Tubulointerstitial Nephritis

1. Sameer Sarwar

2. Ahmed Iftikhar

3. Dr. Samatbek Turdaliev

(1. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.

2. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.

3. Teacher, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.)

Abstract

Tubulointerstitial Nephritis – Tubulointerstitial nephritis (TIN) is a kidney condition in which the renal tubules and the interstitium (the tissue around the tubules) become inflamed or damaged.
TIN is divided into two main types:

●      Acute Tubulointerstitial Nephritis (ATIN): develops over days to weeks

●      Chronic Tubulointerstitial Nephritis (CTIN): progresses slowly over months to years

Causes (Etiology)

1. Acute TIN

In most cases, ATIN is caused by drug-induced hypersensitivity reactions.

Common drugs that can cause ATIN:

●      Antibiotics: penicillins, cephalosporins, sulfonamides, fluoroquinolones

●      NSAIDs: ibuprofen, naproxen, COX-2 inhibitors

●      Proton Pump Inhibitors: omeprazole, lansoprazole

●      Others: allopurinol, diuretics, H2 blockers, anti-seizure drugs

Infections:

●      Bacterial: pyelonephritis, streptococcus, legionella

●      Viral: CMV, EBV, hantavirus

Autoimmune diseases:

●      Sarcoidosis

●      Sjögren syndrome

●      Systemic lupus erythematosus (SLE)

●      TINU syndrome

2. Chronic TIN

CTIN usually occurs due to long-term exposure to toxins or metabolic disorders.

Common causes include:

●      Chronic use of analgesics, lithium, or calcineurin inhibitors

●      Heavy metals such as lead or cadmium

●      Chronic urinary obstruction or reflux

●      Hypercalcemia, hyperuricemia, hyperoxaluria

●      Congenital conditions like nephronophthisis

Clinical Features

Acute TIN

Symptoms may be mild or nonspecific.

General symptoms:

●      Fever

●      Fatigue

●      Nausea or vomiting

●      Malaise

Classic triad (rare):

●      Fever

●      Skin rash

●      Eosinophilia

Kidney-related symptoms:

●      Polyuria (increased urination)

●      Nocturia (urination at night)

●      Flank pain

●      NSAID-related ATIN may cause heavy proteinuria

Chronic TIN

Symptoms are usually absent until kidney damage becomes advanced.

Common features:

●      Slow, progressive decline in kidney function

●      Polyuria and nocturia

●      Features of Fanconi syndrome (electrolyte loss)

●      Hypertension may appear in late stages

Kidney Biopsy (Gold Standard)

A biopsy is done when:

●      Diagnosis is unclear

●      Kidney function does not improve

●      Steroid treatment is being considered

Biopsy features:

●      ATIN: inflammatory cells and tubular injury

●      CTIN: fibrosis and tubular atrophy

Treatment

1. Remove the cause

This is the most important step.

●      Stop the offending drug immediately

●      Treat infections

●      Manage autoimmune or metabolic disorders

2. Corticosteroids

●      Used mainly in drug-induced or immune-mediated ATIN

●      Prednisone 1 mg/kg/day for 4–6 weeks

●      Works best when started early

3. Supportive treatment

●      Control blood pressure

●      Manage electrolyte problems

●      Low-salt, kidney-friendly diet

●      Treat anemia and acidosis

●      Dialysis if severe kidney failure occurs

4. Second-line therapy

If steroids fail:

●      Mycophenolate mofetil

●      Azathioprine

Prognosis

Most patients with ATIN recover if the cause is removed early.
Delayed diagnosis or severe fibrosis can lead to chronic kidney disease (CKD) or end-stage renal disease (ESRD).

Reference:

-Pubmed

-USMLE Step 1&2

-Master The Board