Podocyturia in Fabry disease: A 10-year follow-up

Clin Kidney J. 2021 Sep 16;15(2):269-277. doi: 10.1093/ckj/sfab172.

PMID: 35145641

Bojan Vujkovac, Irena Srebotnik Kirbiš, Tajda Keber

Highlights: Podocyturia is considered as a non-invasive early marker of kidney injury in Fabry disease, but it should be kept in mind that podocyturia is a discontinuous event with wide variability.

Abstract

Background: Fabry disease is an X-linked sphingolipid metabolic disorder that causes chronic proteinuric nephropathy. Podocytes are one of the most impacted renal cells, and they play a crucial role in the progression and development of kidney disease. Detached podocytes in urine (podocyturia) are thought to be a non-invasive early indicator of kidney injury, although the dynamics of podocyte loss are unknown.

Methods: Podocyturia and other renal clinical data were assessed in 39 patients with FD in this 10-year follow-up research. Using immunocytochemical detection of podocalyxin, podocyturia was examined in 566 fresh urine samples from 13 male and 26 female FD patients from 2009 to 2019.

Results: Podocyturia (number of podocytes per 100 mL of urine) was found in 311/566 (54.9%) of the samples, with males having more podocytes per gram of creatinine (Cr) in urine (68.9 ± 21.9% versus 50.6 ± 25.9%; P = 0.035) and higher values (364 ± 286 versus 182 ± 180 number of podocytes per gram of Cr in urine; P = 0.020). Each patient had an average of 14.5 evaluated samples (range 3-40), with a frequency of samples with podocyturia ranging from 0% to 100%. (median 57%). Podocyturia was found in 42.9% of children under the age of 20 and 89.5% of patients with normoalbuminuria. Podocyturia was found to be associated with albuminuria (urine albumin:Cr ratio) (r = 0.20, P < 0.001), and patients with a lower estimated glomerular filtration rate had a greater incidence and value of podocyturia.

Conclusions: Podocyturia is an early clinical event in the development of nephropathy, according to our findings. Furthermore, we discovered that podocyturia is a discontinuous event with wide variability.

Keywords: Fabry, Fabry disease, albuminuria, biomarkers, immunocytochemistry, podocalyxin, podocyturia, proteinuria, renal function