (LR = 8.9, P = 0.0028), supporting the principle that growth-restricted foetuses preferentially shunt blood towards the brain. No significant difference was seen in the renal arteries between appropriately grown and growth-restricted foetuses. Measurement of the RPT appears to be a more sensitive measure than current methods. It has the potential to identify infants with a possible reduced nephron endowment allowing for monitoring and interventions to be focused on individuals at a higher risk of developing future hypertension and chronic kidney disease.

Renal Cortical Thickness After Pyeloplasty in Pediatric Ureteropelvic Junction Obstruction

“…The return of kidney function may correlate with nephron mass, as determined by cortical thickness. 15 , 16 Renal biopsy has been used by Huang et al 17 to predict the ability of the recovery. Sclerotic glomeruli was found to be associated with severe injury of the kidney and reduction in renal function.…”

Kidney growth following preterm birth: evaluation with renal parenchyma ultrasonography

“…We have previously demonstrated that measuring only the renal parenchyma has less variance than renal volume and appears to be a more accurate method to estimate nephron number. 16,17 There are currently, to our knowledge, no studies comparing renal parenchymal growth between preterm delivered infants and undelivered normally grown fetuses who would be expected to achieve optimal renal parenchymal growth and ideal nephron endowment.…”

Themed issue on the DOHaD workshop on Fetal, Placental and Pediatric Imaging

“…Bennet et al 3 review the current state of art in the development of radiological tools for ex vivo and in vivo assessment of nephron number and glomerular size. Brennan et al investigate the use of ultrasound based fetal renal parenchymal thickness (RPT) as a novel non-invasive marker of nephron endowment 4 . The authors show that fetal RPT can be used to track the effects of fetal growth restriction on kidney development in utero.…”