Nephritic Syndrome, Emergency Medicine

Basics

Description

Acute glomerulonephritis (AGN) is acute inflammatory damage to glomerulus, associated with:
- Abrupt onset of hematuria with or without RBC casts
- Acute renal failure manifested by edema, hypertension, azotemia, decline in urine output
- Variable proteinuria
- Active urine sediment (RBC casts)
Exact mechanism of AGN unclear:
- Combination of autoimmune reactivity to specific antigens at renal glomeruli
- Characterized by crescent formation secondary to nonspecific injury at the glomerular wall

Etiology

Poststreptococcal glomerulonephritis (PSGN):
- A postinfectious cause of acute nephritic syndrome, resulting from group A ²-hemolytic streptococci
- Considered a nonsuppurative complication (antibiotic treatment does not prevent this complication)
- Occurs when immune complexes create hump-shaped subepithelial deposits in renal glomeruli
- Most commonly affects patients between ages 3 and 15 yr but can occur at any age
- Incidence of nephritis is 5 " 10% after pharyngitis and 25% after skin infections.
- Consider PSGN in the setting of new-onset proteinuria, RBC casts, edema, and any recent infection.
- Latent period between infection and onset of nephritis helps differentiate between PSGN and IgA nephropathy:
  - 1 " 3 wk in pharyngeal infection
  - 2 " 4 wk in cutaneous infection
- Renal biopsy is usually not necessary for diagnosis.
- Low complement (C3) for 6 " 8 wk
- Can progress to severe renal failure if underlying infection goes untreated
- Prognosis:
  - Excellent; >95% recover spontaneously with normalization of renal function within 6 " 8 wk, even with dialysis.
  - Hematuria usually resolves in 3 " 6 mo.
  - Transient nephrotic phase in 20% of patients during resolution of illness
  - End-stage renal disease occurs <5%
  - Rapidly progressive glomerulonephritis (RPGN) is rare, occurring in <1% cases.
  - Most cases resolve spontaneously with no long-term sequelae.
Other infectious sources of glomerulonephritis (GN):
- Sepsis, pneumonia, endocarditis, viruses, HIV
- Pulmonary, intra-abdominal, or cutaneous infections
- Syphilis, leprosy, schistosomiasis, and malaria
- Goal: Treat underlying infection.
Hepatitis virus " related glomerular disease:
- Can present with either nephritic or nephrotic symptoms
- Causes membranoproliferative GN
- Complements remain low indefinitely (compared to PSGN)
Noninfectious causes of GN (due to immune complex formation):
- Systematic lupus erythematosus, Henoch " Sch Άnlein purpura, vasculitis, Wegener granulomatosis
- Goodpasture syndrome
IgA nephropathy (IgA-N)
- Most common cause of AGN (>25%) worldwide
- Antibody " antigen causes immune complex deposition of IgA and C3
- Complement levels are usually normal.
- IgA-N has different presentations:
  - Gross hematuria following upper respiratory infection (URI)
  - Microscopic hematuria with proteinuria
  - Hematuria during viral illness or after exercise
  - Prognosis is related to serum creatinine, BP, and proteinuria.
  - 50% of patients with proteinuria may develop progressive renal disease.
  - ACE inhibitors or angiotensin-receptor blockers (ARBs) may help
RPGN:
- Certain patients with AGN may progress rapidly to renal failure.
- Hallmarks are crescents on renal biopsy.
Hereditary nephritis
- Alport syndrome

Diagnosis

Signs and Symptoms

Hematuria:
- Abrupt onset gross hematuria in 30 " 40% (coffee- or cola-colored urine)
Edema:
- Periorbital edema
- Generalized edema more common in infants and children
Infectious source or recent infection: Upper respiratory tract or skin common, e.g., PSGN
Symptoms of congestive heart failure:
- 40% occurrence in patients >60 yr
- Rare in children
Arthritis, arthralgias, and various skin rashes: PSGN, systemic disease
Nonspecific manifestations:
- Malaise
- Weakness
- Anorexia
- Nausea/vomiting

History

Recent URI or skin or other infection
Change in urine color

Physical Exam

Hypertension
Edema

Essential Workup

Urinalysis with sediment evaluation to detect:

RBCs, proteinuria, and RBC casts
RBC casts are diagnostic of an active glomerular inflammation.

Diagnosis Tests & Interpretation

Lab

CBC:
- Anemia (seen in more chronic cases of GN or other systemic disease)
- Acute leukocytosis (may suggest infectious process)
Basic metabolic panel:
- Assess baseline renal function
- Check for electrolyte abnormalities
- GFR will be normal or nearly normal
Urinalysis:
- RBCs +/ ’ casts, protein
Serum albumin
Cultures (throat, skin, urine, blood):
- As clinically suspected for infectious source
- Streptozyme
Serum complement level (C3): Decreased in infectious endocarditis, shunt nephritis, and PSGN
Streptococcal antibodies:
- Antistreptolysin (ASO), antistreptokinase (ASK), antideoxyribonuclease B (ADNase B), antinicotinyl adenine dinucleotidase (ANADase), and antihyaluronidase (AH)
- ASO more reactive in pharyngeal infections
- ADNase B, ANADase, and AH more reactive in cutaneous infections
- ASK elevated in recent hemolytic Streptococcus infections
- Titers do not correlate with prognosis of disease
Urine osmolality, sodium, creatinine
24-hr urine collection:
- Proteinuria initially present in 5% of children, 20% of adults with PSGN

Imaging

Renal ultrasound: Kidney size abnormality
Chest radiograph: Cardiomegaly, pulmonary edema, infection

Diagnostic Procedures/Surgery
Renal biopsy:

Generally not done for PSGN, as symptoms typically resolve after a brief illness
Recommended if atypical features of PSGN, persistently abnormal complement levels, persistent hypertension, and proteinuria >3 g/d
Facilitates diagnosis for other causes of nephritis

Differential Diagnosis

(See "Glomerulonephritis " for further information on types of GN)
Renal:
- Primary glomerular disease
Systemic:
- Goodpasture syndrome
- Vasculitis
- Henoch " Sch Άnlein purpura
Other (rare):
- Hemolytic-uremic syndrome
- Thrombotic thrombocytopenic purpura
- Acute hypersensitivity interstitial nephritis
- Serum sickness

Treatment

Pre-Hospital

Support ABCs

Initial Stabilization/Therapy

ABCs

Ed Treatment/Procedures

Antibiotics for streptococcal infection:
- Penicillin (erythromycin, if penicillin allergic)
Restrict salt and fluid intake
Administer loop diuretics (furosemide)
Restore urine flow in oliguric patients:
- Mannitol
Treat pulmonary edema:
- Oxygen
- Morphine
- Loop diuretics
Stabilize BP to decrease proteinuria, retard progression of GN:
- ACEIs, ARBs
- Hypertensive emergency: Nitroprusside or other titratable antihypertensive medication
Hemodialysis for:
- Severe hyperkalemia
- Fluid overload
- Uremia
- Severe acidosis
- Correct electrolyte abnormalities

Medication

Erythromycin: 250 " 500 mg (peds: 30 " 50 mg/kg/d) PO q6h for 7 " 10 days
Furosemide: 20 " 80 mg (peds: 1 " 6 mg/kg) PO daily/BID
Lisinopril (ACEI): 10 " 40 mg (peds: >6 yr: 0.07 mg/kg) PO daily
Losartan (ARB): 25 " 100 mg (peds: >6 yr: 0.7 mg/kg) PO daily
Mannitol: 12.5 " 100 g (peds: 0.25 " 0.5 g/kg) IV:
- May use single or repeat dosing; consider test dosing 1st.
Morphine sulfate: 0.1 mg/kg/dose IV q4h
Nitroprusside: 0.3 " 4 Όg/kg/min IV
- Titrate to goal mean arterial pressure for hypertensive emergency.
Penicillin:
- Benzathine penicillin: 1.2 million U (peds: 0.3 " 0.9 million U, based on weight) IM as single dose
- Penicillin VK: 250 " 500 mg (peds: <12 yr 25 " 50 mg/kg/d) PO q6 " 8h for 10 days
Other agents, including fish oil ( -3 fatty acids for anti-inflammatory effects) and immunosuppressive agents (glucocorticoids, cyclophosphamide), may be used in consultation with specialists.

Follow-Up

Disposition

Admission Criteria

Evidence of infectious cause for GN
Oliguria, anuria
Uremia
Elevated creatinine
Edema
Electrolyte abnormalities
Severe hypertension
CHF

Discharge Criteria
Mild cases of clinical nephritis in healthy patients with:

No comorbid illness
Strict supervision/monitoring of symptoms, diet, urine output, and medication
Close follow-up with PMD and nephrology referral

Issues for Referral
Nephrology:

Within 2 " 3 days

Follow-Up Recommendations

Adherence to antibiotic and antihypertensive therapy, as indicated
Restrict salt and fluid intake.

Pearls and Pitfalls

Diagnosis is confirmed by biopsy showing characteristic crescent formation within renal glomeruli.
Must obtain thorough history of ongoing or recent infections as possible etiology of nephritis
IgA nephropathy is most common cause of nephritis.
Patients require aggressive management of BP and volume status.

Additional Reading

Ikee R, Kobayashi S, Saigusa T, et al. Impact of hypertension and hypertension-related vascular lesions in IgA nephropathy. Hypertens Res. 2006;29(1):15 " 22.
Kanjanabuch T, Kittikowit W, Eiam-Ong S. An update on acute postinfectious glomerulonephritis worldwide. Nat Rev Nephrol. 2009;5:259 " 269.
Kunz R, Friedrich C, Wolbers M, et al. Meta-analysis: Effect of monotherapy and combination therapy with inhibitors of the renin angiotensin system on proteinuria in renal disease. Ann Intern Med. 2008;148(1):30 " 48.

Codes

ICD9

580.0 Acute glomerulonephritis with lesion of proliferative glomerulonephritis
580.9 Acute glomerulonephritis with unspecified pathological lesion in kidney
583.2 Nephritis and nephropathy, not specified as acute or chronic, with lesion of membranoproliferative glomerulonephritis
583.4 Nephritis and nephropathy, not specified as acute or chronic, with lesion of rapidly progressive glomerulonephritis

ICD10

N00.9 Acute nephritic syndrome with unsp morphologic changes
N01.9 Rapidly progr nephritic syndrome w unsp morphologic changes
N05.9 Unsp nephritic syndrome with unspecified morphologic changes
N05.1 Unsp neph syndrome w focal and segmental glomerular lesions
N05.0 Unsp nephritic syndrome with minor glomerular abnormality
N05.2 Unsp nephritic syndrome w diffuse membranous glomrlneph
N05.3 Unsp neph syndrome w diffuse mesangial prolif glomrlneph
N05.4 Unsp neph syndrome w diffuse endocaplry prolif glomrlneph
N05.5 Unsp nephritic syndrome w diffuse mesangiocap glomrlneph
N05.6 Unspecified nephritic syndrome with dense deposit disease
N05.7 Unsp nephritic syndrome w diffuse crescentic glomrlneph
N05.8 Unsp nephritic syndrome with other morphologic changes
N05 Unspecified nephritic syndrome

SNOMED

7724006 Nephritic syndrome (disorder)
19351000 Acute glomerulonephritis (disorder)
236392004 Rapidly progressive glomerulonephritis (disorder)
80321008 Mesangiocapillary glomerulonephritis (disorder)
68544003 Acute post-streptococcal glomerulonephritis (disorder)

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