- The renal tubulointerstitium is an often underappreciated compartment of the kidney but of great importance in acute kidney disease and CKD. As early as the 1970s, Bohle and colleagues1 recognized that kidney function did not correlate well with the severity of glomerular disease but rather with the relative interstitial volume. We now know that the microenvironment encompassing the tubulointerstitium is composed of tubular epithelial cells, interstitial cells, peritubular capillary endothelium, pericytes, and extracellular matrix, which have complex structural and functional relationships.
- Focal and segmental glomerulosclerosis (FSGS) has been increasing in incidence over several decades. It is the underlying cause of nephrotic syndrome in 40% of adults and 20% of children and is the most common primary glomerular lesion resulting in end-stage kidney disease in the United States.1 FSGS is not a single disease but a morphologic pattern of injury that develops from a wide range of etiologies. The terminology refers to the pattern of scarring in the glomerulus (glomerulosclerosis), which is focal (involving only a portion of the glomerular population) and segmental (affecting only a portion of the glomerular tuft).
- Glomerular disease has been estimated to occur in approximately 18 per 100,000 people, although the exact incidence is difficult to determine.1 Factors such as recognition of urinary abnormalities, renal biopsy practice, infections, health resources, socioeconomic conditions, and environmental factors significantly affect the incidence of glomerular disorders, which actually may be higher than reported. In addition, systemic and vascular diseases such as diabetes and hypertension substantially increase the incidence of nephropathies associated with CKD.