Can Parkinson’s Disease Cause Kidney Problems?

Parkinson’s is known as a disease of movement, but it affects the whole body, including the kidneys. People with Parkinson’s do face a higher chance of their kidneys gradually working less well, roughly twice as high in one large analysis, though why isn’t fully understood. Most of the trouble seems to arrive by side routes like the bladder, blood pressure and medicines rather than a direct attack on the kidney. The relationship also runs both ways, because tired kidneys change how some Parkinson’s medicines build up in the body.

How Much Parkinson’s Raises Kidney Risk

People with Parkinson’s were about 1.9 times as likely as people without it to have their kidney function drop significantly over time.¹ That difference held even after accounting for age and other health conditions, so it isn’t explained by Parkinson’s patients simply being older. Doubling a small risk still leaves most people without serious kidney decline, but it does mean kidney checks deserve a regular place in Parkinson’s care.

A significant drop takes years to develop, so the practical value is in catching a trend early, when blood pressure control and medicine adjustments can still slow it. Early decline usually causes no symptoms, which means it shows up first on blood or urine tests. Later signs can include swollen ankles, tiredness and changes in how much you urinate. Those overlap with Parkinson’s fatigue and ageing, so tests matter more than feelings.

When a result is flagged, it often gets rechecked after a few weeks, because dehydration, a recent illness or a hard workout can temporarily distort it. Kidney disease is usually diagnosed when reduced filtering or urine protein persists for about three months, so one odd number is a prompt to retest, not a diagnosis. It helps to ask whether the result is a change from your earlier ones, since the direction over several years tells more than one reading.

Kidney health also affects how long people live. Among people with Parkinson’s, those with chronic kidney disease had about a 24% higher risk of dying over 12 years.² Protein leaking into the urine carried an even higher risk, about 54% greater.³ The worse the kidney function or protein leak, the higher the risk climbed, and women with Parkinson’s and kidney disease were more affected than men.⁴ So a routine urine protein check is worth asking about, not only the blood test.

Why Parkinson’s May Affect the Kidneys

The kidney makes its own dopamine, separate from the brain.⁵ This kidney dopamine helps the body get rid of excess salt and water,⁶ and it calms inflammation and protects kidney tissue from damage.⁷ But whether Parkinson’s reduces kidney dopamine hasn’t been shown. Brain dopamine and kidney dopamine are made separately, so losing the dopamine-making cells in the brain does not automatically mean the kidney’s supply falls. Levodopa is converted to dopamine in the kidney too, which is one reason researchers keep studying the link.

Blood pressure is another candidate. Many people with Parkinson’s have high blood pressure when lying down and drops in pressure when standing.⁸ High night-time pressure can make the kidneys flush out extra salt and water, possibly worsening dizziness the next day.⁹

Both halves of the swing can matter. Standing-up drops mean the kidneys briefly receive less blood flow, and repeated dips can add up to strain on the filters. High pressure while lying down pushes steadily on the small vessels inside the kidneys. Treating one problem can worsen the other, since blood pressure pills taken for lying-down pressure may deepen the standing drops, so doctors weigh the two together. Lying-down high pressure may go unnoticed if blood pressure is only checked sitting in clinic. Home readings lying down and standing can reveal it, and raising the head of the bed is a common suggestion doctors make.

The protein that clumps in Parkinson’s brain cells is also being studied in kidney disease.¹⁰ The best-supported shared processes are worn-out cell energy factories, chemical stress and poor clean-up of cell waste.¹¹ The link may run the other way too, with kidney disease possibly raising Parkinson’s risk.¹² None of these ideas yet changes treatment, but controlling blood pressure helps whichever explanation proves true.

Bladder Problems and the Kidneys

Parkinson’s often disturbs the nerves that control the bladder. Normally the brain tells the bladder when to hold and when to empty, and Parkinson’s disrupts that signalling. The bladder can then contract too early, which produces sudden urgency and the need to go often, including at night. Slowness of movement adds to the problem, because reaching the toilet in time can be hard even when the warning is short.

Urinary complications become more likely the longer and more severe the disease.¹³ Even so, in one group studied, patients who held urine after voiding showed no backup swelling of the kidneys.¹⁴ Serious kidney damage from bladder problems appears uncommon, though leftover urine still raises infection risk and significant retention should be checked.

Retention means urine stays behind after you go, and that matters more for the kidneys. Signs that the bladder is not emptying fully include a weak or slow stream, needing to go again soon after finishing, and dribbling afterwards. Urgency alone does not show retention, because someone can feel constant pressure while the bladder empties normally. A bladder ultrasound after you urinate measures leftover urine and separates the two, which matters because treatment differs. If emptying feels incomplete, ask whether one makes sense.

Some bladder medicines can worsen confusion, so review them with the doctor. Drinking less to avoid trips can strain the kidneys and worsen low blood pressure.

Fever, pain in the side or back, or burning urination can signal an infection reaching the kidneys. These symptoms warrant prompt medical contact rather than waiting.

Parkinson’s Medicines and Kidney Safety

A single dose of levodopa briefly increases kidney filtering and salt loss.¹⁵ Long-term levodopa use did not show the same lasting effect.¹⁶ There is no sign that levodopa damages the kidneys.

Pergolide, an older ergot-based dopamine drug, has rarely caused scar tissue to form around the tubes that drain the kidneys. That scarring can block urine flow and lead to kidney failure needing stents.¹⁷ Pergolide has also been linked to damaged heart valves.¹⁸ The ergot structure is thought to drive this scarring.¹⁹ Pergolide is no longer sold in many countries, including the US, and newer non-ergot drugs are standard.

Cabergoline and bromocriptine share the ergot structure with pergolide, so doctors treat the scarring risk as a class concern even though it is uncommon. Persistent back or flank pain, new leg swelling, breathlessness or passing much less urine should be reported promptly, since they can point to scarring or heart valve trouble. Some doctors order periodic kidney tests or a heart check on these drugs, and it is reasonable to ask what monitoring your prescriber plans. Stopping a Parkinson’s drug suddenly can cause a dangerous worsening, so any change should be planned with the prescriber.

Other medicines matter too. Common painkillers like ibuprofen can harm kidneys with regular use. Many older people with Parkinson’s take several drugs, which raises interaction risk, so bring a full medicine list, including over-the-counter pills, to appointments.

When Kidneys Change How Amantadine Works

Amantadine, used for Parkinson’s movements and stiffness, is cleared almost entirely by the kidneys.²⁰ When the kidneys slow, the drug lingers longer and builds up,²¹ which is why doses must be lowered in kidney impairment.²² Build-up can cause visual hallucinations.²³

Typical early signs are new confusion, vivid hallucinations, agitation, restlessness or disturbed sleep, appearing days to weeks after kidney function dips or a dose rises. Stopping it abruptly can itself worsen symptoms, so call the prescriber for guidance on lowering the dose. A bout of vomiting, diarrhoea or poor drinking can quickly raise levels in someone whose kidneys were already borderline.

Older age, higher doses and higher creatinine were all linked to brain side effects.²⁴ Risk rose sharply at age 77 or older or when kidney clearance fell below 40 mL per minute.²⁵ Ask how your kidney numbers compare before and during amantadine use.

On your lab report, creatinine is a muscle waste product the kidneys clear. The report may also list eGFR, an estimate of how well the kidneys filter, with under 60 signalling reduced function. But low muscle mass, common in frail older people, can make creatinine look falsely reassuring.²⁶ A cystatin C blood test may give a truer picture in thin or frail patients.

Emergencies That Can Damage the Kidneys

Severe involuntary movements, sometimes after too much levodopa, can lead to rhabdomyolysis, a breakdown of muscle that can cause acute kidney failure.²⁷ A sudden fever-and-rigidity syndrome, often after stopping medicine abruptly, can do the same.²⁸

When muscle is damaged, it spills a protein into the blood, and the kidneys struggle to filter it. The protein can block the tiny tubes inside the kidney and is directly toxic to them, so kidney function can fall within a day or two. Dehydration and fever make this worse, which is why fluids are part of the hospital treatment.

Relentless violent or writhing movements that do not settle, especially after a dose change, are a warning sign. A high fever with severe muscle stiffness, sweating, a racing heart and growing confusion points to the fever-and-rigidity syndrome. Dark, tea- or cola-coloured urine suggests muscle protein is reaching the kidneys. Reduced urine output alongside these signs adds to the urgency.

This needs emergency care, not a next-day appointment. Avoid stopping or doubling Parkinson’s doses on your own.

Protecting Your Kidneys With Parkinson’s

Ask for creatinine, eGFR and urine protein at least yearly, more often on amantadine. Track blood pressure lying and standing at home too.

Uric acid is one thing to leave alone. Raising it did not slow Parkinson’s and caused uric acid kidney stones,²⁹ so don’t take supplements to raise it for Parkinson’s.

Steady drinking through the day supports kidney filtering and helps keep blood pressure from dropping when standing. Front-loading drinks in the morning and afternoon and tapering in the evening reduces night-time toilet trips without cutting the total. Constipation is common in Parkinson’s, and enough fluid together with fibre helps, which in turn eases pressure on the bladder. People told to limit fluids for heart or kidney failure should follow their doctor’s target instead.

Different people handle different pieces. The neurologist adjusts Parkinson’s medicines and should know about any kidney result before changing doses, especially for amantadine. A GP is the usual first contact for yearly blood and urine tests, and a referral to a kidney specialist makes sense when the filtering estimate keeps falling over repeated tests. A pharmacist can review the whole list for kidney-sensitive drugs and check that doses are adjusted for your current kidney function.