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SariAaltonen

Glomerulonephrites

Essentials

  • Findings almost always include some degree of haematuria and proteinuria Proteinuria.
  • Clinical signs often include hypertension and oedema. In patients with glomerulonephritis, it is important to treat even mild hypertension effectively.
  • In rapidly progressive glomerulonephritis (RPGN), renal function deteriorates progressively over a few days or months. Workup and treatment of RPGN should be started urgently, often as an emergency case.
  • The clinical pictures of different types of glomerulonephritis vary and cannot be used to define the type of disease with certainty. The course of disease also varies in patients with the same type of disease.
  • The classification of glomerulonephritis into different groups has changed in recent years from a classification based on histology to one based more on pathophysiology.
  • Accurate diagnosis of glomerulonephritis nearly always requires renal biopsy.

Pathogenesis

  • A group of inflammatory diseases of the renal glomeruli leading to structural and functional changes, such as changes in glomerular permeability
  • The disease is initiated by immunological mechanisms, probably based on an underlying genetically defined reaction pattern (induced by the patient's own or foreign antigens, microbes, medicines).
  • The condition occurs either as a primary disease restricted to the kidneys or part of a systemic disease (SLE, systemic vasculitis).
  • May be associated with e.g. infections, complement system disorders, haematological diseases and different malignancies.

Clinical pictures of different types of glomerulonephritis

  • Glomerulonephritis can have various clinical presentations.
    • Clinical picture of nephritis
    • Rapidly progressive glomerulonephritis
    • Nephrotic syndrome
    • Asymptomatic haematuria and/or proteinuria
    • Renal failure
  • Different types of glomerulonephritis may have a similar clinical picture and, on the other hand, the clinical picture of the same type of glomerulonephritis may vary in individual patients.
  • The clinical picture often includes hypertension and, in patients with nephrosis, oedema.
  • A nephritic clinical picture is an acute condition and may lead to acute renal failure but the symptoms may also be milder and self-limited.
  • Plasma creatinine levels may be normal or elevated and the estimated glomerular filtration rate (eGFR) may be normal or decreased.
  • Untreated, all forms may lead to chronic renal failure.
  • Chronic forms of disease are often asymptomatic.
  • Glomerulonephritis may be associated with many systemic diseases, of which SLE Systemic Lupus Erythematosus (Sle) and different types of vasculitis are the most significant Vasculitides. In the follow-up of systemic diseases, urinary findings should be monitored, even if infrequently, and especially in association with any disease activation.

Acute nephritis or rapidly progressive glomerulonephritis (RPGN)

Aetiology

  • Primary renal disease caused by an infection or a systemic disease
  • Often associated with vasculitis (granulomatous polyangitis [GPA], microscopic polyangitis [MPA]), SLE or basement membrane nephritis (Goodpasture's syndrome).
  • Acute glomerulonephritis occurring after a streptococcal disease (1-3 weeks after the primary infection) is an example of a classic postinfectious glomerulonephritis.
  • Acute glomerulonephritis may also occur in connection with or after other infections (endocarditis, shunt nephritis, sepsis, viral hepatitis).
  • Henoch-Schönlein purpura nephritis, IgA nephropathy and membranoproliferative glomerulonephritis can sometimes be rapidly progressive.

Symptoms and findings

  • Haematuria, often red cell casts in urine (urinalysis, urine cells) ("nephritic sediment"), proteinuria (urine albumin/creatinine ratio, 24-hour urinary protein excretion)
  • Often elevated plasma creatinine levels
  • Oedema, hypertension
  • Depending on the aetiology, often additionally general symptoms (in patients with systemic disease often mild fever, fatigue, rash, respiratory, joint or gastrointestinal tract symptoms)
  • In rapidly progressive glomerulonephritis, renal function deteriorates progressively within a few days or weeks.
  • Laboratory tests may help to confirm the diagnosis.
    • Positive ANCA antibodies in patients with vasculitis
    • Hypocomplementaemia (serum complement C3, serum complement C4) and positive DNA antibodies in patients with SLE
    • Positive basement membrane antibodies in patients with basement membrane nephritis
    • Serum and urine protein fractions can reveal paraproteinemia.
    • Cryoglobulins
    • Serum antistreptolysin, serum antistaphylolysin can reveal a preceding infection.

Treatment and prognosis

  • Treatment according to aetiology, and supportive treatment: treatment of hypertension and renal failure Treatment of Chronic Renal Failure
  • For postinfectious glomerulonephritis treatment of the infection and supportive treatment
    • For prolonged cases sometimes glucocorticoids
    • The prognosis is good in children; in adults, the disease may become chronic.
  • For vasculitis, SLE nephritis and basement membrane nephritis, immunosuppressive treatment (glucocorticoid, cyclophosphamide, azathioprine, mycophenolate, rituximab)
  • Treatment for rapidly progressive glomerulonephritis should be started urgently.
    • Initially often a massive dose of glucocorticoids i.v.
    • For basement membrane nephritis and vasculitis plasma exchange
  • For rapidly progressive glomerulonephritis sufficiently aggressive immunosuppressive treatment started early enough will improve the prognosis decisively.
  • Treatment and follow-up take place in specialized care during the active phase of the disease. After the end of possible immunosuppressive therapy in a stable remission situation, follow-up may also be transferred to primary care.

Clinical picture of nephrosis

Aetiology

  • Focal segmental glomerulosclerosis (FSGS)
    • Among the most common form of glomerulonephritis causing nephrotic syndrome in adults
    • May be primary or secondary to, for example, obesity or loss of nephrons.
  • Minimal change glomerulonephritis (MCN)
    • The most common form of glomerulonephritis causing nephrosis in children but may also occur in adults
    • Triggered by various medicines, infections
    • Adults sometimes have this as a paraneoplastic phenomenon.
  • Membranous glomerulonephritis (MGN)
    • A common cause of nephrosis in adults
    • May be either idiopathic or associated with other diseases (SLE) or malignancies, for instance.
    • Antibodies to phospholipase-A2-receptor (PLA2R) can often be detected in the idiopathic disease, in a small share of patients antibodies to thrombospondin type-1 domain containing 7A (THSD7A).
  • Membranoproliferative glomerulonephritis (MPGN)
    • There may be various underlying disorders such as infections (viral hepatitis, endocarditis, shunt nephritis), SLE, acquired or congenital disorders of the complement system or malignancies (solid tumours or haematological malignancies).
  • IgA nephropathy Iga Nephropathy may sometimes present with a clinical picture of nephrosis.

Symptoms and findings

  • Oedema, weight gain
  • Proteinuria > 3 g/day, plasma albumin < 30 g/l, often additionally haematuria
  • Sometimes elevated plasma creatinine levels and hypertension
  • Severe nephrosis may be associated with acute renal failure.
  • Hyperlipidaemia, increased risk of venous thrombosis

Treatment and prognosisInterventions for Minimal Change Disease in Adults with Nephrotic Syndrome, Immunosuppressive Treatment or Alkylating Agents for Idiopathic Membranous Nephropathy

Clinical picture of haematuria-proteinuria

Aetiology

  • May be primary or associated with systemic diseases.
  • IgA mesangial glomerulonephritis Iga Nephropathy is the most common type of primary glomerulonephritis causing haematuria and proteinuria.
  • Membranous glomerulonephritis, membranoproliferative glomerulonephritis and secondary focal segmental glomerulosclerosis, ANCA vasculitis confined to the kidneys and SLE may also sometimes present with haematuria and proteinuria.

Symptoms and findings

  • Often an asymptomatic, incidental finding
  • Haematuria (urinalysis, urine cells) and/or proteinuria < 3 g/day
    • Patients with IgA mesangial glomerulonephritis often have periods of macrohaematuria in association with infections.
  • Plasma creatinine level normal or elevated
  • Hypertension
  • The same laboratory tests as mentioned for RPGN can help in diagnosis.

Treatment and prognosis

  • Treatment of hypertension. If urinary protein levels are > 0.5 g/day, primarily an ACE inhibitor or ATR blocker should be given Antiproteinuric and Renoprotective Effects of ACE Inhibitors and Angiotensin II Receptor Blockers.
  • Treatment of renal failure Treatment of Chronic Renal Failure.
  • Treatment depending on aetiology
    • For vasculitis or SLE usually immunomodulatory treatment. For IgA mesangial glomerulonephritis, glucocorticoid therapy should be considered if the daily urinary protein levels do not fall to below 1 g/day or if the GFR has decreased or is starting to decrease.
  • If in membranous glomerulonephritis or focal segmental glomerulosclerosis proteinuria stays below 2 to 3 g/day, the long-term prognosis is quite good and no immunomodulatory treatment is needed.
  • In chronic proteinuric kidney disease, an SGLT2 inhibitor improves prognosis and is recommended to be started if GFR > 25 ml/min.
  • Initial treatment with possible immunosuppression in specialized care; at a later stage, treatment and follow-up is often transferred to primary care.

Referral indications

  • In primary care, the following can usually be monitored:
    • Isolated microhematuria (normal creatinine and no proteinuria) without a suspicion of an underlying disease. Does not require renal biopsy, follow-up every 1-2 years and referral if the situation changes.
    • Isolated minor (< 1 g/day) proteinuria without a suspicion of a systemic disease. Follow-up annually and referral if the situation changes. In young patients (< 30 yrs), however, readily consultation.
  • Non-urgent referral
    • Haematuria, proteinuria and normal or stable creatinine
  • Urgent referral
    • Gradually increasing creatinine
    • Nephrotic-level proteinuria (> 3 g/day) and profuse oedema
    • Suspected SLE or vasculitis
  • Emergency referral
    • Severe renal failure or suspected RPGN
    • Very profuse oedema and oliguria in nephrosis