Glomerulonephritis – Symptoms and Diet

Glomerulonephritis (GN) represents a diverse spectrum of renal disorders unified by primary inflammatory damage to the glomerular apparatus, driven predominantly by immunological dysfunction. While the inflammatory process may initially confine itself to the glomeruli, its downstream effects frequently extend to secondary alterations within renal tubules, the interstitial compartment, and vascular structures, primarily due to impaired filtration and pathological proteinuria. The etiology remains elusive in a substantial proportion of cases, though current evidence implicates aberrant immune responses—either through the deposition of immune complexes within glomerular capillaries or direct autoantibody-mediated injury. Analogous to other immune-mediated conditions, GN may manifest as recurrent exacerbations, periods of remission, or a steadily progressive chronic course. Acute presentations often arise as allergic-inflammatory responses to persistent or recurrent bacterial infections within the host, whereas chronic glomerulonephritis occasionally emerges as a sequela of untreated acute disease but more commonly develops *de novo*. The onset is frequently insidious, sometimes remaining clinically silent for years, with gradual glomerular fibrosis, sclerosis, and replacement by fibrous tissue ultimately culminating in end-stage renal failure and uremia. Classification distinguishes between *primary GN*—where pathology is restricted to the glomeruli and clinical/laboratory abnormalities stem directly from their malfunction (e. g., postinfectious GN)—and *secondary GN*, wherein glomerular injury arises as a complication of systemic diseases such as diabetes mellitus, systemic lupus erythematosus, or amyloidosis.

Acute glomerulonephritis presents with a constellation of concerning clinical features, including: severe, localized pain in the lumbar region of the spine, a marked reduction in daily urine output (oliguria), edema predominantly affecting the upper body—particularly the face and periorbital areas—as well as microscopic hematuria (defined by the presence of more than three erythrocytes per high-power microscopic field). Additional findings include moderate proteinuria (exceeding 2. 5 grams per day, with values above 3. 5 g/day indicative of full-blown nephrotic syndrome), generalized physical weakness, anorexia, excessive daytime somnolence, elevated systemic arterial pressure, dark—often brownish-red—urine discoloration, febrile episodes, and potential convulsive seizures. In chronic glomerulonephritis, the clinical picture typically involves: frothy urine (reflecting significant protein content), persistent hematuria, generalized soft-tissue edema, ascites, diminished physical endurance, chronic fatigue, anemia, recurrent headaches, and sustained arterial hypertension. Essential diagnostic evaluations comprise: comprehensive urinalysis (assessing proteinuria and hematuria), serum biochemical profiling (focusing on renal function markers such as creatinine and blood urea nitrogen, alongside electrolyte balance—sodium and potassium), abdominal ultrasonography for structural assessment, and—when clinically indicated—renal biopsy to facilitate histopathologic examination of glomerular alterations.

Dietary intervention and nutritional management in glomerulonephritis must be strictly personalized based on renal functional capacity and glomerular filtration rate. Dietary adjustments depend on regular monitoring of core biochemical parameters: serum urea concentration (normal range: 2. 5–6. 7 mmol/L or 15–40 mg/dL), serum creatinine concentration (normal range: 60–120 µmol/L or 0. 7–1. 35 mg/dL), and daily fluid balance (precise matching of fluid intake to urinary output and insensible losses). The foundational principles of a renal-sparing diet include: controlled dietary protein restriction to limit the accumulation of nitrogenous waste products (urea and creatinine)—typically 0. 6 to 0. 8 grams per kilogram of body weight per day in adults, with at least 50% derived from high biological value sources; restriction of foods high in phosphorus, potassium, and purines (such as cocoa, dried apricots, tomato paste, sunflower seeds, almonds, organ meats, and oily fish); strict limitation of dietary sodium to mitigate arterial hypertension and edema; tailored fluid intake calculated as the previous day’s urine output plus approximately 500 mL for insensible perspiration; adequate caloric density (typically 35 kcal/kg/day) primarily from complex carbohydrates and easily digestible vegetable oils (rapeseed, flaxseed) to prevent endogenous protein catabolism; and inclusion of urine-alkalizing vegetables while carefully monitoring potassium load. Glomerulonephritis is a serious medical condition requiring close nephrological and dietetic supervision.