Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (540 page)

   Serum IgA level is increased in ≤50% of patients.

   Serum complement is normal.

   Serum galactose-deficient IgA1 concentration is frequently elevated.

   Serum levels of glycan-specific IgG antibodies have been found to correlate with urinary protein excretion and risk of progression to ESRD or death.

Suggested Reading

Wyatt RJ, Julian BA. IgA nephropathy.
N Engl J Med.
2013;368(25):2402–2414.

INTERSTITIAL NEPHRITIS

   Definition

   This immune-mediated condition is characterized by the presence of inflammatory infiltrate in the kidney interstitium. The onset can be acute or chronic.

   Drug therapy is responsible for more than 75% of acute interstitial nephritis (AIN) cases. The major causative drugs include antibiotics (e.g., beta lactams, cephalosporins, rifampin), sulfonamide diuretics, and NSAIDs.

   Other causes include

   Infections (5–10% of cases): group A β-hemolytic streptococcal infections, diphtheria, brucellosis, leptospirosis, infectious mononucleosis, toxoplasmosis

   Systemic diseases (10–15% of cases): SLE, Sjögren syndrome, sarcoidosis

   Tubulointerstitial nephritis and uveitis (TINU syndrome)

   Toxic substances

   Who Should Be Suspected?