Lyme disease can affect the kidneys, though it does so far less often than it causes joint pain, rashes, or neurological symptoms. When kidney involvement does occur, it typically takes the form of glomerulonephritis, an immune-driven inflammation of the kidney’s tiny filtering units. The connection is better studied in dogs than in humans, and published human cases remain relatively few, which has led some clinicians to underestimate the possibility. But a growing number of case reports and at least one large cohort study suggest the link is real and worth taking seriously.
How Lyme Disease Harms the Kidneys
The bacterium behind Lyme disease, Borrelia burgdorferi, does not appear to infect kidney tissue directly the way it colonizes joints or the nervous system. Instead, the damage is largely collateral, driven by the body’s own immune response to the infection. A 2019 review in Néphrologie & Thérapeutique described three overlapping mechanisms: immune complex deposits that settle in the kidney’s filtering membranes, overactivation of a specific protein on the surface of podocytes (the specialized cells that help filter blood), and the infiltration of inflammatory cells into kidney tissue.1PubMed. Lyme nephritis in humans: Physio-pathological bases and spectrum of kidney lesions In simpler terms, the immune system ramps up to fight the Lyme infection, and some of the fallout from that fight lands on the kidneys.
This matters for diagnosis because the kidney trouble may not appear at the same time as the classic early signs of Lyme, like the bull’s-eye rash or flu-like symptoms. By the time kidney involvement shows up, the infection may have been present for weeks or months, and the connection to a tick bite can be easy to miss.
What Kind of Kidney Damage Shows Up on Biopsy
Lyme-related kidney disease is not a single entity. When physicians perform biopsies on affected patients, they find a range of patterns. One of the more frequently reported is IgA nephropathy, in which a particular antibody (IgA) accumulates in the kidney’s filtering structures. In a case documented in the Journal of Renal Injury Prevention, biopsy revealed mesangial expansion and focal proliferative IgA nephropathy, with strong immunofluorescence staining for IgA and a complement protein called C3. That patient arrived with creatinine levels above 5 mg/dL, well into the range of acute kidney failure.2PubMed Central. Post-infectious glomerulonephritis presenting as acute renal failure in a patient with Lyme disease
Other biopsy findings have included membranoproliferative glomerulonephritis, a pattern in which immune complexes thicken the capillary walls of the filtering units. In a report of two cases, a 57-year-old woman developed this lesion along with volume overload, high blood pressure, and rapidly worsening kidney function, while a 40-year-old man with a history of microscopic blood in his urine saw his previously quiet IgA nephropathy flare up after a tick bite, progressing to heavy protein loss and visible blood in the urine.3PubMed. Lyme disease-associated glomerulonephritis A separate case report described minimal change disease, a pattern more commonly associated with childhood nephrotic syndrome, appearing in a patient with chronic Lyme borreliosis.4PubMed Central. Chronic Lyme borreliosis associated with minimal change glomerular disease: a case report
The variety of biopsy findings is part of why Lyme nephritis has been hard to define as a neat clinical syndrome. There is no single “Lyme kidney lesion.” The common thread is immune-mediated damage tied to Borrelia infection, but the particular pattern of that damage varies from patient to patient.2PubMed Central. Post-infectious glomerulonephritis presenting as acute renal failure in a patient with Lyme disease
Why So Few Human Cases Are Reported
If Lyme disease affects hundreds of thousands of people every year in the United States alone, why are kidney complications so rarely documented? There are a few plausible reasons. First, Borrelia burgdorferi is difficult to detect in tissue. Standard blood tests for Lyme look for antibodies rather than the bacterium itself, and when the kidney is biopsied, identifying Borrelia organisms in the tissue is technically challenging. Second, when a patient develops glomerulonephritis, clinicians may attribute it to other causes, especially if the classic Lyme symptoms have already resolved or were never noticed. Third, mild kidney inflammation may go undetected if the patient’s primary complaints are joint pain or fatigue and urinalysis is not part of the workup. As the authors of the case report cited above note, difficulties in identifying Borrelia may be one reason these reports are so scarce.2PubMed Central. Post-infectious glomerulonephritis presenting as acute renal failure in a patient with Lyme disease
The upshot is that Lyme nephritis in humans could be genuinely rare, or it could be underdiagnosed because nobody is looking for it in the right patients. Right now, the evidence points to somewhere in between: it is probably uncommon, but not as uncommon as the handful of published case reports might suggest.
Acute Kidney Injury and Lyme
Some patients develop outright acute kidney injury (AKI) rather than a slow-building glomerulonephritis. A case presented at a CHEST conference described a patient admitted for sepsis and fever of unknown origin whose initial workup revealed acute kidney injury with elevated creatinine and other organ dysfunction, ultimately traced back to tick-borne infection.5CHEST. Beyond Diseases Case Reports Posters In a pediatric case, a 13-year-old boy was admitted to the ICU with acute renal failure secondary to urinary retention caused by disseminated Lyme disease. The neurological involvement from Lyme disrupted bladder function, and the resulting obstruction led to kidney damage.6Clinical Pediatrics: Open Access. Disseminated Lyme Disease Presenting as Urinary Retention and Acute Renal Failure
That second case is a useful reminder that the kidney damage from Lyme does not always stem from immune-complex deposits. In some situations, Lyme’s effects on the nervous system create a secondary chain of events that ends with the kidneys in trouble. Urinary retention, if left unrecognized, can back up pressure into the kidneys and cause failure quite rapidly.
Treatment When the Kidneys Are Involved
The standard first step is antibiotics to treat the underlying Borrelia infection, typically doxycycline or an intravenous cephalosporin for more severe disease. But when significant kidney inflammation is already underway, antibiotics alone are sometimes not enough. In the two-patient case series mentioned earlier, both patients received corticosteroids alongside antibiotics. The woman with membranoproliferative disease responded well, and the man with flared IgA nephropathy saw his blood and protein in the urine resolve rapidly.3PubMed. Lyme disease-associated glomerulonephritis
A review of six published human cases of post-Borrelia glomerulonephritis found a range of outcomes: three patients responded to antibiotics combined with steroids, one improved with antibiotics plus blood-pressure medication, one required hemodialysis but was able to come off it after five months of aggressive treatment including steroids, plasmapheresis, and intravenous immunoglobulin, and one did not respond and remained on dialysis.7PubMed. Lyme nephritis The fact that most patients improved is encouraging, but the one case of permanent dialysis dependence makes it clear that outcomes depend heavily on how much damage the kidneys have sustained before treatment starts.
The clinical course as well as the final outcome of affected patients may vary depending on the severity of the kidney lesions found on biopsy, a point emphasized in the Journal of Renal Injury Prevention case report.2PubMed Central. Post-infectious glomerulonephritis presenting as acute renal failure in a patient with Lyme disease In practical terms, this means early recognition matters. The sooner the connection between Lyme infection and kidney symptoms is made, the more likely treatment is to preserve kidney function.
Could Lyme Raise Long-Term Kidney Disease Risk?
Beyond the acute cases, there is the question of whether Borrelia exposure leaves a lasting mark on kidney health. A large retrospective cohort study looked at the risk of developing chronic kidney disease (CKD) in patients who had been exposed to Borrelia burgdorferi compared to those who had not. The risk ratio was 1.43, meaning exposed individuals were roughly 43% more likely to develop CKD, a result that was statistically robust.8PubMed. Risk of Development of Chronic Kidney Disease After Exposure to Borrelia burgdorferi and Anaplasma spp. The same study found no increased risk from exposure to Anaplasma, another tick-borne pathogen that often co-infects alongside Borrelia, which strengthens the argument that something specific about Borrelia is driving the kidney risk rather than tick bites in general.
A 43% increase in relative risk sounds alarming, and it is worth putting in context. Chronic kidney disease is common in the general population, driven primarily by diabetes, high blood pressure, and aging. Adding a moderate increase in relative risk from a Lyme infection does not mean every person who has had Lyme should expect kidney problems. It does suggest that people with a history of Lyme disease, especially disseminated or late-stage disease, may benefit from periodic basic kidney screening, something as simple as checking creatinine and looking for protein in the urine during routine bloodwork.
Dogs Get This Much More Often
Much of what we understand about Lyme nephritis originally came from veterinary medicine. Dogs, particularly Labrador retrievers and golden retrievers, develop a well-recognized and often fatal form of Lyme-associated kidney disease known as Lyme nephritis. The condition progresses rapidly in dogs and frequently leads to kidney failure. One study found that increased precipitation (which likely promotes tick activity) was associated with higher odds of dogs developing Lyme nephritis, with each additional inch of rainfall in the three months before diagnosis increasing the odds by about 13%.9PubMed. Precipitation as a Possible Risk Factor for Development of Lyme Nephritis in Dogs
In veterinary practice, the treatment approach for dogs with confirmed or suspected Lyme nephritis is more aggressive than a course of antibiotics alone. The ACVIM consensus statement recommends adding immunosuppressive agents when there is biopsy-confirmed immune-mediated disease, or even without biopsy confirmation in dogs that are not responding to initial treatment or are deteriorating quickly with severe protein loss or rising creatinine.10PubMed Central. ACVIM consensus update on Lyme borreliosis in dogs and cats
The canine model matters for the human question because the underlying mechanism is similar: immune complexes triggered by Borrelia infection deposit in the kidneys and spark inflammation. The reason dogs develop it more often than humans is not fully understood but likely involves differences in immune response, breed-specific genetic susceptibility, and possibly greater cumulative tick exposure. Researchers have explicitly noted that Borrelia is a possible cause of post-infectious glomerulonephritis in humans, just as it is in dogs, and that the relative scarcity of human reports may reflect detection problems more than a true absence of the condition.2PubMed Central. Post-infectious glomerulonephritis presenting as acute renal failure in a patient with Lyme disease
When Lyme Activates a Quiet Kidney Problem
One clinically interesting pattern is Lyme disease unmasking or flaring a kidney condition that was already present but causing no obvious symptoms. The 40-year-old man in the two-case series had a documented history of microscopic hematuria, blood in the urine detectable only by lab testing, that had been sitting quietly for some time. After his tick bite and Lyme infection, that previously silent IgA nephropathy erupted into full-blown proteinuria and gross hematuria.3PubMed. Lyme disease-associated glomerulonephritis
This raises a practical point for anyone with a known kidney condition living in a tick-endemic area. IgA nephropathy, for instance, is one of the most common forms of glomerulonephritis worldwide. Many people carry it with minimal symptoms for years. If a Lyme infection is capable of triggering a flare in those individuals, it adds another reason to take tick-bite prevention seriously and to report a new tick bite to your physician if you have a pre-existing kidney diagnosis. Whether the Lyme infection creates brand-new kidney disease or merely activates something dormant, the clinical result is the same: a patient who needs both anti-infective and kidney-directed treatment.
Signs That Should Prompt a Kidney Workup
Because Lyme nephritis does not come with a unique set of symptoms, it tends to be caught only when someone thinks to look. There are, however, some red flags that should prompt a clinician to check the kidneys in a patient with known or suspected Lyme disease:
- Foamy urine: a sign of excess protein leaking through damaged kidney filters.
- Swelling in the legs or around the eyes: fluid retention from protein loss, suggesting nephrotic-range proteinuria.
- Blood in the urine: visible or detected on a dipstick test, potentially signaling glomerular inflammation.
- Unexplained rise in blood pressure: kidney inflammation can cause sudden hypertension even in people with no prior history.
- Decreased urine output or fatigue: especially when other Lyme symptoms are present, these could point to falling kidney function.
None of these symptoms are specific to Lyme, which is exactly the problem. A simple urinalysis and a basic metabolic panel including creatinine can pick up most of these issues early. If you are being treated for Lyme disease and develop any of the above, flagging it to your doctor is worthwhile. The evidence, limited as it is, consistently shows that earlier recognition of kidney involvement leads to better outcomes.
Nephrotic Syndrome as a Presentation
In its most severe form, Lyme-associated kidney disease can present as full nephrotic syndrome, a cluster of findings that includes massive protein loss in the urine, very low blood albumin levels, high cholesterol, and significant swelling. A case report presented at an American Journal of Kidney Diseases meeting described nephrotic syndrome in a patient with Lyme disease, underscoring that the kidney involvement can occasionally be the dominant clinical problem rather than a footnote to joint or neurological symptoms.11American Journal of Kidney Diseases. 246 Nephrotic Syndrome in patient with Lyme Disease: Case Report The minimal change disease case report mentioned earlier also fell into this category, with the patient presenting with significant proteinuria in the context of chronic Borrelia infection.4PubMed Central. Chronic Lyme borreliosis associated with minimal change glomerular disease: a case report
Nephrotic syndrome from any cause is a medical situation that requires prompt treatment to prevent complications like blood clots, infections, and progressive kidney damage. When Lyme disease is the trigger, the treatment principles overlap: control the infection, dampen the immune response attacking the kidney, and manage fluid and protein loss while the kidney heals. The veterinary experience with dogs, where Lyme nephritis is frequently fatal, serves as a sobering reminder that aggressive early treatment matters. In humans, the published cases suggest most patients recover meaningful kidney function when the infection and inflammation are treated together, but delays can lead to irreversible damage.