GB40 - Nephritic Syndrome: Complete ICD-11 Coding Guide

1. Introduction

Nephritic syndrome represents a nephrological emergency characterized by the sudden onset of glomerular inflammation with distinct clinical manifestations. This condition represents a pattern of kidney response to various injuries, manifesting primarily through macroscopic hematuria, oliguria, arterial hypertension, edema, and proteinuria generally at subnephrotic levels. Adequate understanding of this syndrome is fundamental for healthcare professionals, as its early recognition can prevent serious complications, including progression to acute kidney injury and the rapidly progressive form of the disease.

Nephritic syndrome affects individuals of all ages, although some specific etiologies show predilection for certain age groups. Post-streptococcal glomerulonephritis, for example, is more common in children and young adults, while other forms may predominate in older populations. The impact on public health is significant, considering that nephritic syndrome can progress to chronic kidney disease when not diagnosed and treated appropriately.

Correct coding using the GB40 code from ICD-11 is critical for multiple reasons. First, it allows precise epidemiological tracking of this condition, facilitating prevalence and incidence studies. Second, it ensures adequate reimbursement by health systems and insurers, especially considering that treatment may involve hospitalization, immunosuppressive medications, and specialized diagnostic procedures such as kidney biopsy. Third, appropriate documentation aids in communication between healthcare professionals and in continuity of care. Finally, precise coding data contribute to clinical research and the development of health policies aimed at kidney diseases.

2. Correct ICD-11 Code

Code: GB40

Description: Nephritic syndrome

Parent category: Glomerular diseases

Official definition: Nephritic syndrome is characterized by the sudden onset of glomerular disease, usually with severe hematuria (macroscopic/visible) accompanied by oliguria, elevated blood pressure, mild edema, and albuminuria or proteinuria usually in the subnephrotic range. This syndrome may be a cause of acute renal failure, in which case it is termed rapidly progressive nephritis. Nephritic syndrome has many possible causes and is associated with microscopic light renal changes, such as hypercellularity, necrosis, or thrombosis.

The ICD-11 classification positions nephritic syndrome within the broader group of glomerular diseases, recognizing that it is a pattern of clinical presentation that may have multiple underlying etiologies. Code GB40 should be used when the predominant clinical pattern is nephritic, regardless of the specific cause, although additional codes may be necessary to specify the etiology when known.

It is important to emphasize that ICD-11 recognizes nephritic syndrome as a distinct entity from other glomerular syndromes, particularly nephrotic syndrome, reflecting differences in pathophysiology, clinical presentations, and therapeutic approaches. The definition emphasizes the essential characteristics that must be present to justify the use of this code, including acute onset and the specific constellation of signs and symptoms.

3. When to Use This Code

The GB40 code should be applied in specific clinical scenarios where the nephritic pattern is clearly established. Below, we present detailed practical situations:

Scenario 1: Acute Post-Infectious Glomerulonephritis A patient presents with a history of upper respiratory tract or cutaneous infection 1-3 weeks prior, followed by sudden onset of dark urine (cola-colored), morning facial edema, arterial hypertension, and reduced urine output. Laboratory tests reveal macroscopic hematuria with red blood cell casts, proteinuria of 1.5g/24h, elevated serum creatinine, and reduced C3 complement. This is a classic example for use of code GB40, as all criteria of nephritic syndrome are present.

Scenario 2: Rapidly Progressive Nephritis Patient with rapid deterioration of renal function over days to weeks, presenting with macroscopic hematuria, severe oliguria (less than 400ml/day), difficult-to-control arterial hypertension, and edema. Renal biopsy demonstrates glomerular crescent formation in more than 50% of glomeruli. In this case, code GB40 is appropriate, as it represents the most severe form of nephritic syndrome, where acute renal insufficiency is a prominent feature.

Scenario 3: Lupus Nephritis with Nephritic Pattern Patient with established diagnosis of systemic lupus erythematosus acutely develops macroscopic hematuria, arterial hypertension, peripheral edema, and oliguria. Laboratory evaluation confirms subnephrotic proteinuria (2g/24h), active urinary sediment with dysmorphic red blood cells and red blood cell casts, and elevated creatinine. Although the underlying disease is lupus, the pattern of renal presentation is nephritic, justifying the use of GB40 as the principal code for the renal manifestation.

Scenario 4: Acute Membranoproliferative Glomerulonephritis Patient presents with an acute episode of macroscopic hematuria, accompanied by newly diagnosed arterial hypertension, lower extremity edema, and reduced urine output. Tests show proteinuria of 2.2g/24h, persistent microscopic hematuria with red blood cell casts, elevated serum creatinine, and low serum complement. Subsequent renal biopsy confirms membranoproliferative glomerulonephritis. Code GB40 is appropriate to capture the initial nephritic clinical presentation.

Scenario 5: Nephritic Syndrome in the Context of Vasculitis Patient with systemic symptoms including fever, weight loss, and respiratory manifestations develops macroscopic hematuria, arterial hypertension, edema, and oliguria. Investigation reveals positive ANCA, subnephrotic proteinuria, and deterioration of renal function. The renal presentation is clearly nephritic, even though the underlying disease is systemic vasculitis. GB40 appropriately captures the pattern of renal involvement.

Scenario 6: Idiopathic Acute Glomerulonephritis Patient without history of systemic disease or recent infection presents with abrupt onset of macroscopic hematuria, facial edema, arterial hypertension, and oliguria. Laboratory investigation confirms proteinuria of 1.8g/24h, red blood cell casts in urinary sediment, and mild elevation of creatinine. Even without defined etiology, the nephritic clinical pattern justifies the use of code GB40, which may be subsequently complemented when the cause is identified.

In all these scenarios, the essential criteria are present: acute or subacute onset, hematuria (preferably macroscopic), oliguria, arterial hypertension, edema, and subnephrotic proteinuria. The presence of this constellation of signs and symptoms is fundamental for appropriate coding with GB40.

4. When NOT to Use This Code

It is crucial to recognize situations where code GB40 is not appropriate, avoiding coding errors that may impact medical records, reimbursements, and epidemiological statistics.

Exclusion 1: Tubulointerstitial Nephritis When the patient presents with acute renal dysfunction without the typical characteristics of nephritic syndrome (absence of gross hematuria, without significant edema, absent or mild hypertension), and investigation suggests a tubulointerstitial process (for example, following use of nephrotoxic medications, ascending urinary tract infections), the appropriate code is 133532168 for unspecified tubulointerstitial nephritis. The differentiation is based on the absence of the characteristic glomerular pattern.

Exclusion 2: Pure Nephrotic Syndrome Patients with massive edema, proteinuria in the nephrotic range (>3.5g/24h), severe hypoalbuminemia and hyperlipidemia, but without gross hematuria, without significant arterial hypertension and with preserved renal function, should be coded as GB41 (Nephrotic syndrome). The fundamental distinction lies in the level of proteinuria and the absence of the acute inflammatory characteristics typical of nephritic syndrome.

Exclusion 3: Isolated Proteinuria When the predominant finding is persistent proteinuria detected on routine examinations, without gross hematuria, without edema, with normal blood pressure and preserved renal function, the correct code is GB42 (Persistent proteinuria or albuminuria). This situation represents a laboratory finding without the complete clinical picture of nephritic syndrome.

Exclusion 4: Acute Renal Failure from Other Causes Patients with acute elevation of creatinine due to prerenal causes (dehydration, hypotension), postrenal causes (urinary obstruction) or acute tubular necrosis (ischemia, toxins) should not receive code GB40, even if they present with oliguria. The absence of gross hematuria, edema and hypertension, combined with a different clinical context, indicates other diagnostic categories.

Exclusion 5: Isolated Hematuria Persistent microscopic hematuria without other components of nephritic syndrome (without oliguria, without hypertension, without edema, without significant proteinuria) does not justify the use of GB40. These situations may represent other conditions such as Berger disease in quiescent phase or benign familial hematuria.

Clear differentiation between nephritic syndrome and other renal conditions requires careful evaluation of all clinical and laboratory components. The presence of only one or two elements is not sufficient; the diagnosis of nephritic syndrome requires the complete constellation of findings.

5. Step-by-Step Coding Process

Step 1: Assess Diagnostic Criteria

The first step in appropriate coding is to confirm that the patient meets the essential criteria for nephritic syndrome. This assessment requires systematic collection of clinical and laboratory data.

Essential Clinical Assessment:

Detailed history of symptom onset (must be acute or subacute)
Characterization of urine (color, volume, presence of foam)
Evaluation of edema (location, severity, duration of progression)
Precise blood pressure measurement (compare with previous values if available)
Quantification of urine output (oliguria defined as <400ml/24h)

Necessary Diagnostic Tools:

Urinalysis type I: confirm significant macroscopic or microscopic hematuria
Urine sediment: identify red blood cell casts, dysmorphic red blood cells
24-hour proteinuria or urine protein-to-creatinine ratio
Renal function: serum creatinine, urea, estimated glomerular filtration rate
Serum complement (C3, C4): frequently reduced in various causes
Specific serologies based on suspected etiology

Diagnostic confirmation requires that at least four of the five main components be present: hematuria (preferably macroscopic), oliguria, arterial hypertension, edema, and subnephrotic proteinuria.

Step 2: Verify Specifiers

After confirming the diagnosis of nephritic syndrome, evaluate additional characteristics that may influence management and prognosis.

Severity:

Mild: preserved renal function, symptoms manageable on an outpatient basis
Moderate: moderate elevation of creatinine, hypertension controllable with medication
Severe: rapid deterioration of renal function, refractory hypertension, severe oliguria (rapidly progressive form)

Duration:

Acute: symptoms lasting less than 3 months
Subacute: symptoms lasting 3-6 months
Chronic: persistence beyond 6 months (consider diagnostic reclassification)

Special Characteristics:

Presence of acute kidney injury
Need for dialysis
Evidence of crescents on renal biopsy
Association with systemic disease

Step 3: Differentiate from Other Codes

GB41: Nephrotic Syndrome The fundamental difference lies in the pattern of proteinuria and clinical manifestations. Nephrotic syndrome presents with massive proteinuria (>3.5g/24h), significant generalized edema, severe hypoalbuminemia (<3g/dL), and hyperlipidemia. Hematuria, when present, is microscopic and discrete. Arterial hypertension is not a prominent feature. In contrast, nephritic syndrome (GB40) has subnephrotic proteinuria, striking macroscopic hematuria, significant arterial hypertension, and mild to moderate edema. The pathophysiology also differs: nephrotic due to increased glomerular permeability, nephritic due to acute glomerular inflammation.

GB42: Persistent Proteinuria or Albuminuria This code applies when proteinuria is detected on routine examinations, without the acute clinical picture of nephritic syndrome. Patients with GB42 typically do not present with macroscopic hematuria, do not have edema, maintain normal or mildly elevated blood pressure, and have stable renal function. Proteinuria is generally mild to moderate and discovered incidentally. Nephritic syndrome (GB40), on the other hand, has an acute presentation with multiple signs and symptoms occurring simultaneously.

Practical Differentiation: If massive proteinuria predominates with significant edema → GB41 If macroscopic hematuria predominates with acute hypertension → GB40 If only asymptomatic persistent proteinuria → GB42

Step 4: Required Documentation

Checklist of Mandatory Information:

[ ] Date of symptom onset
[ ] Detailed description of hematuria (macroscopic/microscopic, urine color)
[ ] Blood pressure measurements with dates
[ ] Quantification of edema (location, severity)
[ ] Daily urine volume (if oliguria present)
[ ] Quantified proteinuria results
[ ] Serum creatinine values and comparison with baseline values
[ ] Description of urine sediment (casts, dysmorphic red blood cells)
[ ] Serum complement results
[ ] Etiologic investigation performed
[ ] Renal biopsy (if performed) with histopathologic findings

Appropriate Documentation: Documentation should include a clear narrative describing the complete clinical picture, justifying the diagnosis of nephritic syndrome. Phrases such as "patient presents with nephritic syndrome characterized by..." followed by specific findings are essential. Avoid vague documentation such as "renal alterations" or "acute renal problem." Specificity ensures appropriate coding and effective communication among professionals.

6. Complete Practical Example

Clinical Case

Initial Presentation: A 28-year-old previously healthy male patient presents to the emergency department reporting that for 3 days he has noticed a change in urine color, which has become dark, "strong tea-colored." He also reports facial edema upon waking, more pronounced on the eyelids, and ankle swelling at the end of the day. He mentions that he is urinating less than usual, approximately half of his normal volume. He denies current fever but reports that about 2 weeks ago he had a sore throat that resolved spontaneously. He denies medication use or toxin exposure.

Physical Examination: Blood pressure: 160/100 mmHg (patient reports that he has always had "normal blood pressure" at previous visits) Heart rate: 88 bpm Moderate bilateral periorbital edema Lower extremity edema 2+/4+ extending to malar region Cardiopulmonary auscultation without abnormalities Abdomen without masses or pain on palpation

Initial Laboratory Evaluation:

Urinalysis: dark brown color, protein 2+, innumerable red blood cells, leukocytes 5-10/field
Urine sediment: red blood cell casts present, dysmorphic red blood cells >80%
24-hour proteinuria: 2.1 g/24h
Serum creatinine: 2.3 mg/dL (previous value from 6 months ago: 0.9 mg/dL)
Urea: 78 mg/dL
Complement C3: reduced (45 mg/dL, normal: 90-180)
Complement C4: normal
ASLO: elevated (800 IU/mL)
Serum albumin: 3.2 g/dL

Complementary Evaluation:

Renal ultrasound: kidneys of normal dimensions, without signs of obstruction
Monitored urine output: 350 ml/24h (oliguria confirmed)

Diagnostic Reasoning

Systematic analysis of the case reveals:

Acute onset: symptoms with 3 days of evolution, clearly demarcated
Macroscopic hematuria: tea-colored urine, confirmed laboratorially with innumerable red blood cells and red blood cell casts
Oliguria: urine output of 350ml/24h, patient reports subjective reduction in volume
Arterial hypertension: BP 160/100 mmHg in a previously normotensive patient
Edema: periorbital and lower extremity, of recent onset
Subnephrotic proteinuria: 2.1g/24h (below the nephrotic threshold of 3.5g/24h)
Acute kidney injury: creatinine elevated from 0.9 to 2.3 mg/dL

The complete constellation of findings clearly configures a nephritic syndrome. The context of upper respiratory tract infection 2 weeks ago, reduced complement C3, and elevated ASLO suggest post-streptococcal glomerulonephritis as the most likely etiology.

Coding Step by Step

Criteria Analysis: ✓ Macroscopic hematuria present ✓ Documented oliguria (<400ml/24h) ✓ Confirmed arterial hypertension ✓ Edema present (facial and lower extremities) ✓ Subnephrotic proteinuria (2.1g/24h) ✓ Acute kidney injury (creatinine elevation) ✓ Active urine sediment (red blood cell casts, dysmorphic red blood cells)

Code Selected: GB40 - Nephritic Syndrome

Complete Justification: Code GB40 is the most appropriate because the patient presents all the defining elements of nephritic syndrome according to ICD-11 classification. The sudden onset of symptoms, macroscopic hematuria as a prominent manifestation, documented oliguria, new-onset arterial hypertension, mild to moderate edema, and subnephrotic range proteinuria perfectly configure the nephritic pattern. The presence of acute kidney injury is compatible with the diagnosis and does not exclude the use of this code, as ICD-11's own definition recognizes that nephritic syndrome can cause AKI.

The differentiation from GB41 (nephrotic syndrome) is clear due to subnephrotic proteinuria and the prominence of macroscopic hematuria and hypertension. The differentiation from GB42 (persistent proteinuria) is evident from the acute and symptomatic presentation, not being an isolated laboratory finding.

Complementary Codes: Although the primary code is GB40, additional codes may be considered to specify:

The probable etiology (post-streptococcal glomerulonephritis)
The presence of acute kidney injury
Secondary arterial hypertension

This multiple coding provides more complete information about the clinical presentation, but GB40 remains as the primary code capturing the pattern of renal presentation.

7. Related Codes and Differentiation

Within the Same Category

GB41: Nephrotic Syndrome

When to use GB41 vs. GB40: The code GB41 should be used when the predominant clinical pattern is characterized by massive proteinuria (>3.5g/24h in adults), severe hypoalbuminemia (<3g/dL), significant generalized edema, and hyperlipidemia. Patients with nephrotic syndrome typically present with marked peripheral edema that may progress to anasarca, with ascites and pleural effusion in severe cases. Hematuria, when present, is microscopic and subtle. Blood pressure may be normal or mildly elevated, but there is no significant acute hypertension as seen in nephritic syndrome.

Main Difference: The fundamental distinction lies in pathophysiology and clinical presentation. Nephrotic syndrome results from increased glomerular permeability to protein, leading to massive albumin loss. Nephritic syndrome (GB40) results from acute glomerular inflammation with cellular proliferation, causing prominent hematuria and hypertension. In practice: if massive edema with intense proteinuria predominates → GB41; if macroscopic hematuria with acute hypertension predominates → GB40.

GB42: Persistent Proteinuria or Albuminuria

When to use GB42 vs. GB40: The code GB42 applies to situations where proteinuria or albuminuria is detected on a persistent basis (confirmed on multiple occasions), but without the acute and symptomatic clinical picture of nephritic syndrome. These patients are generally asymptomatic, with proteinuria discovered on routine examinations. They do not present with macroscopic hematuria, have no edema, maintain normal or controlled blood pressure, and present with stable renal function or slow deterioration. Proteinuria is generally mild to moderate (<3g/24h).

Main Difference: Nephritic syndrome (GB40) is an acute and symptomatic presentation with multiple simultaneous manifestations, while persistent proteinuria (GB42) is a chronic laboratory finding, usually asymptomatic. The temporal context is crucial: GB40 for acute presentations with days to weeks of evolution; GB42 for persistent findings over months without acute manifestations.

Differential Diagnoses

Conditions That May Be Confused:

Acute Tubulointerstitial Nephritis: May present with acute renal insufficiency and urinary abnormalities, but typically without macroscopic hematuria. The history frequently includes use of nephrotoxic medications, infections, or systemic diseases. Urinary sediment shows leukocyturia and leukocyte casts, not red blood cell casts. Arterial hypertension is not a prominent characteristic.

Pre-Renal Acute Kidney Injury: May present with oliguria and elevated creatinine, but without macroscopic hematuria, without edema, and generally without hypertension. The clinical context of dehydration, hypotension, or low cardiac output is evident. Urinary indices (fractional excretion of sodium, urinary density) aid in differentiation.

Urinary Obstruction: May cause acute renal insufficiency with oliguria, but hematuria, when present, is not typically macroscopic and there is no complete nephritic pattern. Renal ultrasound demonstrates hydronephrosis, which is absent in nephritic syndrome.

How to Distinguish Clearly: The key to differentiation lies in complete evaluation of the clinical picture. Nephritic syndrome presents the characteristic triad of macroscopic hematuria + arterial hypertension + edema, associated with oliguria and subnephrotic proteinuria. The simultaneous presence of these elements, with acute onset, is distinctive. Urinary sediment with red blood cell casts and dysmorphic red blood cells confirms glomerular origin. When in doubt, renal biopsy may be necessary, revealing patterns of cellular proliferation, necrosis, or glomerular crescents in nephritic syndrome.

8. Differences with ICD-10

Equivalent ICD-10 Code: In ICD-10, nephritic syndrome is coded in category N00-N08, with N00 representing "Acute nephritic syndrome" and subdivisions based on histopathological findings when known (N00.0 to N00.9).

Main Changes in ICD-11:

The transition from ICD-10 to ICD-11 brought important modifications in the coding of glomerular diseases. In ICD-10, there was greater emphasis on histopathological classification, with multiple codes based on biopsy findings (minimal lesions, mesangial proliferation, membranoproliferative, etc.). ICD-11, represented by code GB40, adopts a more clinical approach, focusing on the pattern of presentation (nephritic syndrome) regardless of specific histology.

ICD-11 simplifies coding by recognizing that many cases of nephritic syndrome do not have renal biopsy performed, especially when the etiology is evident (such as in post-streptococcal glomerulonephritis) or when biopsy is contraindicated. Code GB40 can be used even without histological confirmation, as long as the clinical pattern is present.

Another significant change is better differentiation between acute and chronic patterns. ICD-11 allows more precise coding of disease phase and severity, including the rapidly progressive form within the same category.

Practical Impact of These Changes:

For healthcare professionals, ICD-11 facilitates coding by allowing use based on clinical criteria, without mandatory histological specification. This is particularly useful in emergency services and in settings with limited access to renal biopsy.

For health systems and managers, the change allows better epidemiological tracking of nephritic syndrome as a clinical entity, independent of histological variations. Studies of prevalence and incidence become more comparable between different regions and services.

For researchers, ICD-11 maintains the possibility of additional specification when histological information is available, through complementary codes, allowing detailed analyses when necessary.

The transition requires updating computerized systems and training coding teams, but the result is a more intuitive and clinically relevant system. Professionals should be attentive during the transition period, when both systems may coexist in different administrative contexts.

9. Frequently Asked Questions

1. How is nephritic syndrome diagnosed?

The diagnosis of nephritic syndrome is essentially clinical, based on the simultaneous presence of hematuria (preferably macroscopic), oliguria, arterial hypertension, edema, and subnephrotic proteinuria. Initial evaluation includes detailed clinical history investigating recent infections, medication use, and systemic diseases. Physical examination should document blood pressure and the presence and extent of edema. Essential laboratory tests include urinalysis, urinary sediment (looking for red blood cell casts and dysmorphic red blood cells), 24-hour quantified proteinuria, renal function (creatinine and urea), serum complement, and specific serologies according to suspected etiology. Renal biopsy is reserved for atypical cases, with unfavorable evolution, or when histological definition is needed to guide immunosuppressive treatment.

2. Is nephritic syndrome treatment available in public health systems?

Yes, nephritic syndrome treatment is generally available in public health systems, although the complexity of access may vary. Initial management includes supportive measures such as salt and fluid restriction, blood pressure control with antihypertensives (frequently available in basic formularies), and diuretics for edema control. Severe cases may require hospitalization for monitoring and intensive treatment. When immunosuppression is indicated (rapidly progressive forms or those associated with autoimmune diseases), medications such as corticosteroids and cyclophosphamide should be accessible, although they may require special approvals. Dialysis, necessary in cases of severe acute renal failure, should be available in referral centers.

3. How long does nephritic syndrome treatment last?

The duration of treatment varies significantly depending on etiology and severity. In post-streptococcal glomerulonephritis, a common form that is generally self-limited, supportive treatment may last 2-4 weeks, with complete recovery in most cases. Forms associated with autoimmune diseases or vasculitis may require immunosuppressive treatment for 6-12 months or longer. Rapidly progressive nephritis requires immediate aggressive treatment, frequently with corticosteroid pulse therapy and cyclophosphamide for 3-6 months, followed by maintenance therapy. Nephrological follow-up may be necessary for years, even after resolution of the acute episode, to monitor renal function and detect recurrences early.

4. Can this code be used in medical certificates and official documents?

Yes, code GB40 can and should be used in medical certificates, hospital reports, reimbursement documents, and other official records when the diagnosis of nephritic syndrome is established. Proper coding is important for medical-legal documentation, communication between healthcare professionals, insurance processing and benefits, and for statistical purposes. In certificates, one may use the term "nephritic syndrome" or simply "acute kidney disease" if there is concern about privacy, but code GB40 should be present in the complete medical documentation. For work absences, the severity and need for rest should be individualized, considering that mild cases may allow limited activities, while severe cases require complete absence from work.

5. Can nephritic syndrome progress to chronic kidney disease?

Yes, although many cases of nephritic syndrome, especially post-streptococcal glomerulonephritis, resolve completely without sequelae, there is a risk of progression to chronic kidney disease. Factors that increase this risk include: presentation as rapidly progressive nephritis, presence of extensive glomerular crescents on biopsy, incomplete recovery of renal function after the acute episode, persistent proteinuria, uncontrolled arterial hypertension, and recurrent episodes. Studies indicate that approximately 10-20% of patients with nephritic syndrome may develop some degree of chronic renal dysfunction. Therefore, long-term nephrological follow-up is recommended, even in patients who apparently completely recovered from the acute episode.

6. Is renal biopsy necessary to confirm the diagnosis?

Renal biopsy is not mandatory in all cases of nephritic syndrome. In situations where the clinical presentation is typical and the etiology is evident (such as post-streptococcal glomerulonephritis in a child with classic history), the diagnosis can be established clinically. Biopsy is indicated when: the diagnosis is uncertain, there is atypical or unfavorable evolution, rapidly progressive forms are suspected that require aggressive immunosuppressive treatment, histological definition is needed to guide specific therapy, or when the patient does not respond to initial treatment. The decision to perform biopsy should consider risks and benefits, and is generally performed by nephrologists in specialized centers.

7. Do children and adults present nephritic syndrome in the same way?

Although diagnostic criteria are similar, there are important differences between children and adults. In children, post-streptococcal glomerulonephritis is the most common cause and generally has an excellent prognosis with complete recovery. Facial edema is often more prominent in children. In adults, there is greater diversity of etiologies, including vasculitis, autoimmune diseases, and idiopathic forms, with more variable prognosis. Adults have a higher risk of progression to chronic kidney disease. Reference values for proteinuria also differ (in children, >40mg/m²/hour is considered significant). The threshold for renal biopsy tends to be lower in adults due to more diverse and potentially severe etiologies.

8. Do patients with nephritic syndrome need a special diet?

Yes, dietary modifications are an important part of nephritic syndrome management. Sodium restriction (generally 2-3g/day) is fundamental for edema and arterial hypertension control. Fluid restriction may be necessary in cases with severe oliguria, typically limiting fluids to 500ml above the previous day's urine output. Moderate protein restriction (0.8-1.0g/kg/day) may be recommended to reduce kidney workload, although it should not be excessive to avoid malnutrition. Potassium may need restriction if hyperkalemia is present. These guidelines should be individualized with specialized nutritional follow-up, and may be gradually liberalized as clinical and laboratory improvement occurs. After resolution of the acute episode, diet can return to normal, although maintenance of healthy habits is recommended.

Conclusion

The GB40 code of ICD-11 for nephritic syndrome represents an essential tool for accurate documentation of an acute and potentially severe nephrological condition. Adequate understanding of diagnostic criteria, appropriate situations for use of this code, and necessary differentiation from other glomerular conditions is fundamental for healthcare professionals involved in the diagnosis, treatment, and coding of kidney diseases.

Nephritic syndrome, characterized by its acute presentation with macroscopic hematuria, oliguria, arterial hypertension, edema, and subnephrotic proteinuria, requires early recognition and appropriate management to prevent complications such as chronic kidney failure. Correct coding with GB40 not only facilitates communication between professionals and administrative processing, but also contributes to epidemiological surveillance and clinical research that can improve patient outcomes globally.

This guide provides the necessary tools for practical application of the GB40 code, from initial assessment to complete documentation, enabling healthcare professionals to appropriately utilize the ICD-11 classification in the context of glomerular diseases.

External References

This article was prepared based on reliable scientific sources:

References verified on 2026-02-04

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