- 01The cuff finds it; the lab tests look for why and what it has done
High blood pressure usually causes no symptoms, so a cuff reading, repeated and ideally confirmed at home, is the only way to know. The blood and urine tests that follow a diagnosis are not a measure of blood pressure. They check whether the kidneys are under strain (creatinine, eGFR, urine albumin), look for a hormone cause (primary aldosteronism, which a low potassium can hint at, though most people with it have normal potassium), and add up the other heart risks (blood sugar, cholesterol) that decide how hard care should push.
- 02140/90 means different things on each side of the Atlantic
In the US, 130/80 is the line for high blood pressure and 140/90 is stage 2. UK and European guidelines draw the diagnostic line at 140/90 in the clinic, and the UK uses 135/85 as the home equivalent. A reading of 140/90 is high blood pressure under every current guideline.
- 03One reading is a prompt, not a diagnosis
Blood pressure changes minute to minute. Nerves at the clinic can push a reading up (white coat hypertension), and some people read normal at the clinic but high at home (masked hypertension). Guidelines ask for out-of-office readings to confirm a diagnosis before treatment starts.
High blood pressure, or hypertension, means the pressure of blood pushing on your artery walls stays higher than it should. A reading has two numbers: the top (systolic) number is the pressure while the heart beats, the bottom (diastolic) number is the pressure while it rests between beats. In the US, readings that stay at 130/80 mmHg (millimeters of mercury) or higher count as high blood pressure. 3 About half of American adults have it, and many do not know, because it rarely causes symptoms. 3 The tests that come with a diagnosis are there to find out why the pressure is high and whether it has strained the kidneys or heart. What to do next: if a reading came back high, take home readings the way this guide describes for a week, then bring the log, your latest lab results and this list of questions to your clinician.
Symptoms of high blood pressure
Most people with high blood pressure feel completely normal. The NHLBI puts it plainly: high blood pressure "usually does not cause symptoms until it has also caused serious problems." 4 The signs below are associations to mention to a clinician, not a way to rule it in or out; only a cuff can do that.
- No symptoms at all, the most common picture
- Readings found high at a pharmacy, work check or routine visit
- Headaches are often blamed on blood pressure, but most everyday headaches are not caused by it
- Nosebleeds, which are usually unrelated unless pressure is very high 7
Get care the same day A reading of 180/120 or higher with chest, back or belly pain, trouble breathing, numbness or weakness, a sudden change in vision, trouble speaking or a sudden severe headache: call 911 and do not wait for it to come down. With no symptoms, wait 5 minutes and recheck; if it is still that high, call your clinician right away. 4
Sources: NHLBI high blood pressure symptoms page and the MedlinePlus Medical Encyclopedia.
What is high blood pressure, and who gets it?
Blood pressure is the force your heart uses to push blood through your arteries. It rises and falls through the day with activity, stress, salt, sleep and posture. Hypertension is when it stays high most of the time. Over years, that extra force stiffens and damages artery walls and makes the heart work harder, which is why untreated high blood pressure raises the risk of stroke, heart attack, heart failure, chronic kidney disease, eye damage and aneurysm. 4
Most of the time no single cause is found. MedlinePlus calls this essential hypertension, and it builds from age, genes and habits. 7 Risk is higher with age (arteries stiffen), a family history of high blood pressure, being African American, obesity, diabetes, a high-salt diet, smoking, regular stress and drinking more than 1 drink a day for women or 2 for men. 7 People with type 2 diabetes or metabolic syndrome often have it as one part of a wider picture, and it travels with high cholesterol, which multiplies the heart risk.
When something specific drives the pressure up, doctors call it secondary hypertension. A 2026 commentary on the US guideline notes that it is more common than once assumed, affecting 10% to 35% of adults with hypertension, and that the most common causes are chronic kidney disease, primary aldosteronism, narrowed kidney arteries (renovascular hypertension) and obstructive sleep apnea. 2 MedlinePlus adds adrenal disorders such as Cushing's syndrome and pheochromocytoma, hyperparathyroidism, pregnancy, and medicines including birth control pills, diet pills, some cold and migraine medicines, and corticosteroids. 7
How high blood pressure is diagnosed
A diagnosis rests on readings that stay high across separate occasions, not on one measurement. 7 The 2025 AHA/ACC guideline replaced the 2017 version but kept its categories, with 130/80 as the line for hypertension. 123 When the top and bottom numbers fall in different bands, the higher band counts: 128/84 is stage 1 because of the 84.
| Category (US, NHLBI table) | Top number (systolic) | Bottom number (diastolic) | |
|---|---|---|---|
| Normal | Under 120 | and | Under 80 |
| Elevated | 120 to 129 | and | Under 80 |
| Stage 1 high blood pressure | 130 to 139 | or | 80 to 89 |
| Stage 2 high blood pressure | 140 or higher | or | 90 or higher |
| Hypertensive crisis: contact a clinician immediately, or call 911 with symptoms | Higher than 180 | or | Higher than 120 |
Source for the categories: the NHLBI's table, which follows the US guideline. 3 Outside the US the line sits higher. The 2024 European Society of Cardiology guideline diagnoses hypertension at 140/90 and calls 130 to 139 over 80 to 89 "elevated", and the UK's NICE guideline uses 140/90 in the clinic and 135/85 for the average of home readings. 28
Where an example top number of 142 fallsmmHg (systolic)
140/90, 130/80 or 120/80: what your blood pressure number means
140/90 is the number people search most, and it is high blood pressure under every current guideline. In the US it is the start of stage 2, and in the UK and Europe it is the clinic line for diagnosing hypertension. 238 If 140/90 came from a single reading, the NICE guideline's approach is to take a second reading at the same visit, use the lower of the last two, and confirm with readings outside the clinic. 8
130/80 is stage 1 high blood pressure in the US. 3 For stage 1, the 2025 guideline weighs overall heart risk: medicine is recommended when risk is high, and reasonable when lifestyle change has not brought the number down. 2 The guideline's usual target is under 130/80, with a top number under 120 encouraged where it can be reached safely. 2
120/80 sits on the edge. Normal is under 120/80, and a top number of 120 to 129 with a bottom under 80 is the elevated band, a reason to keep an eye on it rather than a diagnosis. 3 A bottom number of 80 or more on its own counts as stage 1, so 118/82 is stage 1 even though the top number is normal. 3
How to test your blood pressure at home
MedlinePlus notes that readings taken at home may be a better measure of your usual blood pressure than those taken at the clinic, and clinicians use them to spot white coat and masked hypertension. 57 The NHLBI's steps for a reading you can trust: 6
- 1Prepare for 30 minutesNo exercise, meal, caffeine or smoking in the half hour before. If you take blood pressure medicine, measure before the dose. Empty your bladder. 6
- 2Sit right for 5 minutesChair with your back supported, feet flat and uncrossed, in a quiet room. Do not talk or watch TV during the reading. 6
- 3Put the cuff on bare skinUpper arm, above the elbow, not over a sleeve. A cuff that is too small or too big gives a wrong number, so match the cuff to your arm. 56
- 4Support the arm at heart levelRest the arm on a table, palm up, with the cuff level with your heart. 6
- 5Take two or three readingsOne minute apart, at the same time or times each day, and write them all down. 6
Which arm? Check both the first time. NICE's rule is that if the two arms differ by more than 15 mmHg, repeat, and if the gap holds, use the arm with the higher reading from then on. 8 Bring your home monitor to an appointment so it can be checked against the clinic's device. 7 LifeFrom's guide to why trends beat single readings explains why the average of a week matters more than the one number that worried you.
Office reading or home readings: which one confirms high blood pressure
The blood tests and markers to check
None of these tests measures blood pressure. They answer three other questions: has the pressure already strained the kidneys or heart, is a specific cause driving it, and how high is the overall heart risk that decides how hard to treat. The UK's NICE guideline offers every person with hypertension a urine albumin-to-creatinine ratio, a urine dipstick for blood, an A1C, electrolytes, creatinine with eGFR, total and HDL cholesterol, an eye check and an ECG (electrocardiogram, a tracing of the heart's electrical activity). 8 The 2025 US guideline made the urine albumin test routine for everyone newly diagnosed. 2 For the kidney numbers, LifeFrom's kidney function guide explains how creatinine, eGFR and urine albumin fit together, and electrolytes explained covers sodium and potassium.
| Marker | What it shows in high blood pressure | Typical cutoff | First-line or add-on |
|---|---|---|---|
| Creatinine and eGFR | How well the kidneys filter; kidney disease both causes and results from high blood pressure | eGFR under 60 suggests chronic kidney disease 2 | First-line |
| Urine albumin-to-creatinine ratio | Albumin leaking through strained kidney filters; an early sign of damage | 30 mg/g or higher is raised 2 | First-line (routine in the 2025 US guideline) 2 |
| Potassium | Low potassium can hint at primary aldosteronism or a diuretic effect; high potassium can come with kidney disease or some medicines | Below or above your lab's range | First-line |
| Sodium | Blood sodium stays normal with a salty diet; it is checked as a baseline before medicines that can shift it | Your lab's range | First-line |
| Fasting glucose and A1C | Diabetes or prediabetes, which raise heart and kidney risk and change the blood pressure target | A1C 5.7% to 6.4% prediabetes, 6.5% or higher diabetes | First-line 8 |
| Lipid panel, led by LDL cholesterol | The cholesterol side of heart risk, used in the risk estimate | LDL 160 or higher is high | First-line 8 |
| Aldosterone-to-renin ratio | Screens for primary aldosteronism, a hormone cause that has its own treatment | Ratio above about 20 with suppressed renin and an aldosterone of 10 ng/dL or more (immunoassay) 9 | Add-on; the Endocrine Society suggests it for everyone with hypertension 10 |
| TSH | Thyroid hormone signal; a thyroid problem is one of the causes clinicians look for | Your lab's range; a low TSH points to an overactive thyroid | Often included in the first workup; ask whether yours was |
| Uric acid | Can run high with kidney strain, and some diuretics raise it | Above your lab's range | Sometimes added; ask your clinician |
| Hemoglobin | Part of a complete blood count; anemia can come with kidney disease | Your lab's range | Often included in the first workup; ask whether yours was |
| ECG | Thickened heart muscle or rhythm problems from long-standing pressure | Read by a clinician | First-line in NICE 8 |
Estimate your kidney filtration (eGFR)
From your creatinine. Nothing leaves your browser.
If your panel lists creatinine but not eGFR, the tool above and the eGFR calculator turn creatinine, age and sex into an estimated filtration rate. A single eGFR can dip with dehydration or a heavy meat meal, so a low result is usually repeated before it is called kidney disease.
How the markers read together
| Pattern | What it usually means |
|---|---|
| Normal kidney tests, normal potassium, no diabetes, normal cholesterol | Essential hypertension with low added risk; lifestyle change carries more of the plan |
| Low or low-normal potassium, high blood pressure that is hard to control | Primary aldosteronism is worth screening for with aldosterone and renin; a diuretic can also lower potassium |
| Raised urine albumin, eGFR still normal | Early kidney strain; the 2025 guideline treats this as raising risk and favors certain medicine classes 2 |
| eGFR under 60 with raised urine albumin | Chronic kidney disease with high blood pressure, each worsening the other; a lower target is common 2 |
| High A1C or fasting glucose, high triglycerides, low HDL | The metabolic syndrome cluster; overall heart risk is higher than blood pressure alone suggests |
| Low TSH, fast pulse, weight loss, tremor | Possible hyperthyroidism, which raises the top number and is treated at the source |
| High blood pressure with easy bruising, round face, new diabetes, low potassium | Possible Cushing's syndrome; specific cortisol tests sort it out |
| High calcium with high blood pressure | Possible hyperparathyroidism; a parathyroid hormone test is the next step 7 |
Primary aldosteronism: the hormone cause behind a low potassium
Aldosterone is a hormone from the adrenal glands that tells the kidneys to hold on to sodium and let go of potassium. In primary aldosteronism one or both adrenal glands make too much of it on their own, so blood pressure rises and the body's other salt hormone, renin, is switched off. It is estimated to affect about 5% to 10% of people with hypertension and more than 20% of people whose pressure is resistant or difficult to control, and fewer than 3% of eligible patients are ever tested. 9 It matters because it carries more heart and kidney risk than ordinary hypertension and has targeted treatment, either an adrenal operation or a specific medicine. 910
How an aldosterone excess raises blood pressure and can lower potassium
We suggest that all individuals with hypertension be screened for PA by measuring aldosterone and renin and determining the aldosterone to renin ratio, and that subsequent clinical care be guided by the results.Adler GK and colleagues, Primary aldosteronism: an Endocrine Society clinical practice guideline, 2025 10
The 2025 US guideline is narrower: it recommends screening anyone with resistant hypertension, even without low potassium, and screening is considered at stage 2. 29 Practical points from the 2026 review: the test is usually drawn in the morning, seated, without cutting salt beforehand, and most blood pressure medicines can be continued for the first screen, with spironolactone-type medicines (mineralocorticoid receptor antagonists) the main exception. 9 The aldosterone and renin marker pages explain each number.
Conditions that cause or mimic high blood pressure
| Condition | How it overlaps | What tells it apart |
|---|---|---|
| White coat hypertension | High readings only in the clinic | Normal home or 24-hour readings 5 |
| Masked hypertension | Normal in the clinic, high at home or at night | Home or 24-hour readings 5 |
| Primary aldosteronism | Hard-to-control pressure, sometimes low potassium | High aldosterone-to-renin ratio 9 |
| Chronic kidney disease | Both a cause and a result | Low eGFR, raised urine albumin, which come first in the history |
| Obstructive sleep apnea | Snoring, daytime sleepiness, morning headaches, high night readings | A sleep study 2 |
| Hyperthyroidism | Raised top number, fast heart rate | Low TSH with high free T4 or T3 |
| Cushing's syndrome | Hypertension with weight gain, new diabetes, bruising | Cortisol suppression or late-night cortisol tests 7 |
| Medicine or substance effect | NSAID pain relievers, decongestants, birth control pills, corticosteroids, some antidepressants, alcohol, nicotine, stimulants | Pressure falls when the cause is changed with a clinician 7 |
What can help high blood pressure, with the evidence
Lifestyle change is the first step at every stage and the only step for many people with elevated or low-risk stage 1 readings. The 2025 US guideline's lifestyle recommendations: cut sodium below 2,300 mg daily, ideally below 1,500 mg; use a potassium-based salt substitute unless kidney disease or another reason for high potassium rules it out; follow a heart-healthy eating pattern such as DASH (Dietary Approaches to Stop Hypertension); stay physically active; lose at least 5% of body weight if overweight; and avoid alcohol. 2 Each was given the guideline's strongest class of recommendation except salt substitutes. 2
| Approach | What the evidence shows | Strength | Cautions |
|---|---|---|---|
| DASH eating pattern | In the original trial, people with hypertension saw their pressure fall 11.4/5.5 mmHg more than on a typical US diet, with weight and salt held steady 11 | Strong | Rich in potassium; people with kidney disease need their clinician's plan |
| Less sodium | Class I, top-level evidence in the 2025 guideline; below 2,300 mg, ideally 1,500 mg 2 | Strong | Most sodium comes from packaged and restaurant food, not the salt shaker |
| Potassium-based salt substitutes | Recommended by the 2025 guideline for people without kidney disease 2 | Moderate | Not for people with kidney disease or on medicines that raise potassium (some ACE inhibitors, ARBs, spironolactone) 28 |
| Weight loss of 5% or more | Class I recommendation for people with overweight or obesity 2 | Strong | Very fast weight loss needs medical oversight |
| Regular physical activity | Class I recommendation 2 | Strong | Chest pain or breathlessness on exertion needs checking before training |
| Avoiding alcohol | Class I recommendation in the 2025 guideline 2 | Strong | Stopping heavy drinking suddenly can be dangerous; plan it with a clinician |
| Magnesium supplements | A meta-analysis of 34 trials found about 2.0/1.8 mmHg lower readings 12 | Limited | Small effect; NICE says not to use magnesium, calcium or potassium supplements to treat blood pressure; kidney disease raises magnesium risk 8 |
| Omega-3 fish oil | A dose-response meta-analysis of 71 trials found about 2.6/1.6 mmHg lower readings at moderate intakes 13 | Limited | Small effect; can interact with blood thinners |
| CoQ10 | A Cochrane review found moderate-quality evidence of no clinically significant effect on blood pressure 14 | Not supported | Few and small trials |
| Prescription medicines | First-line classes are ACE inhibitors, ARBs (angiotensin receptor blockers), long-acting calcium channel blockers and thiazide-type diuretics; ACE inhibitors or ARBs are preferred with kidney disease or type 2 diabetes 2 | Strong | The choice, combination and target are a clinician's decision |
This review provides moderate-quality evidence that coenzyme Q10 does not have a clinically significant effect on blood pressure.
The size of these effects matters. The DASH diet lowered the top number by more than 11 mmHg in people with hypertension, while magnesium and fish oil move it by about 2 to 3 mmHg. 111213 For someone at 150/95, a supplement alone will not reach a guideline target. The magnesium, omega-3 and CoQ10 guides cover what each compound is and its interactions.
Medicines are named here as facts about how high blood pressure is managed, not as a suggestion for you. Under the 2025 guideline, a single once-daily first-line medicine with close follow-up is one option at stage 1, and resistant hypertension, pressure that stays high on several medicines, prompts a check that the medicines are being taken and a search for causes such as primary aldosteronism. 2 Never stop or change a blood pressure medicine without your clinician: some, stopped suddenly, can make pressure rebound.
Monitoring and retesting
| What | Why | Typical rhythm (your clinician sets it) |
|---|---|---|
| Home blood pressure | Confirms the diagnosis, then shows whether lifestyle or medicine is working | A week of morning and evening readings before visits; two or three readings each time 6 |
| Clinic blood pressure | Checks home readings and the device | At each visit; at least yearly for adults 40 and over 7 |
| Potassium, sodium, creatinine and eGFR | Baseline, then after starting or changing medicines that affect the kidneys or electrolytes | Often within weeks of a change, then yearly |
| Urine albumin-to-creatinine ratio | Tracks kidney strain | At diagnosis, then yearly or as advised 2 |
| A1C or fasting glucose, lipid panel | Overall heart risk | Usually yearly, sooner if borderline |
| Aldosterone and renin | If resistant, stage 2, or low potassium | Once to screen; repeated if equivocal 9 |
When to see a doctor
For everything else, high readings are a reason for a planned appointment within days to weeks, not a crisis. A 180/120 reading without symptoms that stays high on a repeat check needs a call to your clinician right away. 4 Bring a week of home readings, your monitor, your medicine list (including pain relievers, decongestants and supplements) and your latest blood and urine results.
Questions to ask your clinician
- Do my home readings confirm high blood pressure, and which number is my target?
- Have my kidneys been checked with creatinine, eGFR and a urine albumin-to-creatinine ratio?
- Should I be screened for primary aldosteronism with an aldosterone and renin test, given my potassium and my readings?
- Could sleep apnea, a thyroid problem or one of my medicines be raising my pressure?
- What is my overall 10-year heart risk, and does it change whether medicine makes sense now?
- Is a potassium-based salt substitute safe for me?
- Which of my medicines need blood tests after a change, and when?
Heart risk is a whole picture. LifeFrom's heart page brings blood pressure, cholesterol and the related markers together, and if your lipid results came with this, how to read your lipid panel walks through each number. For the blood sugar side, see blood sugar explained.
This guide is general education, not medical advice or a diagnosis. The clinician who knows your history reads your results and makes decisions with you.
This guide is educational only: LifeFrom explains readings and lab results and does not diagnose or treat high blood pressure. A reading of 180/120 or higher with chest, back or belly pain, trouble breathing, numbness or weakness, a change in vision, trouble speaking or a sudden severe headache needs emergency care: call 911 and do not wait to see if it comes down. Without symptoms, recheck after 5 minutes and, if it is still that high, call your clinician right away. During pregnancy or in the weeks after birth, a reading above 160/110 is an emergency. High blood pressure has several possible causes, so find the cause with a clinician before starting anything, and never change a blood pressure medicine on your own.
Citations
- Jones DW, Ferdinand KC, Taler SJ, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults. Hypertension. 2025.
- Kanbay M, Copur S, Sarafidis P, Ferro CJ, Ortiz A. 2025 AHA/ACC guideline for the prevention, detection, evaluation and management of high blood pressure in adults: a commentary from the European Renal Best Practice (ERBP). Nephrol Dial Transplant. 2026;41:1909-1918.
- National Heart, Lung, and Blood Institute (NHLBI). High blood pressure: what is high blood pressure?
- NHLBI. High blood pressure: symptoms.
- NHLBI. High blood pressure: diagnosis.
- NHLBI. Self-measured blood pressure fact sheet (NIH Publication No. 23-HL-8201), May 2023.
- MedlinePlus Medical Encyclopedia. High blood pressure in adults: hypertension. US National Library of Medicine.
- National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management (NG136), recommendations.
- Balhara M, Owei L, Demko J, Wachtel H, Cohen JB. Primary aldosteronism: evaluation and management in the hypertensive patient. Curr Hypertens Rep. 2026;28:47.
- Adler GK, Stowasser M, Correa RR, et al. Primary aldosteronism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2025.
- Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure (DASH). N Engl J Med. 1997;336:1117-1124.
- Zhang X, Li Y, Del Gobbo LC, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension. 2016;68:324-333.
- Zhang X, Ritonja JA, Zhou N, Chen BE, Li X. Omega-3 polyunsaturated fatty acids intake and blood pressure: a dose-response meta-analysis of randomized controlled trials. J Am Heart Assoc. 2022;11:e025071.
- Ho MJ, Li EC, Wright JM. Blood pressure lowering efficacy of coenzyme Q10 for primary hypertension. Cochrane Database Syst Rev. 2016;(3):CD007435.
- NHLBI. High blood pressure: pregnancy and high blood pressure.
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
