Indinavir, an HIV medicine, can cause crystals or stones to form in the urinary tract. This side effect has been reported in adults and children and may sometimes block urine flow or affect kidney function. Drinking enough fluids helps reduce risk, but new side or back pain, blood in the urine, or trouble passing urine needs prompt medical assessment. Do not stop HIV treatment on your own.
Indinavir-related kidney stones are a recognized medication side effect. Understanding how they develop, what symptoms they may cause, and how healthcare professionals evaluate them can help people receiving this treatment know when to seek care and how to discuss prevention with their treatment team.
How can indinavir cause kidney stones?
Indinavir is an antiretroviral medicine that was used to treat human immunodeficiency virus (HIV) infection. Some of the medication is excreted through the urine, where indinavir crystals may form. These crystals can contribute to the development of urinary tract stones, a condition also called nephrolithiasis or urolithiasis.
Stones may remain in the kidney or move into a ureter, the narrow tube that carries urine from a kidney to the bladder. If a stone obstructs the urinary tract, urine may not drain normally. In some cases, indinavir-related stones have been associated with reduced kidney function, acute kidney injury, or a kidney infection. The U.S. National Library of Medicine's DailyMed prescribing information for indinavir specifically warns about these urinary complications.
How common are indinavir-related kidney stones?
The risk is clinically important because kidney stones were reported in clinical trials of indinavir. The prescribing information for Crixivan, a brand of indinavir, reported a cumulative frequency of nephrolithiasis or urolithiasis of approximately 12.4% in adults receiving the recommended dose during the trials described. The reported cumulative frequency was higher in pediatric patients, at 29%.
These figures come from historical clinical-trial data, not from a prediction of an individual person's risk. The reported rates varied across trials, and they should not be interpreted as a measure of the current risk for every person receiving treatment. Children and adolescents taking indinavir require particular attention to the medication's kidney-related risks under specialist supervision.
What symptoms may occur with indinavir-related stones?
A stone may cause symptoms when it moves through the urinary tract or blocks the normal flow of urine. Experiences can differ, and some stones may not produce noticeable symptoms initially. Symptoms that can occur include:
- Pain in the side, back, lower abdomen, or groin.
- Blood in the urine, which may make it look pink, red, or brown, although blood may only be detectable on testing.
- Pain, burning, or discomfort during urination.
- A frequent or urgent need to urinate.
- Nausea or vomiting, particularly when pain is significant.
- Passing less urine than usual or having difficulty urinating.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) identifies side or back pain, blood in the urine, painful urination, nausea, and vomiting among symptoms associated with kidney stones. These symptoms can also occur with other urinary conditions, so they need to be assessed in the context of medication use and other clinical findings.
Why can indinavir stones be difficult to detect?
Indinavir stones have an important diagnostic feature: some are radiolucent, meaning they do not show clearly on conventional X-rays. Pure indinavir stones may also be difficult to identify on standard computed tomography (CT) scans. Stones containing indinavir mixed with other materials may have different imaging appearances.
A report in the American Urological Association's Journal of Urology described indinavir-related stones that were not visible on routine imaging. This finding is clinically relevant because a scan that does not clearly show a stone may not fully explain persistent symptoms in someone taking indinavir.
Anyone undergoing evaluation for possible kidney stones should tell the healthcare professional about current or previous indinavir treatment. This information can help the clinical team interpret imaging results and decide whether further investigation is appropriate.
How do healthcare professionals evaluate possible stones?
Evaluation generally begins with a review of symptoms, medication history, fluid intake, previous urinary problems, and other relevant health conditions. The timing of symptoms in relation to indinavir treatment can also be important. A physical examination may help the clinician assess pain and identify findings that require urgent attention.
Testing may include:
- Urinalysis: A urine sample can be checked for blood, crystals, and findings that may suggest infection.
- Blood tests: These may help assess kidney function and identify other relevant abnormalities.
- Imaging: Ultrasound, CT, or other appropriate imaging may be used to look for stones or urinary obstruction. The choice depends on the clinical situation and the limitations of each method.
The NIDDK guidance on kidney stone diagnosis explains that healthcare professionals use medical history, physical examination, laboratory tests, and imaging to evaluate suspected stones. When indinavir is involved, the possibility that a stone may be difficult to visualize is an additional consideration.
What is the treatment for indinavir-related kidney stones?
Treatment depends on whether a stone is causing an obstruction, whether an infection is present, how well the kidneys are functioning, and the person's overall condition. Some cases may be managed with medical observation, adequate hydration, and pain control under clinical supervision. Other cases require a procedure to restore urine flow or address a persistent obstruction.
If the healthcare team identifies indinavir as a possible cause, it may review the antiretroviral regimen. The prescribing information states that a temporary interruption or discontinuation of indinavir may be considered when symptoms or signs of stones occur. The appropriate decision depends on the clinical circumstances and should be made by the treating healthcare professional.
Do not stop indinavir or change an HIV treatment regimen independently. Interrupting antiretroviral treatment without a coordinated plan may compromise HIV management. If symptoms develop, contact the prescribing clinician promptly so that the urinary problem and the ongoing treatment plan can be considered together.
Can drinking more fluids help prevent indinavir stones?
Adequate fluid intake is an important part of reducing the risk of indinavir-related stones. The medication's prescribing information recommends that adults drink at least 1.5 liters of liquids over 24 hours to support adequate hydration. MedlinePlus drug information for indinavir also advises drinking at least this amount of water or other liquids every day.
This amount is a medication-specific recommendation, not a universal fluid target for every person. People with kidney disease, heart failure, or another condition requiring fluid restriction should follow their healthcare professional's individualized instructions. During hot weather, illness, or periods of reduced fluid intake, it is particularly important to discuss how to maintain appropriate hydration without exceeding an established fluid limit.
Hydration can reduce risk but does not guarantee that stones will not form. Someone who has already developed a stone may need additional monitoring or changes to their treatment plan, depending on the findings of the evaluation.
When should you seek medical care?
Contact a healthcare professional promptly if you develop new side or back pain, blood in your urine, painful urination, or a noticeable change in how much urine you pass while taking indinavir. These symptoms warrant assessment rather than waiting to see whether they disappear on their own.
Seek urgent medical attention if you cannot pass urine, have severe or persistent pain, experience repeated vomiting that prevents you from keeping fluids down, or develop fever or chills with urinary symptoms or side pain. A urinary obstruction accompanied by infection can require urgent treatment.
The most useful next step is to tell the treating clinician that indinavir is part of your medication history. This can guide decisions about testing, symptom management, hydration, and whether the HIV treatment regimen needs to be reviewed.