Tubulointerstitial nephritis (TIN)

Although the tubules and the interstitium are distinct functional entities, they are intimately related.Injury involoving one of them invariably results in damage to the other.

Acute tubulointerstitial nephritis(TIN)

In approximately 70% of the cases ,acute TIN is due to a hypersensitivity reaction to drugs, most commonly drugs of the penicillin family and NSAIDs .15% are idiopathic and 5% are caes of tubulointerstitial nephritis with uveitis (TINU) syndrome.

Drug induced acute TIN

Patients present with fever, arthralgia,skin rashes and acute oliguric or non-oliguric renal failure.Many have eosinophilia and eosinophiluria.

Rarely, NSAIDs can cause a glomerular minimal change lesion in addition to TIN and present as the nephrotic syndrome.

Treatment involves withdrawal of offending drugs.High-dose steroid therapy( prednisolone 60 mg daily) is commonly given.

Patients may require dialysis for management of the acute renal failure.Most patients make a good recovery in the kidney function, but some may be left with significant interstitial fibrosis and a persistent high serum creatinine.

Infection causing acute TINAcute pyelonephritis leads to inflammation of the tubules, producing a neutrophilic cellular infiltrate.TIN can complicate systemic infections with viruses( hantavirus,EBV,HIV,measles, adenovirus), bacteria(Legionella,leptospira,streptococci,Mycoplasma,Brucella,Chlamydia) and others ( Leishmania,Toxoplasma).In immunocompromised patients such as post-renal transplantation,CMV,and herpes simplex virus can cause acute TIN in the renal graft.Treatment involves eradication of infection by appropriate antibiotics or antiviral agents.

Acute TIN as a part of multisystem inflammatory diseases

Several non-infectious inflammatory disorders such as Sjogren ‘s syndrome,SLE,and Wegener’s granulomatosis can cause acute or chronic TIN rather than GN.Sjogren’s syndrome may additionally present as renal tubular acidosis.These heterogenous conditions with TIN generally respond to steroids.

TINU syndrome

IN this syndrome, uveitis generally coincides with acute TIN.It is common in children ,but has been reported in adulthood.Among adults it is more common in females, but its cause remains unknown.Patients presents with wt. loss, anaemia and raised ESR .A prolonged course of steroids leads to improvement in both renal function and uveitis.

Chronic tubulointerstitial nephritis

*Causes are:

Common Uncommon

.Reflux nephropathy .Alport’s syndrome

.NSAIDs .Balkan nephropathy

and herbal nephrop-

thy.

.DM .Irradiation

.Sickle cell disease or .Sjogren’s syndrome

Trait

.Cadmium or lead .Hyperuricaemic nephropa-

intoxication thy .

Chronic TIN changes evolve in progressive primary glomerular or vascular disease of the kidney,where its severity is a better predictor of long term survival than the primary site of insult.

The patient usually either presents with polyuria and nocturia ,or is found to have proteinuria or uraemia.Proteinuria is usually slight( less than 1 g daily).Papillary necrosis with ischemic changes to the papillae occurs in a number of tubulointerstitial nephritidis,e.g., analgesic abuse,DM,sickle cell disease or trait

Analgesic nephropathy

The chronic consumption of large amounts of analgesics( especially those containing phenacetin) and NSAIDs leads to chronic TIN and papillary necrosis.Analgesic nephropathy is twice as common in women as in men and present typically in middle-age.Patients are often depressed or neurotic.Presentation may be with anaemia,chronic renal failure,UTIs , haematuria, or urinary tract obstruction( owing to sloughing of a renal papilla).

Chronic analgesic abuse predisposes to the development of uroepithelial tumors.The consumption of the above analgesia shoukd be discouraged.If necessary,dihydrocodeine or paracetamol is a reasonable alternative.This may result in the arrest of the disease and even improvement in the function.UTI ,hypertension (if presents) and saline depletion will require appropriate management.The development of flank pain or unexpectedly rapid deterioration in renal function should prompt ultrasonography to screen for urinary tract obstruction due to a sloughed papilla.