Do you know drug-associated interstitial nephritis?
Drug-associated interstitial nephritis is the most common type of drug-associated kidney damage, caused by drugs, with clinical manifestations of renal insufficiency and pathological damage mainly involving the renal interstitium and tubules, without or with only minor glomerular or renal vascular damage. According to the urgency of the onset, it can be divided into drug-related acute interstitial nephritis and chronic interstitial nephritis. Mou Shan, Department of Nephrology, Shanghai Renji Hospital
People often tend to ignore drug-induced interstitial nephritis, but in fact drug-related interstitial nephritis is very important. Some data show that drug-related acute interstitial nephritis is the most common cause of acute renal failure, accounting for about 15%; while in patients on renal dialysis treatment, perhaps 10% of patients come from chronic interstitial nephritis.
What are the drugs that can trigger interstitial nephritis?
There is a wide variety of drugs involved, which can be single drugs or a mixture of drugs that cause the disease. There are hundreds of disease-causing drugs reported in the literature, and this number is increasing as new drugs become available. Among them, the most common ones are mainly antibiotics, antipyretics and analgesics (e.g., NSAIDs), and herbal medicines (containing aristolochic acid).
Here we list several common drugs that have been reported to cause acute interstitial nephritis: antibiotics: gentamicin, penicillin G, amoxicillin, ceftriaxone, levofloxacin, moxifloxacin, acyclovir, lincomycin, clindamycin; antipyretic analgesics: indomethacin, ibuprofen, diclofenac, aspirin; antihypertensive drugs: captopril, amlodipine; diuretics: aminopterin, furosemide. Others: cyclosporine A, allopurinol, omeprazole, cimetidine, etc.
Common drugs that cause chronic interstitial nephritis are antipyretic analgesics, herbs containing aristolochic acid (e.g., guanxi, qingmu xiang, aristolochia, guanxi, tianxian vine, hosin, etc.), pro-exemptin binding agents, and lithium preparations.
What are the clinical manifestations of interstitial nephritis?
The clinical manifestations of acute interstitial nephritis are diverse and include: ① systemic allergic reactions, such as skin rash, pruritus, pustules, purpura, etc., after drug administration, elevated peripheral blood eosinophils, mild arthralgia and lymph node enlargement in a few cases. (ii) Abnormal urinalysis, including aseptic leukocyturia, urinary eosinophilia, etc. (iii) Short-term hyperalgesia, renal glycosuria, markedly elevated urinary enzymes or urinary low-molecular protein, renal tubular acidosis, which may be accompanied by rising creatinine and anemia, and ultrasound showing normal or mildly enlarged size of both kidneys.
The clinical manifestations of chronic interstitial nephritis are not specific. About 25% to 40% of patients have sudden onset of hematuria, renal colic or detached necrotic tissue found in the urine, suggesting concomitant renal papillary necrosis. Ultrasound may show a decrease in kidney size, and CT scan may show a decrease in kidney size, bumpy shape, and calcified renal papillae, which may help to clarify the diagnosis.
It is important to note that antibiotics triggering acute interstitial nephritis may be caused by physical allergy, but patients do not necessarily have allergic symptoms. Most patients will have flu-like symptoms and aseptic pusuria on urinalysis, at which point extensive eosinophilic infiltration of the renal interstitium is seen if a renal biopsy is performed. Patients with chronic interstitial nephritis triggered by long-term pain medication usually have mild clinical symptoms and are less likely to have edema, proteinuria, or hematuria. Some patients have a combination of abnormal renal tubular function and “frequent nocturia”.
How to diagnose drug-related interstitial nephritis?
The diagnosis should be considered when there is an acute or chronic renal impairment of unknown origin, a history of suspected drug use, and clinical manifestations as described above (including abnormal renal tubular function, systemic drug allergy, eosinophilia, etc.). However, confirmation of the diagnosis depends on pathological diagnosis by renal biopsy.
How to treat drug-related interstitial nephritis?
First, all suspected medications should be discontinued immediately and a prompt hospital visit should be made.
Patients with drug-associated acute interstitial nephritis are treated with glucocorticoids, which can rapidly relieve allergic symptoms and speed up the recovery of renal function. Dialysis support therapy is recommended for patients who meet the indications for dialysis.
There is no recognized good therapy for drug-related chronic interstitial nephritis, and the key to treatment is early diagnosis and discontinuation of suspected drugs. A few authors recommend short-term glucocorticoid therapy, but the long-term prognostic effect is unclear.
It is worth noting that the suspected drugs in question should be avoided in the future.
What else should we be aware of?
The kidney is an important organ in our body. It is not only responsible for the production and excretion of urine, but also one of the important endocrine organs that regulate the stability of the body’s internal environment. Most of the drugs we take have to be metabolized by the kidneys, which are very delicate, and long-term or large amounts or incorrect use of drugs can easily lead to the destruction of kidney function. Once kidney failure occurs and enters uremia, which requires long-term kidney replacement therapy, it will bring heavy economic burden to individual families and society, and also make their quality of life greatly reduced. Therefore, we should take good care of our kidneys, use drugs carefully under the guidance of doctors, monitor kidney function regularly to understand the kidney condition and adjust the medication in time if necessary; once there is an unexplained decrease in kidney function and drug-related interstitial nephritis is clinically suspected, kidney puncture should be actively performed to clarify the diagnosis and treat it early. We should treat the use of drugs with the right attitude and say “no” to drug-related interstitial nephritis!