What Is Glomerulonephritis: Symptoms, Causes, and Types Explained
Glomerulonephritis refers to a group of kidney disorders characterized by inflammation of the glomeruli—the tiny filtering units in the kidneys responsible for removing waste and excess fluids from the blood. When these structures become damaged, it often leads to noticeable changes in urine composition, most commonly hematuria (blood in the urine) and proteinuria (excess protein in the urine). These early signs are typically detected through routine urinalysis and serve as critical indicators of underlying kidney dysfunction.
Common Signs and Clinical Presentation
While abnormal urinalysis results are central to diagnosis, many patients also experience a range of systemic symptoms. Edema is frequently observed, particularly around the eyelids in the morning or in the lower extremities such as the legs and ankles. This swelling occurs due to the kidneys' reduced ability to regulate fluid balance, leading to fluid retention in tissues.
In addition, a significant number of individuals develop hypertension (high blood pressure), or find that pre-existing high blood pressure becomes more difficult to control. The connection between kidney function and blood pressure is well-established—damaged glomeruli impair the organ's ability to manage blood volume and vascular resistance, contributing to elevated readings. In clinical practice, the combination of hematuria, proteinuria, edema, and hypertension strongly suggests glomerular disease and warrants further investigation.
Understanding the Two Main Categories
Although these symptoms may appear similar across patients, the underlying causes of glomerulonephritis can vary significantly. Medical professionals classify the condition into two primary types: primary and secondary glomerulonephritis.
Primary Glomerulonephritis
This form occurs when the kidney itself is the source of the disease, with no apparent external trigger. It arises from intrinsic kidney pathology affecting the glomeruli directly. Conditions such as IgA nephropathy or membranous nephropathy fall under this category. In these cases, the immune system may mistakenly target kidney tissues, leading to inflammation and progressive damage over time.
Secondary Glomerulonephritis
In contrast, secondary glomerulonephritis develops as a complication of systemic diseases originating outside the kidneys. Autoimmune disorders are among the most common culprits. For example, lupus nephritis, a manifestation of systemic lupus erythematosus (SLE), directly impacts kidney function through widespread immune complex deposition. Similarly, Henoch-Schönlein purpura (HSP), a type of vasculitis, can lead to glomerular injury following an abnormal immune response.
Other systemic conditions like diabetes mellitus, viral infections (such as hepatitis B or C), and certain cancers can also trigger secondary forms of the disease. Identifying the root cause is essential for determining appropriate treatment strategies and improving long-term outcomes.
Why Accurate Diagnosis Matters
Given that glomerulonephritis encompasses a broad spectrum of disorders with overlapping symptoms, a precise diagnosis is crucial. Patients who receive a preliminary diagnosis should seek evaluation from a nephrology specialist. Through detailed history-taking, laboratory tests, imaging studies, and sometimes kidney biopsy, clinicians can determine whether the condition is primary or secondary.
This distinction guides therapeutic decisions—ranging from immunosuppressive therapy in autoimmune-related cases to targeted management of metabolic or inflammatory triggers. Early and accurate intervention not only helps preserve kidney function but also reduces the risk of complications such as chronic kidney disease or end-stage renal failure.