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Interstitial Nephritis: Information on Causes, Diagnosis & Treatments

Kidney Waste Removal Interstitial nephritis is a disorder of the kidney that reduces the organ's ability to filter waste products and excess fluids properly. The condition can develop as a chronic (ongoing) or acute (temporary) problem.

The condition causes the kidneys to malfunction when filtering waste products from the body. This is because the kidney tubules that are to reabsorb essential organic substances and water can become swollen.

What Causes Interstitial Nephritis?

Interstitial nephritis can be caused by a variety of conditions and reactions that inflame kidney tubules. The chronic form of the condition often takes months or years to reveal even the mildest of symptoms. Alternatively, acute interstitial nephritis is often caused by medication to drugs including euros in need and other conditions including:

  • An allergic reaction to a prescription medication

  • Infections

  • Autoimmune disorders like Kawasaki disease, anti-tubular membrane disease, systemic lupus erythematosus, Sjogren syndrome, or Wegener granulomatosis.

  • Immune and neoplastic disorder that includes an acute rejection of a kidney transplant, plasma cell dyscrasias, lymphoproliferative disorder, and necrotizing vasculitis

  • Excessive potassium levels in the body's bloodstream

  • Excessive uric acid or calcium levels in the body's bloodstream

  • A side effect of specific antibiotics including methicillin, ampicillin, penicillin, sulfonamide drugs, and others.

  • Analgesic neuropathy caused by long-term drug abuse including NSAIDs (nonsteroidal anti-inflammatory drugs), acetaminophen (Tylenol), and aspirin.

  • Side effects of proton pump inhibitor drugs including thiazide diuretics, furosemide, triamterene, omeprazole, and allopurinol.

The mild and severe effects of interstitial nephritis may not be immediately detected. Some cases of the condition take two weeks or longer after beginning a new prescription medication.

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Who Gets Interstitial Nephritis?

Older adults tend to be at the highest risk for developing interstitial nephritis. This is likely because they are taking multiple prescription medications or maybe confused about how drugs should be used in combination with one another. Other individuals at high risk for developing interstitial nephritis include individuals who:

  • Chronic users of OTC (over-the-counter) pain medications

  • Have been diagnosed with sarcoidosis, a severe inflammation of the lungs

  • Have developed an autoimmune disease

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Common Symptoms

Many patients suffering from interstitial nephritis display severe to mild kidney problems symptoms, including those associated with acute kidney failure. Typically, the first noticeable sign will be decreased or increased urine output along with other symptoms including:

  • Hematuria (blood in the urine)

  • Vomiting and nausea

  • Mental status change including coma, confusion, or drowsiness

  • Fever

  • Exhaustion

  • Unexpected weight gain caused by body fluid retention

  • Rash

  • Bloated sensation

  • Elevated blood pressure

  • Swollen areas on different parts of the body

In addition to the common symptoms listed above, nearly all patients suffering from acute interstitial nephritis will have a history of infection or have just begun to take a new prescription drug.

Interstitial Nephritis and Infections

Acute cases of interstitial nephritis are often caused by primary renal infections including renal tuberculosis, acute bacterial pyelonephritis, and fungal nephritis. Any infection that reaches systemic proportions can cause direct injury to the body's kidneys. However, the injury might be the result of medications taken to treat the symptoms of the condition. As an example, some cases of acute interstitial nephritis can quickly develop from an opportunistic infection in individuals who suffer from HIV (human immunodeficiency virus).

Often, the condition develops because these patients are taking sulfonamide antibiotics and other medications that depress cell-mediated immunity. By reducing the body's ability to fight off common viruses and bacteria, the antibiotic opens the patient wide to developing acute interstitial nephritis.

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Diagnosing Interstitial Nephritis

Accurately diagnosing interstitial nephritis requires the doctor's determination that the kidneys are no longer functioning properly. To do that, the doctor will likely take a comprehensive medical history involving the patient and their ancestors. This will determine if there is a personal or family history of kidney or medical issues.

The doctor will ask the patient which drugs they are currently taking, often they take the drugs now and will take them in the future. The doctor will want to know that prescription medications and any OTC (over-the-counter) drugs the patient is currently on. This is because dietary supplements and over-the-counter pain relievers are known to cause kidney problems including kidney failure and interstitial nephritis.

While performing a complete physical examination, the doctor will listen to the lungs and heart through a stethoscope to determine if the fluid is built up in the lungs. This is often a major indicator of kidney failure. A verification of interstitial nephritis can also be determined by a blood pressure test that usually identifies most kidney problems. New weight gain is also an indicator of kidney problems. The doctor will likely order a battery of tests to evaluate the function of the organs and include:

  • CBC tests to determine a complete blood count level in the body's bloodstream

  • BUN test to measure blood urea nitrogen levels

  • Gas levels in the bloodstream that can identify acid-based imbalances and reveal levels of carbon dioxide and oxygen in the blood

  • Blood creatinine levels

  • Kidney ultrasound testing

  • Urinalysis

  • Kidney biopsy

Often, the doctor will suspect that the kidney problems are associated with an interaction with a medication or over-the-counter drug. In these cases, the condition might be able to return to normal kidney function quickly once the drug is no longer taken.

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Treating Interstitial Nephritis

The type of treatment doctor will recommend often depends on the type of kidney problem the patient has. Avoiding taking prescription medications that might be causing kidney damage can quickly relieve common symptoms. The doctor might also advise a limitation on consumed fluids and so in a daily diet that can reduce swelling and minimize high blood pressure levels. Additionally, restricting the amount of protein intake and a daily diet can help control the levels of waste product build up in the bloodstream (azotemia) that often results in acute kidney failure.

Some patients will require ongoing dialysis treatments at least three times every week. Taking strong anti-inflammatory drugs and corticosteroids is usually effective at reducing many of the signs and symptoms associated with interstitial nephritis.

Supportive Care

Doctors often recommend the withdrawal of drugs that are likely causing acute interstitial nephritis if the condition is suspected or needs management. In cases where multiple medications are being used, the doctor can reasonably substitute other drugs that produce the same benefits without the serious side effects that cause acute interstitial nephritis. Most patients can improve spontaneously once they withdraw from the drug that causes renal failure or problems including those who have had an adverse reaction after taking a new medication.


With effective and quick medical attention, most cases of interstitial nephritis can be cleared up. However, chronic kidney failure is often the result of permanent damage caused by the condition. Alternatively, acute interstitial nephritis tends to produce more severe symptoms, pain and discomfort and produce permanent (long-term) kidney damage, especially in older individuals.

The doctor must check the patient for metabolic acidosis that can occur when the kidneys lacked their ability to remove sufficient levels of acid from the body's bloodstream. This complication can lead to chronic or acute kidney failure (end-stage kidney disease).

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