Introduction

• Acute interstitial nephritis is a kidney or renal dysfunctioning condition where being affected by it can rapidly decline the renal functioning.
• The word itself describes the nature of the disease and the term “Acute” denotes the sudden onset of disease with less than 3 months of duration , “Interstitial” denotes the surrounding area or tissue around the nephron ,”Nephritis” denotes inflammation to the nephron /

surrounding regions of the kidney .

Causes 

The majority of the disease can happens due to long-term use of

I.Medications such as 

Almost two thirds of cases are due to long-term use of medication 

• Hypersensitivity drugs 
• Antibiotics such as beta lactams,quinolones,cephalosporins,fluoroquinolones etc
• NSAIDS (Ibuprofen)
•  Proton pump inhibitors (pantoprazole)
• Diuretics (Furosemide,Thiazides)
• Allopurinol
• Phenytoin

II.Infections

• 10-15% of cases have infections as underlying cause 

• Attack from microorganisms such as E.coli,campylobacter,salmonella, streptococcus
• Viral infections Such as measles ,mumps ,HIV,CMV,EBV
• Fungal infections by histoplasmosis ,coccidiomycosis 
• Protozoal infections such as toxoplasmosis

III.Systemic conditions

• It accounts for 10-15% of cases 
• Systemic or immune diseases such as sjogren’s syndrome ,lupus and sarcoidosis
• 10-20% of Acute kidney injury is due to Acute interstitial nephritis 

IV.Idiopathic 

• 5-10% of cases have unknown etiology
• Diseases such as Anti-TBM,TINU syndrome

V.Too little potassium in blood (or) Too much calcium/uric acid in blood .

Clinical features

• Asymptomatic
• Non-oliguric Acute kidney injury 
• Nausea ,vomiting 
• Malaise
• Flank pain 
• Frequent urination 
• Swelling of feet 
• Pain or burning sensation during urination 

Specific symptoms 

• Drug induced- Acute interstitial nephritis has a classic triad in almost 10% cases

• Skin rash
• Low -grade fever 
• Eosinophilia 

• Infections 

• Fever 
• More specific infections to underlying infection or illness                                             

Pathophysiology

• In Drugs induced AIN , medications acts as haptens /proteins which binds to tubular cells to initiate a immune response 
• May be for several weeks to months 

• In infections induced AIN, Microorganisms antigens gets deposited in to interstitium which activates the immune response which on mediation can damage the kidneys

Diagnosis 

• Urinalysis
• Blood test
• Kidney biopsy is recommended for definitive diagnosis or for patients who are not responding even after withdrawal of the drugs or managing underlying conditions 
• But biopsy is contraindicated in bleeding diathesis, solitary kidney,ESRD, Uncontrolled Hypertension,sepsis 
• Imaging studies such as Renal ultrasonography can be used to study the increased or decreased size 

Lab findings  

• Sterile pyuria
• Leukocyte / WBC casts 
• Proteinuria- subnephrotic stage
• Microscopic Hematuria casts ,rare
• Renal tubular 
• Peripheral eosinophilia 
• Eosinophiluria-predictive value of 38% is positive 
• Serum creatinine profile -elevated BUN and creatinine suggest variable degree of renal injury 
• Hyper /hypokalemia ,hyperchloremic metabolic acidosis suggest tubulointerstitial injury
• Fractional excretion of sodium (>1%)
• Elevated transaminase levels in drug induced injuries  

Treatment

• Supportive care 
• Withdrawal of drugs and substitute with alternative drugs 
• Managing fluid and electrolyte balance and hydration

• Removing the underlying etiology 
• Corticosteroids should be initiated early which can results of recovery within 2 hours 
• Prednisone -1mg/kg,orally -2 to 3 weeks followed by gradually tapering dose over 3-4 weeks 
• If not responded , cyclophosphamide is considered 
• In situations of severe damage to kidneys dialysis is considered 

Prognosis 

• Patients who discontinue medications can recover within 2 weeks of onset and more likely to recover than those who remained continuing for more than 3 or 4 weeks 
• Adverse prognostic factors include inflammation occurring diffusely on biopsy ,elevated number of neutrophils,severity of interstitial fibrosis.
• There is a good prognostic value otherwise 

Frequently asked questions 

1.Is Acute interstitial nephritis serious?

• It is serious but can be treated if identified early 
• In AIN, spaces between the nephrons get inflamed and reduce the functional ability of kidneys to filter.
• And in few cases they may end up in kidney failure 

2.What usually causes Acute interstitial nephritis?

• Usually allergic reactions to medicated drugs and infections or other idiopathic conditions can cause acute interstitial nephritis

3.How does Acute interstitial nephritis feel like?

• Can range from mild to moderate or even severe kidney problems
• In almost half of the cases there is a decreases urine output and signs of acute kidney failure 
• The symptoms include nausea ,vomiting malaise,flank pain,edema etc

4.How is Acute interstitial nephritis diagnosed ?

• Some suggest renal biopsy but not  every patients should undergo this diagnostic test
• In few biopsy with histopathological findings shows plasma cells and lymphocytic infiltrates in the peritubular areas of interstitium with edema 
•  other tests include urine analysis also provide the evidence 

5.Is Acute interstitial nephritis reversible?

• It totally depends upon the etiological cause 
• In infection induced or idiopathic reasons then the disease is reversible
• If drug induced(NSAIDs) then there is a chance of permanent insufficiency in almost 40% of cases 

6.What medications can cause nephritis?

• NSAIDS , Antibiotics, anti-inflammatory drugs and proton pump inhibitors

7.Can nephritis be cured 

• May not be cured ,but can be treated as mentioned earlier
• Proper treatment can keep the condition on track and protect the kidneys
• It is important to follow the expert advice and instructions
• If kidney failure occurred there is no other way except undergoing dialysis or Transplantation

8.Does nephritis cause fatigue ?

• Yes,toxins ,metabolites does not filter properly into the urine instead ,build up in body causing swelling and fatigue 

9.Can UTI cause nephritis

• Yes,Infections can spread from urinary tract to kidneys
•  It can result in acute or even chronic Interstitial nephritis

10.Complications of Acute Interstitial nephritis

• Hypertension
• Increased levels of cholesterol
• Chronic kidney disease or failure 

11.What type of Hypersensitivity is acute interstitial nephritis

• It is a drug Hypersensitivity reaction or DHR
• can be manifested in a week or 2 after exposure to certain drugs 

12.Does Acute interstitial nephritis cause Acute kidney injury?

• Classically Acute interstitial nephritis presents as acute kidney injury after the use of drugs or underlying systemic  infections and sometimes often associated with pyuria,hematuria , proteinuria

13.Does Interstitial nephritis cause proteinuria?

• Not always but can cause proteinuria ranging from moderate to heavy proteinuria due to cytokine like permeability increasing factor secreted by inflammatory cells

14.Is Acute interstitial nephritis hereditary?

• The inheritance of one mutated gene from an affected parent can lead to disease
• Disease is autosomal -dominant conditions half of the offspring will have a chance of disease 

15.What is allergic interstitial nephritis?

• It is one of the commonest form of acute interstitial nephritis 
• The reason includes exposure to drugs 

16.Does Acute interstitial nephritis cause pain ?

• If the cause of pyelonephritis ,symptoms of fever ,nausea ,vomiting and lower back pain is most common 

17.What medications help kidney function?

• Angiotensin renin blockers and Angiotensin converting enzymes inhibitors decrease blood pressure and slow down the loss of kidney function 
• Additionally they delay the progression of kidney failure

18.What fruits are great for kidneys?

• Pineapple ,grapes ,cranberries and apples are known to have known  anti Inflammatory property and helps to heal, benefit the kidney health

19.How do you treat acute interstitial nephritis naturally?

• 2 teaspoons of crushed parsley juice with 1 spoon of honey consumed 3 times daily  can improve the condition
• 1 glass of carrot juice + 1 tablespoon of lemon juice and honey consumed once daily for everyday during mornings on early stomach is another proven ayurvedic remedy 

20.Natural diet which improves kidney health?

• As coconut water is an excellent diuretic ,while consuming 2 glasses of  it daily can benefit  
• Including bananas around 3-5 and 1 papaya in your diet.