Polycystic kidney disease: high blood pressure in a young adult

Clinical Rounds, the GPAtlas podcast. Renal. 18 minutes. Published 31 August 2026. Free to listen.

Clinical source: our own Ocean article "Autosomal Dominant Polycystic Kidney Disease (ADPKD)", last reviewed 20 January 2026.

Transcript

Sarah: Hello, and welcome to GPAtlas Clinical Rounds. I'm Sarah, and this is the podcast where we take one thing you'll genuinely see this week, and work out together what to do about it.

Ben: And I'm Ben. I'm the one who's been through the guidance, so when Sarah tells you what she did, I'll tell you whether the evidence agrees with her. Today, high blood pressure, in a young adult.

Sarah: So this is one from my Tuesday morning. She's thirty-four, she's booked in about her pill, and the HCA has left me a blood pressure of a hundred and fifty-two over ninety-six. She feels completely fine. And I've got about four minutes left. Now, I could say look, let's recheck this in a fortnight. Nobody would blame me. Or I could ask her one question. And that question changes the next thirty years of her life.

Ben: So three things today. The question Sarah should ask. The red flags that mean today rather than next week. And the one intervention that's yours, in your room, rather than somebody else's job.

Sarah: Right. So, the question. Young person, blood pressure's up, nothing obvious causing it. Now her own history I've already got, it's on the screen in front of me. What isn't on the screen, and what nobody has ever asked her, is the family. And I don't just mean, any kidney problems. Three things. Kidney disease. Kidney failure of any sort, dialysis, a transplant. And brain aneurysms, or bleeds on the brain. And when I did ask, she told me her dad's on dialysis. She had never once joined those two things up.

Ben: And that question earns its place on the arithmetic. Polycystic kidney disease is common, it runs at fifty-fifty through a family, and the blood pressure is very often the first thing it does, years before the kidneys start to fail. So you're not fishing, Sarah, you're asking the one thing the record can't tell you. What the record can tell you, and it's worth a scroll before you ask anything, is whether there've been water infections that didn't quite add up, or a dipstick with blood on it that got filed and forgotten.

Sarah: So that's the first one. Under forty, blood pressure's up? Ask about the family. And put aneurysms in the question, not just kidneys.

Sarah: Now, the things that can't wait. Because this is a slow disease with some very fast emergencies sitting inside it. And here's the one that has to be automatic for me. Sudden, severe, worst headache of their life, in somebody with polycystic kidneys. That is a bleed until a scan says it isn't.

Ben: And the reason that's not just caution is that these patients genuinely do carry intracranial aneurysms at higher rates than the rest of your list. So a thunderclap headache here is never a migraine, not until somebody has proved it with imaging. And worth saying, that's different from screening. We don't scan everybody's head. Routine aneurysm screening is for those with a family history of a bleed or a known aneurysm, not for everyone with the diagnosis.

Sarah: And then two more that turn up in our world rather than the hospital's. Fever, with bad loin pain. That's an infected cyst, and they behave badly, so that's an admission, not a script for trimethoprim. And sudden severe tummy or flank pain, that's a cyst that's bled or burst.

Sarah: Headache, fever, or sudden pain, in somebody you know has polycystic kidneys. All three of those are same day. Not, come back Thursday.

Sarah: And what do I actually do with her, on Tuesday, in the four minutes I've got left? Because this is the bit that's genuinely mine. The single thing that changes how fast these kidneys fail is the blood pressure. That's it. Below one thirty over eighty. I start an ACE inhibitor or a receptor blocker, and I check her potassium and her kidney function after I've started. And one I have to hold onto with her specifically, because she came in about her pill. Pregnancy, or anyone thinking about it, those two drugs come off, and you're usually switching to labetalol.

Ben: And that is genuinely the highest-value thing anybody does for this patient, which I think surprises people, because it sounds so ordinary. The one people will ask you about is tolvaptan. NICE recommends it in chronic kidney disease stage two or three at the point treatment starts, and only where the disease is progressing rapidly. So that's a referral conversation, it isn't something we're picking up in the room.

Sarah: So in our world, the blood pressure is the whole game.

Sarah: Right. So he's diagnosed, he's on ramipril, and he's coming back to me in a fortnight. What am I actually doing at that visit, and at every one after it? Because this is the bit that isn't dramatic and it's the bit that decides how his forties go. Two weeks after I start the ACE inhibitor, or after any increase, I'm rechecking his U and Es and his potassium. And here's the thing I want to say clearly, because it stops people in their tracks: his eGFR will probably dip a little. That is expected and it is acceptable. A modest fall after starting is not a reason to abandon the drug. If you stop every ACE inhibitor that nudges the creatinine, you will never protect anybody's kidneys.

Ben: And the blood pressure target is worth being precise about, because ADPKD is one of the places we're allowed to be ambitious. The article puts it at under one thirty over eighty as the general aim, and then says a tighter target, around one hundred and ten over seventy-five, may be considered in younger patients with preserved function. He is thirty- two with a normal eGFR. He is exactly that patient. And the reason we reach for an ACE inhibitor or an ARB rather than anything else is that the renin-angiotensin system is central to the hypertension in this disease. It isn't a generic blood pressure problem.

Sarah: The annual review itself is four things, and I find it easier to remember as a set. Blood pressure. U and Es with an eGFR. And an ACR, an albumin to creatinine ratio, because that is how you stage the kidney disease and it's the one people forget. Blood pressure, U and E, eGFR, ACR. Four. And while you're there, a low-salt diet, under six grams a day, and a decent fluid intake unless advanced kidney disease means you have to limit it.

Ben: So the review is four things. And the eGFR dip after starting is expected.

Sarah: Now the traps. And there are a few in this disease that will catch you out on a Friday afternoon. The first one is infection. He rings up, he's got a fever and loin pain, and it looks for all the world like a urinary tract infection. So you do what you always do and you give him nitrofurantoin. And it doesn't touch it.

Ben: Because an infected cyst is not a urinary tract infection. Our article is blunt about it. A cyst infection often will not respond to standard hydrophilic antibiotics, and it names nitrofurantoin and most beta-lactams, because they penetrate cysts poorly. What you need is a lipophilic agent. Ciprofloxacin is the agent of choice, with co-trimoxazole as an alternative. And it makes the point that trimethoprim alone is inadequate for the typical organisms. So the two things most of us would reach for first are the two things that won't work.

Ben: One caveat on the ciprofloxacin, because the MHRA is clear and it applies here. Systemic fluoroquinolones must only be used when other antibiotics are inappropriate, and with special caution over sixty, in renal impairment, or after a transplant, because of tendon injury. So tell the patient to stop and get help at the first sign of tendon, joint, neurological or mood symptoms. This is a specialist-guided situation. You are usually phoning somebody, not just prescribing.

Sarah: Three more, quickly, because they all come up. Pain. Avoid nephrotoxic anti- inflammatories, use paracetamol first. Pregnancy. ACE inhibitors and ARBs are contraindicated and have to be switched before conception or the moment pregnancy is confirmed, to something like labetalol or nifedipine, and you watch for pre-eclampsia. So if you have a woman of childbearing age on ramipril for this, that conversation belongs at the review, not at the positive test. And exercise. Encouraged, genuinely. But avoid contact sports where the kidneys are markedly enlarged, because of the rupture risk.

Ben: And the aneurysm question, which every patient eventually asks, because they have read about it. Screening is not offered universally. Our article lists four situations where you consider an MR angiogram. A family history of aneurysm or subarachnoid haemorrhage. A previous aneurysm. A high-risk occupation. Or before major elective surgery. Outside those, the honest answer is that we don't screen everyone, and that is deliberate rather than neglectful.

Sarah: Nitrofurantoin will not reach a cyst. Ciprofloxacin will.

Ben: There are two pieces of false reassurance in this disease and I want to name both, because they are the reason it gets missed and the reason it gets under-treated. The first is the blood test. Our article says a normal eGFR is not reassuring in ADPKD. Kidney function is typically preserved for decades while the cysts enlarge, so a patient can have massive kidneys and a completely normal eGFR. The number you are looking at is not measuring the thing that is happening.

Ben: The second is your hands. Examination is not a screening tool, and a normal abdomen never excludes it. If you suspect this, you scan. There's a third one worth knowing too, which is the haemoglobin. You'd expect anaemia as kidney disease progresses, and you should check for it, but ADPKD may preserve or even raise the haemoglobin, because the cysts make erythropoietin. So a normal Hb in someone with declining function isn't the reassurance it looks like either.

Sarah: And it's worth saying out loud that this isn't only a kidney disease, because patients find that out from the internet and it's better coming from us. Liver cysts. Diverticular disease. Mitral valve prolapse and aortic regurgitation. Abdominal wall hernias. You're not going to hunt for all of that at every review, but when someone with ADPKD turns up with abdominal pain, or a murmur you hadn't clocked, it should sit differently in your mind.

Sarah: The consultation I find hardest isn't his. It's his sister. She rings up a fortnight later because he's told the family, and she wants to know if she's got it. And the instinct is to order a scan that afternoon. What our article describes is checking her blood pressure and arranging genetic counselling and a nephrology referral, rather than rushing to image. Because a scan result lands on her before anyone has talked to her about what a positive means for insurance, for her job, for whether she has children. That conversation should come first, not as an apology afterwards.

Ben: Two referral triggers to hold on to, and they're the ones people sit on for too long. A declining eGFR, or a blood pressure that won't come to target, goes to nephrology. And an at-risk relative asking to be screened goes to clinical genetics or nephrology, which is exactly the route Sarah just described. On driving, briefly, because he'll ask: for an ordinary licence he may drive and needn't notify the DVLA unless the kidney disorder causes a disability likely to affect his driving. A subarachnoid haemorrhage is different and must be notified.

Sarah: A normal eGFR proves nothing here. Neither does a normal abdomen.

Sarah: Before we do the exam corner, the safety net. Because everything we've said so far is long-game medicine, and there are three moments in this disease where the clock is short and you need to know them cold. The first is the headache. If a patient with ADPKD describes a thunderclap headache, the worst of their life, coming on in seconds, that is a subarachnoid haemorrhage until proven otherwise and it is a nine nine nine call. Not an urgent appointment. Not a same-day review. An ambulance. Their background risk of an aneurysm is higher than the general population's, so the threshold for taking that story seriously has to be lower than your usual one.

Sarah: The second is fever with severe loin pain, which is the infected cyst or pyelonephritis we talked about, and that needs urgent assessment rather than a prescription over the phone. And the third is visible blood in the urine, particularly with clots, or going into retention. That's bleeding into a cyst or into the tract, and it needs urgent review. None of those three is subtle when you know to look for them. All three are easy to soften on the phone at ten to six on a Friday.

Ben: And it's worth putting the whole thing in proportion, which our article does in one line. There is no cure, and only tolvaptan modifies the disease itself, in selected rapidly progressing patients. For everybody else, blood pressure is the cornerstone. That is the treatment. It isn't a holding measure while you wait for something better.

Sarah: Thunderclap headache in ADPKD is an ambulance, not an appointment.

Ben: Right, exam corner. Sarah, and everybody driving, I'll give you a few seconds. Twenty-nine year old man. Blood pressure a hundred and forty-eight over ninety-four, twice. His dad had a kidney transplant at fifty. He's well, takes nothing. Which one of these moves you furthest? A, twenty-four hour blood pressure monitoring. B, a renal ultrasound. C, an urgent CT head looking for aneurysms. Or D, start amlodipine today.

Ben: It's B. The ultrasound. In a young man with that family history, the scan is what actually makes the diagnosis, and the diagnosis changes everything that comes after it. A, the monitoring, isn't wrong, you may well do it, but it confirms a number you've already got twice. C is the trap, and it's the one we just talked about. And D, amlodipine, treats the number and misses the disease.

Sarah: So. Three things for Monday. One. Anybody under forty with high blood pressure gets a family history question, and it covers kidneys, kidney failure, and aneurysms. Two. Thunderclap headache in polycystic kidneys is a bleed until a scan says otherwise. And three, the bit that's yours. Blood pressure under one thirty over eighty, ACE inhibitor or receptor blocker, and check the bloods after you start.

Sarah: One thing to reflect on, if you're logging this. Think about the last young person you started on a blood pressure tablet. Did you ask about their family's kidneys? The full transcript and the references are on the episode page. Ben and I are synthetic voices. The medicine isn't. See you next week.

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