Glomerular Disease and Syndromes
Glomerular disease refers to the group of disorders in which injury to the glomerulus — the filtering tuft of capillaries at the head of each nephron — disturbs the kidney's ability to retain blood cells and large proteins while excreting waste. The clinical expression of glomerular injury is conventionally organised into a small number of syndromes defined by the pattern of urinary and systemic findings, which together orient diagnosis across a wide range of immune, metabolic, and hereditary causes.
Definition
Glomerular disease is injury to the glomerular filtration apparatus that produces characteristic urinary abnormalities (proteinuria, haematuria, or both) and altered kidney function, classified clinically into syndromes and pathologically by the site and immune character of the lesion.
Scope
This area orients the reader to how glomerular injury presents and is classified. It covers the major clinical syndromes (nephritic and nephrotic), the principal immunopathologic mechanisms (immune-complex deposition, pauci-immune injury, anti-GBM disease), and representative disease categories such as ANCA-associated vasculitis and lupus nephritis. It is a reference overview that situates the child topics rather than a treatment manual; specific management belongs to current guidelines and clinicians.
Sub-topics
Core questions
- Does the presentation fit a predominantly nephritic or nephrotic pattern, or a mixed picture?
- Is the glomerular injury immune-complex mediated, pauci-immune, or related to a non-immune (e.g. podocyte) mechanism?
- Is the disease confined to the kidney or part of a systemic disorder such as lupus or a small-vessel vasculitis?
- How rapidly is kidney function changing, and does the tempo suggest a crescentic, rapidly progressive process?
Key concepts
- Glomerular filtration barrier
- Nephritic syndrome
- Nephrotic syndrome
- Proteinuria and haematuria
- Immune-complex deposition
- Pauci-immune (ANCA-associated) injury
- Crescent formation and rapidly progressive glomerulonephritis
- Glomerular versus tubulointerstitial localisation
Mechanisms
Glomerular injury arises along a few recurring pathways. Circulating or in-situ immune complexes can deposit in the mesangium or capillary wall and activate complement, producing an inflammatory, proliferative (nephritic) lesion; this underlies post-infectious glomerulonephritis, IgA nephropathy, and lupus nephritis. A pauci-immune pattern, with little immunoglobulin deposition, characterises ANCA-associated small-vessel vasculitis, in which neutrophil activation drives necrotising injury and crescents. Direct injury to the podocyte and the slit diaphragm, with or without immune deposits, increases permeability to protein and produces the nephrotic pattern, as in minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy. Where injury is severe and disrupts the capillary wall, parietal and inflammatory cells proliferate to form crescents, the histologic correlate of rapidly progressive disease (Benzing 2021; Jennette 2012; Floege 2018).
Clinical relevance
The syndromic framework is a reference tool for organising a large and otherwise unwieldy set of diseases: recognising whether a presentation is nephritic, nephrotic, or rapidly progressive narrows the differential and signals which systemic associations and confirmatory tests are typically considered. This entry describes how glomerular disease is conceptualised and classified; it does not provide diagnostic thresholds or treatment recommendations for individual patients, which rest with current guidelines and treating clinicians.
Epidemiology
Glomerular diseases are collectively an important cause of chronic kidney disease and kidney failure worldwide, though the relative frequency of specific entities varies by age, sex, geography, and biopsy practice. IgA nephropathy is among the most common primary glomerulonephritides globally, while membranous nephropathy and focal segmental glomerulosclerosis are leading causes of nephrotic syndrome in adults and minimal change disease in children (Rovin 2021; Floege 2018).
History
The understanding of glomerular disease evolved from purely clinical and light-microscopic description toward an immunopathologic classification as immunofluorescence and electron microscopy revealed distinct deposition patterns in the twentieth century. The Chapel Hill Consensus nomenclature for vasculitides and successive KDIGO guidelines have since standardised terminology and care frameworks, while molecular discoveries — such as identification of target antigens in membranous nephropathy — have begun to refine the older morphologic categories (Jennette 2012; Rovin 2021).
Key figures
- J. Charles Jennette
- Ronald J. Falk
- David J. Salant
- Thomas Benzing
Related topics
Seminal works
- jennette2012
- rovin2021
- benzing2021
Frequently asked questions
- What distinguishes a nephritic from a nephrotic presentation?
- A nephritic pattern is dominated by inflammation, with haematuria, variable proteinuria, hypertension, and reduced filtration, whereas a nephrotic pattern is dominated by heavy proteinuria with hypoalbuminaemia and oedema. Many diseases can produce overlapping or mixed pictures.
- Are glomerular diseases always confined to the kidney?
- No. Some are primary kidney diseases, but others are the renal manifestation of a systemic disorder such as systemic lupus erythematosus or an ANCA-associated small-vessel vasculitis, which is why systemic features and serologic testing are part of the evaluation.