Nephritis is an older term used to clinically denote a child with hypertension, decreased renal function, hematuria, and edema. Technically, nephritis suggests a noninfectious inflammatory process that involves the nephron; glomerulonephritis (GN) generally is a more precise term. (See Etiology.)
Diseases that produce GN are usually classified as primary (ie, diseases in which the kidney is the primarily affected organ) or secondary (ie, systemic disorders that involve the kidneys in addition to other organs, such as systemic lupus erythematosus [SLE]). (See Differentials, Workup.)
Currently, most children with hematuria and decreased renal function who do not have a presentation consistent with postinfectious GN receive a renal biopsy, leading to a specific pathologic diagnosis. In these cases, the general terms GN and nephritis are not specific enough to be very useful for treatment or prognosis. (See Etiology, Workup.)
The term nephritis is also applied to a group of unrelated inflammatory disorders known collectively as tubulointerstitial nephritis (TIN). TIN initially affects mainly the interstitium and renal tubules.
Education about the specific nephritis is helpful. Encourage medication compliance and a healthy lifestyle (eg, maintenance of ideal body weight, abstention from smoking, exercise, avoidance of risk behaviors).
In general, glomerulonephritis (GN; ie, nonsuppurative) is produced by antigen-antibody complexes (or some other unknown mechanism) trapped in the renal parenchyma. A process of inflammation and cell proliferation, in which endothelial, mesangial, or epithelial cells are stimulated to proliferate in varying degrees, is initiated, which damages normal renal tissue. If the inflammatory process is turned off, as in acute poststreptococcal GN, recovery occurs. If the inflammatory process continues unabated, progressive loss of glomeruli and nephrons occurs (eg, as in membranoproliferative GN).
In children with tubulointerstitial nephritis (TIN), some stimulus (eg, an infection, a drug, a metabolic abnormality) initiates a tubulointerstitial inflammatory process. TIN probably occurs as a result of humoral and cell-mediated immune reactions against a hapten-protein complex. Cytokines are released and recruitment/dysregulation of inflammatory cells continues, leading to injury out of proportion to the initial insult. The occurrence of mononuclear cell infiltrates in tubulointerstitial areas is the principal pathogenic process. Tubular dysfunction is out of proportion to glomerular dysfunction.
TIN is often clinically classified as acute or chronic based on the rapidity with which renal clearance function decreases. With acute TIN, treatment or removal of the stimulus leads to resolution. In chronic TIN, differing rates of progressive renal damage persist.
In the United States, the incidence and prevalence of glomerulonephritis (GN) in the pediatric population is unknown. Acute postinfectious (most often poststreptococcal) GN has diminished in recent years but is still the most frequent type of GN. Other conditions sometimes presenting with GN, such as Henoch-Schönlein purpura, immunoglobulin A (IgA) nephropathy,  Alport syndrome, and SLE, as well as membranoproliferative GN and mesangial proliferative GN, occur infrequently.
Acute tubulointerstitial nephritis (TIN) in the United States may account for 5-10% of acute renal failure, and chronic TIN may account for 20% of chronic renal failure in children. TIN is purely a biopsy diagnosis, thus the previous estimates of TIN may be underrepresentations. Most cases of acute TIN in children are virus or medication related. Most cases of chronic TIN in children are related to chronic infection, vesicoureteral reflux, or metabolic disease (eg, oxalosis, Crohn disease).
The incidence and prevalence of glomerulonephritis and TIN on a worldwide basis are unknown. Industrialized countries tend to produce more reports.
Nephritic syndrome may occur in people of all races. The race of the child is not generally helpful in determining the primary etiology of GN. No racial differences have been reported for the incidence of TIN in children.
Acute poststreptococcal GN and IgA nephropathy occur more frequently in males than in females. SLE is more frequent in females. TIN occurs with equal frequency in both sexes.
Age-related differences in incidence
Age is not usually very helpful in determining the pathobiology of glomerulonephritis. Acute postinfectious GN usually occurs in children older than age 2 years. IgA nephropathy is rare before adolescence. Henoch-Schönlein purpura and membranoproliferative GN tend to occur in children older than age 8 years. SLE can occur in people of any age but is more frequent in adolescents.
TIN is very rare in children younger than age 5 years. Acute TIN can potentially occur in people of any age. Chronic TIN tends to occur late in childhood or adolescence with obstructive uropathy or reflux. Chronic TIN may occur in younger patients with inherited metabolic diseases.
The overall prognosis for survival in children with all forms of nephritis is good. A child with glomerulonephritis (GN) might die of potential complications of severe hypertension (eg, cerebral hemorrhage) or complications of renal failure (eg, hyperkalemia). Generally, fatal outcome in the United States is rare. Children with postinfectious GN usually have complete recovery. Children with chronic GN may develop morbidity secondary to hypertension, chronic renal failure, complications of end-stage renal disease, or complications of the primary disease (eg, SLE).
Over the last 3 decades, an important increase in the survival of children with SLE has been observed, especially in those patients with renal involvement. Management with immunosuppressive drugs (eg, intravenous [IV] cyclophosphamide, mycophenolate mofetil, rituximab, tacrolimus, and azathioprine) has changed the prognosis in these children. [2, 2, 3] Children with SLE have increased life expectancy but are now faced with new types of morbidity because of the sequelae related to the disease.
When tubulointerstitial nephritis (TIN) leads to acute or chronic renal failure, associated morbidity may occur. TIN is an unusual cause of death in children. The prognosis for complete recovery from acute renal failure in TIN is excellent. The prognosis for recovery with chronic TIN depends on the primary disease.
Primary complications associated with hypertension include:
Primary complications associated with kidney failure include:
Abnormal bone mineralization
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