Category: Nephrology · Chronic kidney disease · Screening and nutrition
Found Out About Kidney Disease Only at Stage 3–4? 5 Late Warning Signs, Everyday Eating Habits That Strain the Kidneys, and the eGFR and UACR Tests to Ask For
AI Overview / Quick Answer (BLUF)
Chronic kidney disease stages 3–4 (eGFR 15–59) is often silent because remaining nephrons compensate. Foamy urine, pitting edema, fatigue from anemia, itching and poor appetite tend to appear late. People with diabetes, hypertension, salty diets or regular painkiller use should check eGFR and UACR yearly.
people who have never had kidney tests, or who have just learned they have chronic kidney disease stage 3–4, and want to know which signs to watch, which eating habits speed up decline, and what to test ·
For stage 1–2, read CKD stage 2, fried food and hidden salt ·
Red flags ·
CKD stage table ·
Risky habits table ·
Slowing-decline table ·
FAQ
From a reader comment: why do so many people only learn about kidney decline at stage 3–4, without ever feeling unwell?
Short answer: the kidneys have a large reserve, and kidney symptoms are non-specific. Most people feel normal until eGFR drops below about 30, or until a blood and urine test picks it up by chance.
The only way to find it early is to test, not to wait for symptoms.
A reader asked in the comments why people around them who were newly diagnosed with kidney disease were often already at stage 3–4, and which eating habits are risky without people realizing it.
This article summarizes the evidence to help you watch yourself and your family. It does not replace a diagnosis from a doctor.
Red flags: symptoms that need a doctor now, or emergency services
Short answer: if any of the following occur, especially in someone already known to have kidney disease, do not wait for the next appointment.
Symptoms that should not wait
- Shortness of breath, unable to lie flat, waking up to sit up at night, or rapid whole-body swelling within days — possible fluid in the lungs
- Very little or no urine for more than 12 hours, or visible blood in the urine
- Irregular palpitations, or weakness so severe you cannot lift your arms or legs — possible high blood potassium
- Nausea and vomiting so bad you cannot eat, drowsiness, confusion, muscle twitching or seizures
- Blood pressure of 180/120 or higher with severe headache, chest pain, blurred vision or limb weakness — call emergency services
1. Why kidney decline is silent, and what stage 3–4 means
Short answer: stage 3 is eGFR 30–59 and stage 4 is eGFR 15–29 mL/min/1.73 m², lasting more than 3 months. At this point the remaining nephrons still compensate, so waste levels are not high enough to make you feel ill.
Thai data: common, but rarely known
The Thai SEEK survey (2010)
of 3,459 adults nationwide found a chronic kidney disease prevalence of 17.5%, including about 7.5% at stage 3 and 1.1% at stage 4, yet only 1.9% of participants knew they had kidney disease.
Associated factors included age, diabetes, high blood pressure, high uric acid, a history of kidney stones and traditional medicine use.
In the US, an analysis of NHANES data (2020)
in 3,713 people with stage 3–4 disease found that even in the highest kidney-failure-risk group only 49.0% were aware, and in the low-risk group only 9.6%.
The compensation that hides symptoms
When some nephrons are lost, the remaining ones enlarge and filter harder, so creatinine rises more slowly than the real damage.
But sustained hard filtering gradually wears down the remaining nephrons too. The KDIGO 2024
guideline therefore stages disease by both eGFR and urine albumin (UACR), because albumin leakage often comes before eGFR falls.
The chart shows the eGFR range of each stage for orientation; it does not mean a percentage of kidney function remaining.
Chronic kidney disease stages, eGFR, common symptoms and what to test or do (cards on mobile)
| Stage | eGFR (mL/min/1.73 m²) | Common symptoms | What to test or do |
|---|---|---|---|
| Stage 1–2 | 60 or higher, with signs of kidney damage such as urine albumin | Usually none | UACR, blood pressure and blood sugar at least yearly; cut salt, control blood pressure |
| Stage 3a | 45–59 | Mostly none; some people urinate more at night | eGFR and UACR as scheduled; review every medicine with the doctor; avoid kidney-toxic drugs |
| Stage 3b | 30–44 | Early anemia, tiring easily, harder-to-control blood pressure | Check hemoglobin, calcium, phosphorus and potassium; adjust protein with a dietitian |
| Stage 4 | 15–29 | Swelling, itchy skin, poor appetite, clear anemia, cramps | Shared care with a nephrologist; plan kidney replacement options in advance |
| Stage 5 | Below 15 | Nausea, vomiting, breathlessness from fluid overload, drowsiness, breath odor | Prepare for or start hemodialysis, peritoneal dialysis, transplant, or conservative care |
2. 5 warning signs that tend to appear late, and should prompt testing once noticed
Short answer: these symptoms are not specific to kidney disease and usually become clear at stage 3b–4. If several occur together, or you also have diabetes and high blood pressure, get blood and urine tests rather than waiting for things to get worse.
Sign 1: fine foamy urine that does not settle, or waking at night to urinate more often
Fine foam that lingers for several minutes and recurs for several days may come from albumin leaking into the urine, but foam also comes from a forceful stream or concentrated urine, so looking cannot confirm it; a UACR test is needed.
Waking to urinate more often at night happens when the kidneys concentrate urine less well, but it is also common with an enlarged prostate or drinking before bed.
Sign 2: pitting swelling at the ankles or shins, or puffy eyelids in the morning
When the kidneys excrete less salt and water, or lose a lot of albumin in the urine, fluid builds up in the tissues. Press on your shin for 5 seconds; if a dent remains after you let go, there is fluid retention.
Swelling can also come from heart, liver or vein disease or certain medicines, so a doctor should look for the cause.
Sign 3: fatigue, getting tired easily and pale skin from anemia
The kidneys make the hormone erythropoietin (EPO), which tells the bone marrow to produce red blood cells; as kidneys decline, this hormone falls.
NHANES data (2014)
found anemia in 15.4% of people with kidney disease versus 7.6% of the general population, rising from 8.4% at stage 1 to 53.4% at stage 5.
A meta-analysis of 449 studies (2022)
found fatigue in about 70% of people with kidney disease not on dialysis.
Sign 4: dry skin, itching without a rash, or frequent cramps
Kidney-related itching has several mechanisms, including retained waste, immune changes and mineral imbalance such as abnormal phosphorus and calcium; it is more common at stage 4–5 than stage 3.
Cramps may relate to electrolyte changes or diuretics. Itching and cramps often have other causes, so they are supporting signs, not diagnostic ones.
Sign 5: poor appetite, nausea, a metallic taste or breath odor
When eGFR is very low, waste from protein metabolism builds up in the blood, causing nausea, poor appetite, altered taste and ammonia-like breath.
This cluster usually signals late stage 4 to stage 5. If you have these symptoms, see a doctor soon rather than waiting for an annual check-up.
Not having any of these 5 signs does not mean your kidneys are normal. Most people with stage 3 disease have no symptoms at all, and all 5 signs can come from other conditions. That is why eGFR and UACR testing matter more than guessing from symptoms.
Do your kidney-related symptoms, or a family member’s, fit the warning signs — how serious are they, and when should you not wait?
Get a severity analysis and personalized guidance from our Advisory team — the score helps you see whether swelling, urine changes, blood pressure, fatigue or other kidney-related symptoms match the warning signs, which level they fall into, and when to see a doctor urgently. Use it alongside the red-flag section above; it is not a diagnosis.
3. Eating and medicine habits that speed up kidney decline without people noticing
Short answer: the accelerators with clear evidence are total daily salt, sugar that leads to diabetes, more protein than needed, and high-dose painkillers or herbal products of unknown content. Drinking too little water is a problem when it reaches dehydration.
Hidden salt in fish sauce, seasoning powder, instant noodles, soups and processed food
The CRIC study (2016)
followed 3,939 people with chronic kidney disease and found those with the highest urinary sodium had a 1.54-fold higher risk of faster kidney decline than the lowest group.
A Cochrane review (2021)
found cutting salt by about 4.2 grams per day lowered blood pressure by an average of 6.9/3.9 mmHg and urine albumin by 36% (the albumin data come mainly from earlier-stage CKD). KDIGO 2024 recommends no more than 2 grams of sodium per day, or about 5 grams of salt, across all meals.
Very sweet food, soda, milk tea and uncontrolled diabetes
A 2017 review
reports that diabetic kidney disease develops in about 40% of people with diabetes and is the leading cause of chronic kidney disease worldwide, progressing from hyperfiltration to albumin leakage and then eGFR decline.
A study of 3,003 adults (2019)
found a beverage pattern high in soda and sweetened fruit drinks was associated with 1.61-fold higher odds of new kidney disease. This is observational and shows association, not proof of direct cause.
More protein than needed, such as large portions of meat at every meal or several scoops of whey a day
A Korean community study of 9,226 people (2020)
found the highest protein intake group had a 3.48-fold higher risk of renal hyperfiltration than the lowest, and a 1.32-fold higher risk of rapid eGFR decline.
For people with normal kidneys, it is not yet clear that high protein causes harm, but for people with stage 3–4 disease KDIGO 2024 suggests about 0.8 grams of protein per kilogram of body weight per day.
Cutting protein on your own until you lose weight and muscle is also dangerous; plan with a dietitian.
High-dose NSAID painkillers, unregistered herbal pills, herbs and supplements of unknown content
A 2013 systematic review
found high-dose NSAID painkillers such as ibuprofen, naproxen and diclofenac were associated with a 1.26-fold higher risk of faster kidney decline, while regular doses showed no clear risk.
These drugs reduce blood flow to the kidneys, so they are more dangerous combined with diuretics, ACE inhibitors or ARBs, or during dehydration.
The Thai SEEK survey found traditional medicine use was associated with chronic kidney disease. Unregistered herbal pills or products may be contaminated with heavy metals, steroids or kidney-toxic substances.
Drinking so little you become dehydrated: a real problem, but drinking extra does not restore kidneys
Dehydration from diarrhea, vomiting or working in the heat can cause acute kidney injury on top of chronic disease. But
the CKD WIT trial (2018)
in 631 people with stage 3 disease found drinking about 0.6 liters more per day did not slow eGFR decline over 1 year (a difference of only 0.3 mL/min/1.73 m²).
Drink enough to keep urine pale yellow; people with stage 4 disease who have swelling or a weak heart may need to limit fluids as their doctor advises.
Risky habits, how they affect the kidneys, and kidney-friendly alternatives (cards on mobile)
| Risky habit | How it harms the kidneys | Kidney-friendly alternative |
|---|---|---|
| Hidden salt: fish sauce, soy sauce, seasoning powder, instant noodles, soups, pickles | Higher blood pressure, more albumin leakage, and albumin-lowering drugs work less well | No more than 2 g sodium a day; taste before seasoning; leave the soup; use lime, garlic, pepper and herbs instead |
| Very sweet food, soda, milk tea and uncontrolled diabetes | High glucose drives hyperfiltration, scarring and weight gain | Water, unsweetened tea or coffee; reduce sweetness step by step; keep HbA1c at the doctor’s target |
| More protein than needed: large meat portions every meal, several whey scoops | Raises pressure and filtration in the remaining nephrons | Stage 3–4: about 0.8 g/kg/day; choose fish, eggs, tofu, legumes; plan with a dietitian |
| High-dose or long-term NSAID painkillers | Reduces kidney blood flow; risk of acute kidney injury | Ask a pharmacist about alternatives, such as paracetamol at an appropriate dose |
| Unregistered herbal pills, herbs, supplements of unknown content | May contain heavy metals, steroids or kidney toxins | Tell your doctor about every product; use only registered products your doctor considers safe |
| Drinking so little you become dehydrated | Less blood flow to the kidneys, worsening existing decline | Drink enough for pale yellow urine; at stage 4 with swelling, limit fluids as advised |
4. What to test to catch it early: eGFR, UACR and who should be tested
Short answer: there are two key tests — a blood creatinine test to calculate eGFR and a urine albumin-to-creatinine ratio (UACR). Both are inexpensive and can reveal disease years before symptoms.
Groups who should be tested at least once a year
- People with diabetes or high blood pressure
- People with heart disease or stroke
- A family member with kidney disease or on dialysis
- Past kidney stones, or high uric acid
- Regular use of painkillers, herbal pills or herbal products
- Age 60 or older, or albumin found in the urine before
How to read the results at a glance
A UACR below 30 mg/g is normal, 30–300 is moderately increased albumin, and above 300 is severely increased. A single abnormal value must be repeated, because hard exercise, fever or a urinary tract infection can raise it temporarily.
The KDIGO Controversies Conference (2021)
concluded that screening at-risk groups with eGFR and UACR is worthwhile, because medicines that genuinely slow kidney decline are now available when started early.
Comparison of approaches to slow kidney decline at stage 3–4: medicines (drug classes), dietary changes, natural options and behaviors (cards on mobile)
| Approach | Kidney effect | Evidence | Cautions |
|---|---|---|---|
| ACE inhibitors or ARBs | Lower blood pressure and urine albumin; slow decline | KDIGO 2024 recommends them when albuminuria occurs with high blood pressure or diabetes | Check potassium and kidney function after starting; beware potassium-based salt substitutes |
| SGLT2 inhibitors | Slow decline with or without diabetes | EMPA-KIDNEY: 6,609 patients; primary outcome 16.9% to 13.1% (HR 0.72) | Use as indicated by the doctor; watch for dehydration and urinary tract infection |
| Cutting total daily salt | Systolic pressure down 6.9 mmHg on average; urine albumin down 36% (mainly earlier-stage CKD) | Cochrane 2021 and CRIC 2016 | People on several blood pressure drugs may feel dizzy from low pressure |
| Right-sized protein with a dietitian | Reduces filtration load on the remaining nephrons | KDIGO 2024: stage 3–5 about 0.8 g/kg/day | Older adults risk malnutrition if they cut protein on their own |
| “Kidney tonic” herbs or supplements (natural option) | No evidence they restore kidney function | Thai SEEK found traditional medicine use associated with chronic kidney disease | Some are kidney-toxic or high in potassium; tell your doctor before use |
| Drinking more water than usual | Did not slow eGFR decline over 1 year | CKD WIT: 631 patients, difference 0.3 mL/min/1.73 m² (not significant) | Stage 4 with swelling or a weak heart may require fluid limits |
| Avoiding high-dose NSAID painkillers | Lowers risk of faster decline and acute kidney injury | 2013 systematic review: high dose 1.26-fold risk | Ask a pharmacist or doctor about alternative pain relief |
Frequently asked questions (FAQ)
Common questions about chronic kidney disease stages 3–4, warning signs and risky habits
Why can kidney disease reach stage 3–4 without symptoms?
Healthy nephrons work harder to compensate for the ones that are lost, so waste levels in the blood stay too low to cause symptoms. Clear symptoms usually start when eGFR falls below about 30. The Thai SEEK survey found chronic kidney disease in 17.5% of Thai adults, yet only 1.9% knew they had it. Having no symptoms does not mean the kidneys are normal.
Does foamy urine always mean kidney damage?
No. Foam can come from a forceful stream, concentrated urine when you drink little, or cleaning products in the toilet. The foam worth checking is fine foam that does not settle after several minutes and appears for several days in a row, especially with diabetes, high blood pressure or swelling. The way to confirm is a UACR test, not looking at it.
What eGFR counts as kidney disease stage 3 and stage 4?
Under the KDIGO 2024 guideline, stage 3a is eGFR 45–59, stage 3b is 30–44 and stage 4 is 15–29 mL/min/1.73 m², lasting more than 3 months. A single low value can come from dehydration or an acute illness, so it must be repeated, and urine albumin (UACR) is needed alongside it to judge risk.
Who should get kidney tests, and how often?
People with diabetes, high blood pressure, heart disease, a family history of kidney disease, past kidney stones, regular use of painkillers or herbal products, or older age should have creatinine for eGFR and a UACR test at least once a year. If results are abnormal, the doctor will repeat them more often according to stage and albumin level.
Can drinking lots of water restore kidney function?
No. In the CKD WIT trial of 631 people with stage 3 kidney disease, one group drank about 0.6 liters more water per day, and after 1 year their eGFR declined no differently from the usual-intake group. What to avoid is dehydration from diarrhea, vomiting or working in the heat. People with stage 4 disease and swelling may need to limit fluids as their doctor advises.
Does eating a lot of protein or whey harm the kidneys?
In people with normal kidneys the evidence is unclear, but a Korean study of 9,226 people found the highest protein intake group had a 3.48-fold higher risk of renal hyperfiltration and a 1.32-fold higher risk of rapid eGFR decline. For people with stage 3–4 kidney disease, KDIGO suggests about 0.8 grams of protein per kilogram of body weight per day. Do not cut protein on your own to the point of malnutrition; plan with a dietitian.
How risky are regular painkillers or herbal products for the kidneys?
A 2013 systematic review found high-dose NSAID painkillers were associated with a 1.26-fold higher risk of faster kidney decline, while regular doses showed no clear risk. The Thai SEEK survey found traditional medicine use was one of the factors associated with chronic kidney disease. People with kidney disease should tell their doctor or pharmacist before using any painkiller, herbal product or supplement.
Can stage 3–4 kidney disease be reversed, or how much can it be slowed?
Scarred nephrons usually do not recover, but decline can be slowed considerably. Controlling blood pressure, blood sugar and urine albumin, cutting salt, and kidney-protective medicines when a doctor finds them suitable all slow progression. For example, the EMPA-KIDNEY trial of 6,609 patients found SGLT2 inhibitors reduced kidney progression or cardiovascular death from 16.9% to 13.1%.
Scientific mechanism in brief
Summarized by Asst. Prof. Dr. Norawit Raatpiboon:
each kidney contains several hundred thousand to about a million nephrons. When some are lost to diabetes, high blood pressure or toxins, the rest enlarge and raise the pressure in their glomerular capillaries to maintain total filtration, so creatinine looks nearly normal.
But sustained high pressure makes the filter leak; leaked albumin triggers inflammation and scarring in the kidney tissue, and more nephrons are lost in a cycle. Excess salt, sugar and protein all raise this pressure, while NSAID painkillers block the prostaglandins that keep kidney blood vessels open.
Once eGFR falls below about 30, the kidneys make too little EPO, causing anemia; cannot excrete salt and water fast enough, causing swelling; lose control of phosphorus and calcium, contributing to itching; and retain protein waste, causing nausea. Symptoms therefore arrive after much of the damage has already occurred.
Academic citations (E-E-A-T)
- KDIGO CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int 2024.
- Ingsathit A, et al. Prevalence and risk factors of chronic kidney disease in the Thai adult population: Thai SEEK study. Nephrol Dial Transplant 2010.
- Chu CD, et al. CKD Awareness Among US Adults by Future Risk of Kidney Failure. Am J Kidney Dis 2020.
- Fletcher BR, et al. Symptom burden and health-related quality of life in chronic kidney disease: a global systematic review and meta-analysis. PLoS Med 2022.
- Stauffer ME, Fan T. Prevalence of anemia in chronic kidney disease in the United States. PLoS One 2014.
- Alicic RZ, Rooney MT, Tuttle KR. Diabetic Kidney Disease: Challenges, Progress, and Possibilities. Clin J Am Soc Nephrol 2017.
- He J, et al. Urinary sodium and potassium excretion and CKD progression. J Am Soc Nephrol 2016.
- McMahon EJ, et al. Altered dietary salt intake for people with chronic kidney disease. Cochrane Database Syst Rev 2021.
- Jhee JH, et al. High-protein diet with renal hyperfiltration is associated with rapid decline rate of renal function: a community-based prospective cohort study. Nephrol Dial Transplant 2020.
- Rebholz CM, et al. Patterns of Beverages Consumed and Risk of Incident Kidney Disease. Clin J Am Soc Nephrol 2019.
- Nderitu P, et al. Non-steroidal anti-inflammatory drugs and chronic kidney disease progression: a systematic review. Fam Pract 2013.
- Clark WF, et al. Effect of Coaching to Increase Water Intake on Kidney Function Decline in Adults With Chronic Kidney Disease: The CKD WIT Randomized Clinical Trial. JAMA 2018.
- Shlipak MG, et al. The case for early identification and intervention of chronic kidney disease: conclusions from a KDIGO Controversies Conference. Kidney Int 2021.
- The EMPA-KIDNEY Collaborative Group. Empagliflozin in patients with chronic kidney disease. N Engl J Med 2023.
Compiled and reviewed by Asst. Prof. Dr. Norawit Raatpiboon · Generic and drug-class names only; no trade names of medicines or products.
Medical disclaimer
This article is educational information based on research and international guidelines. It is not a diagnosis, not a treatment order, and does not replace advice from your doctor or dietitian. The symptoms described can come from other conditions, and having no symptoms does not mean your kidneys are normal. The right amounts of salt, protein, fluid and potassium differ by disease stage, medicines and individual blood results. Do not stop or change medicines on your own. If you have shortness of breath, rapid swelling, very little urine, irregular palpitations, or drowsiness and confusion, see a doctor immediately or call emergency services.