Pre-Exposure Prophylaxis, commonly known as PrEP, is a highly effective medication regimen that significantly reduces the risk of HIV infection for individuals at high risk. While PrEP demonstrates considerable success in preventing HIV, a common concern revolves around its potential impact on kidney health. This article explores PrEP and kidney function, addressing how potential kidney changes are identified and managed for safe and effective use.
Understanding PrEP and Kidney Function
PrEP typically involves taking one of two main oral medications: tenofovir disoproxil fumarate (TDF) or tenofovir alafenamide (TAF), usually combined with emtricitabine. The kidneys play a significant role in filtering waste products and excess fluids from the blood, a process that includes processing medications.
The concern regarding kidney health stems from the tenofovir component, particularly TDF. TDF is metabolized by the kidneys and can be associated with a decline in kidney function in some individuals. Studies have shown that TDF use can lead to small but statistically significant elevations in serum creatinine and/or reductions in estimated glomerular filtration rate (eGFR). TAF, a newer tenofovir formulation, delivers the active drug more efficiently to cells. This results in lower bloodstream concentrations and less kidney exposure, minimizing the kidney impact seen with TDF.
Identifying and Monitoring Kidney Changes
Regular kidney function tests are used to detect and track potential kidney issues while on PrEP. Healthcare providers monitor estimated glomerular filtration rate (eGFR) and creatinine levels. Creatinine is a waste product from muscle turnover that healthy kidneys filter out of the blood at a consistent rate. If kidney function declines, creatinine levels in the blood will rise.
The eGFR is a calculated value that estimates how well the kidneys are filtering waste from the blood each minute. A normal eGFR is typically 90 mL/min/1.73m² or higher, though values as low as 60 mL/min/1.73m² can be normal. If the eGFR consistently falls below 60 mL/min/1.73m² for three months or more, it may indicate chronic kidney disease. Noticeable symptoms of impaired kidney function, such as swelling in the feet or ankles, fatigue, or changes in urination patterns, are rare and typically only appear in more advanced stages of kidney disease.
Minimizing Kidney Impact and Management
Several factors can increase the risk of kidney issues for individuals taking PrEP, including pre-existing kidney conditions, older age, and the concurrent use of other medications that can be harmful to the kidneys. For instance, regular use of non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen can contribute to kidney problems when taken with tenofovir. Additionally, certain dietary supplements, such as creatine, can artificially elevate serum creatinine levels, making kidney function test results harder to interpret.
To minimize kidney impact, healthcare providers may recommend TAF-based PrEP, which has shown a lower impact on kidney health compared to TDF. Maintaining good hydration also supports overall kidney function. If a decline in kidney function is observed, medical management steps may include adjusting the PrEP dosage, switching to a different PrEP medication, or in rare cases, discontinuing PrEP under careful medical supervision. For individuals with a baseline eGFR around 60 mL/min/1.73m², close monitoring is recommended. Starting PrEP is generally not advised if the eGFR is consistently below this threshold.
The Broader Picture of PrEP and Kidney Health
While concerns about kidney health with PrEP exist, these issues are generally uncommon, mild, and manageable with appropriate medical oversight and consistent monitoring. Studies indicate that declines in kidney function are typically small and often reversible upon stopping PrEP. For most individuals, the substantial benefits of PrEP in preventing HIV infection outweigh the potential, manageable risks to kidney health. Open communication with a healthcare provider is important to ensure that PrEP is used safely and effectively, with individualized care that considers personal health factors and potential risks.