N00-N08

Glomerular diseases

Glomerular diseases (N00-N08) represent a complex spectrum of renal pathologies characterized by damage to the glomeruli, the functional filtration units of the kidney. These conditions are categorized based on their clinical presentation (nephritic versus nephrotic patterns), histopathological findings, and clinical course (acute, rapidly progressive, or chronic). The pathophysiological basis usually involves immunological mechanisms, such as immune complex deposition or antibody-mediated injury to the glomerular basement membrane or podocytes. Clinical manifestations typically result from a decrease in glomerular filtration rate (GFR) and a loss of selective permeability, leading to the leakage of proteins and blood cells into the urine. If left untreated or if they become chronic, these diseases can progress to end-stage renal disease (ESRD), requiring renal replacement therapy.

Clinical Symptoms

  • Hematuria (gross or microscopic)
  • Proteinuria (often manifesting as foamy or bubbly urine)
  • Peripheral edema (swelling in the ankles, feet, or legs)
  • Periorbital edema (swelling around the eyes, especially in the morning)
  • Hypertension (new-onset or worsening control)
  • Oliguria (reduced urine output)
  • Uremic symptoms (fatigue, nausea, loss of appetite, pruritus)
  • Ascites or pleural effusions in severe nephrotic cases
  • General malaise and weakness
  • Flank pain (less common, seen in acute cases)

Common Causes

  • Primary glomerulopathies (e.g., Minimal Change Disease, IgA Nephropathy, FSGS)
  • Post-infectious glomerulonephritis (e.g., Post-streptococcal GN, Hepatitis B or C, HIV)
  • Autoimmune disorders (e.g., Systemic Lupus Erythematosus, ANCA-associated vasculitis)
  • Metabolic diseases (e.g., Diabetic Nephropathy, Amyloidosis)
  • Genetic mutations affecting podocyte proteins or collagen (e.g., Alport syndrome)
  • Drug-induced injury (e.g., NSAIDs, lithium, gold salts)
  • Malignancy-associated glomerular injury
  • Preeclampsia-related glomerular damage

Documentation & Coding Tips

Differentiate between Nephritic and Nephrotic Syndrome using specific protein and hematuria thresholds.

Example: Assessment: Patient presents with sudden onset of gross hematuria, hypertension (155/92), and mild peripheral edema. Labs reveal proteinuria of 1.8 g/24h and presence of RBC casts in urine sediment. This clinical picture is consistent with Acute Nephritic Syndrome (N00.9). No history of previous renal disease. Plan: Renal biopsy to determine specific morphological lesion and initiate pulse steroid therapy.

Billing Focus: N00.9 supports the clinical manifestations of acute nephritic syndrome without a confirmed biopsy lesion at this encounter.

Specify the morphological lesion as identified by renal biopsy to move beyond unspecified codes.

Example: Biopsy Results: Light microscopy shows diffuse effacement of podocyte foot processes. Diagnosis: Nephrotic syndrome with minimal change disease (N04.0). Patient currently in CKD Stage 2 (N18.2). Management: Continuing Prednisone 60mg daily. Billing: Specificity provided for minimal change lesion.

Billing Focus: N04.0 provides maximal specificity for the lesion type as required by 2026 ICD-10 guidelines.

Explicitly link glomerular disorders to underlying systemic diseases such as Lupus or Diabetes.

Example: Assessment: 45-year-old female with known Systemic Lupus Erythematosus (SLE). Recent increase in serum creatinine to 1.8 and proteinuria of 3.5 g/day. Clinical diagnosis of Lupus Nephritis, Class IV. ICD-10: Glomerular disorders in systemic lupus erythematosus (M32.14) and Glomerular disorders in diseases classified elsewhere (N08). Current CKD Stage 3a (N18.31).

Billing Focus: Dual coding is required; the systemic disease (M32.14) is sequenced first, followed by the renal manifestation code (N08).

Document the acuity and chronicity of glomerular symptoms to distinguish between N00 and N03.

Example: Subjective: Patient reports persistent brown-colored urine and morning facial puffiness for the last 6 months. Objective: Stable hypertension and persistent sub-nephrotic proteinuria. Assessment: Chronic nephritic syndrome with diffuse membranous glomerulonephritis (N03.2). Chronic kidney disease, stage 4 (N18.4) noted. Plan: Adjust lisinopril and monitor GFR monthly.

Billing Focus: Chronicity (N03.x) is supported by the 6-month symptom duration and biopsy findings.

Clearly state the presence of Isolated Proteinuria when nephrotic or nephritic syndromes are not fully met.

Example: Screening: Routine physical for 18-year-old male. Urinalysis shows 2+ protein but no hematuria, no hypertension, and normal albumin. Diagnosis: Isolated proteinuria with specified morphological lesion, minor glomerular abnormality (N06.0). Follow-up scheduled in 3 months for repeat quantification.

Billing Focus: N06 codes are used for cases where proteinuria is the primary finding without the full clinical syndrome of nephrosis.

Relevant CPT Codes

Related Diagnoses

Hierarchy