Tubulointerstitial Nephritis (TIN) is a kidney disorder characterized by inflammation affecting the renal tubules and the surrounding interstitial tissue, rather than the glomeruli. It is an important cause of both acute and chronic kidney dysfunction and is frequently encountered in nephrology practice due to its strong association with medications, infections, autoimmune conditions, and systemic diseases. In the UAE, drug-related and infection-related forms of TIN are commonly observed.

The tubules play a critical role in reabsorbing water, electrolytes, and essential nutrients from the filtered blood. In TIN, inflammation disrupts these processes, leading to impaired urine concentration, electrolyte imbalance, and reduced overall kidney function. The condition may present acutely or develop gradually into a chronic form, depending on the underlying cause and duration of injury.

Common causes of TIN include hypersensitivity reactions to medications such as antibiotics, non-steroidal anti-inflammatory drugs, and certain acid-reducing agents. Infections, particularly bacterial and viral illnesses, may also trigger inflammation. Autoimmune disorders, metabolic conditions, and systemic inflammatory diseases contribute to chronic forms of tubulointerstitial damage.

Clinical presentation varies. Acute TIN may present with sudden decline in kidney function, reduced urine output, fatigue, nausea, and electrolyte disturbances. Some patients develop fever, rash, or joint pain in drug-induced cases. Chronic TIN often presents insidiously, with gradual loss of kidney function, anemia, polyuria, and difficulty concentrating urine, leading to excessive thirst and urination.

Diagnosis is based on clinical history, laboratory evaluation, and imaging. Blood tests reveal impaired kidney function and electrolyte abnormalities, while urine testing may show mild proteinuria or inflammatory markers. Kidney biopsy is sometimes required to confirm diagnosis and assess the extent of damage, particularly when the cause is unclear or kidney function does not improve with initial treatment.

Management focuses on identifying and removing the underlying cause, such as discontinuing the offending medication or treating the associated infection. Supportive care includes optimization of fluid and electrolyte balance and close monitoring of kidney function. In selected cases, anti-inflammatory or immunosuppressive therapy may be required to control persistent inflammation.
Prognosis depends on early recognition and prompt treatment. Many patients experience partial or complete recovery if the condition is identified early. However, prolonged or recurrent tubulointerstitial injury may lead to chronic kidney disease. Long-term nephrology follow-up is essential to monitor renal recovery and prevent progression.