340 Tubulointerstitial Diseases of the Kidney

Question 1

Classic presentation of Acute Interstitial Nephritis (AIN)

Answer 1

1. Fever
2. Rash
3. Peripheral eosinophilia
4. Oliguric renal failure after 7-10 days of treatment with Methicillin or another Beta lactam antibiotic

Question 2

NSAID-induced AIN

Answer 2

Acute renal failure with HEAVY PROTEINURIA

Rare: Fever, rash, eosinophilia

Question 3

Therapeutic Agents responsible for AIN

Answer 3

1. Antibiotics (B lactams, sulfonamides, quinolones, vanco, erythro, linezolid, minocycline, rifampin, ethambutol, acyclovir)
2. NSAIDS, COX-2 inhibitors
3. Diuretics (rarely thiazides)
4. Anticonvulsants (Phenytoin, Valproate, Carbamazepine, Phenobarbital)
5. Others: PPI, H2 blockers, captopril, mesalazine, allopurinol

Question 4

Urinalysis in AIN

Answer 4

Pyuria
White blood cell casts
Hematuria

Question 5

Allergic Interstitial Nephritis Diagnosis

Answer 5

Unexplained renal failure with or without oliguria PLUS exposure to potentially offending agent

Question 6

Allergic Interstitial Nephritis Treatment

Answer 6

1. Discontinue offending agent

2. Glucocorticoids may accelerate renal recovery and impact long-term renal survival (reserve for severe cases)

Question 7

Systemic autoimmune disorder that primarily targets the exocrine glands (lacrimal and salivary) resulting in dry eyes and mouth (“sicca syndrome”)

Answer 7

Sjogren’s syndrome

Question 8

Most common renal manifestation of Sjogren syndrome

Answer 8

Tubulointerstitial nephritis with predominant lymphocytic infiltrate

Question 9

Diagnosis of Sjogren’s syndrome

Answer 9

1. Positive anti-Ro (SS-A) antibodies

2. Positive anti-La (SS-B) antibodies

Question 10

Treatment of Sjogren’s syndrome

Answer 10

1. Glucocorticoids

2. Maintenance: Azathioprine OR mycophenolate mofetil (prevent relapse)

Question 11

Hallmark features of Tubulointerstitial Nephritis with Uveitis (TINU)

Answer 11

Lymphocyte-predominant interstitial nephritis WITHharac painful anterior uveitis (often bilateral) AND accompanied by blurred vision and photophobia

Question 12

Characteristics of TINU

Answer 12

1. Unknown etiology
2. 5% of all cases of AIN
3. Females affected 3x more than males
4. Median age of onset is 15 years
5. Extrarenal features: fever, anorexia, weight loss, abd pain, arthalgia
6. Others: Sterile pyuria, mild proteinuria, features of Fanconi’s syndrome, elevated ESR

Question 13

Treatment for TINU

Answer 13

1. Oral glucocorticoids

2. Maintenance: Methotrexate, Azathioprine, Mycophenolate mofetil (prevent relapse)

Question 14

ABSOLUTE indications for corticosteroids and immunosupresives in intersitial nephritis
(Table 340-2)

Answer 14

1. Sjogren’s syndrome
2. Sarcoidosis
3. SLE interstitial nephritis
4. Adults with TINU
5. Idiopathic and other granulomatous interstitial nephritis

Question 15

RELATIVE indications for corticosteroids and immunosupresives in intersitial nephritis
(Table 340-2)

Answer 15

1. Drug-induced or idiopathic AIN WITH: rapid progression of renal failure; diffuse infiltrates on biopsy; impending need for dialysis; delayed recovery
2. Children with TINU
3. Postinfectious AIN with delayed recovery

Question 16

Type of AIN with renal biopsy revealing more chronic inflammatory infiltrate with granulomas and multinucleated giant cells and wherein tuberculosis should be ruled out before treatment

Answer 16

Granulomatous Interstitial Nephritis

Question 17

Form of AIN with dense inflammatory infiltrate containing IgG4-expressing plasma cells and variably presents with autoimmune pancreatitis, sclerosing cholangitis, retroperitoneal fibrosis and chronic sclerosing sialadenitis

Answer 17

IgG4-related Systemic Disease

Question 18

Cause of oliguric renal failure in acute urate nephropathy

Answer 18

Acute tubular obstruction

Question 19

Uncommon but serious complication of oral Phospho-soda

Answer 19

Acute phosphate nephropathy

Should be avoided in pt with CKD
Calcium phosphate crystal deposition in tubules and interstitium

Question 20

Acute renal failure in patients with multiple myeloma in the setting of hypovolemia, infection or hypercalcemia, or after exposure to NSAIDs or radiographic contrast media

Answer 20

Light chain cast nephropathy (LCCN) / “Myeloma kidney”

Question 21

Characteristic of LCCN

Answer 21

Filtered monoclonal Ig light chains (Bence-Jones proteins) form intratubular aggregates with secreted Tamm-Horsfall protein in distal tubule

Question 22

Goals of treatment for LCCN

Answer 22

1. Correct precipitating factors (hypovolemia, hypercalcemia)
2. Discontinue potential nephrotoxic agents
3. Treat underlying plasma cell dyscrasia
   * Plasmapharesis to remove light chains is questionable

Question 23

Consequence of vesicoureteral reflux or other urologic anomalies in early chilfhood

Answer 23

Reflux nephropathy

Previously: Chronic pyelonephritis

Question 24

Abnormal retrograde urine flow from the bladder into one or both ureters and kidneys because of mislocated and incompetent ureterovesical valves

Answer 24

Vesicoureteral reflux

Question 25

Major causes of papillary necrosis

Table 340-3

Answer 25

1. Analgesic nephropathy
2. Sickle cell nephropathy
3. Diabetes with urinary tract infection
4. Prolonged NSAID use (rare)

Question 26

Results form long-term use of compound analgesic preparations containing phenacitin, aspirin, and caffeine

Answer 26

Analgesic Nephropathy

Question 27

Nephropathy due to aristolochic acid that includes Chinese herbal nephropathy and Balkan endemic nephropathy

Answer 27

Aristolochic Acid Nephropathy

Question 28

Definitive diagnosis of Aristolochic Acid Nephropathy

Answer 28

Two of the following:

1. Characteristic histology on kidney biopsy
2. Confirmation of aristolochic acid ingestion
3. Detection of aristolactam-DNA adducts in kidney or urinary tract tissue

Question 29

Most common nephropathy in patients with manic-depressive illness treated with lithium salts

Answer 29

Nephrogenic diabetes insipidus

Mechanism: lithium accumulates in principal cells of collecting duct thru epithelial sodium channel (ENaC)

Question 30

Triad of lead intoxication

Answer 30

1. “Saturnine gout”
2. Hypertension
3. Renal insufficiency

Question 31

Distinctive feature of gouty nephropathy histologically

Answer 31

Presence of crystalline deposits of uric acid and monosodium urate salts in kidney parenchyma

Question 32

Most striking defect in hypercalcemic nephropathy

Answer 32

Inability to maximally concentrate urine

Due to reduced collecting duct responsiveness to arginine vasopressin and defective transport of sodium and chloride in loop of Henle