eGFR Dropped From 89 to 73 in a Year: Is It Kidney Disease, How Much Do Salty Sauces, Soda and Processed Meat Matter, Does 3 Liters of Water Help, and Which Tests to Repeat

A question from a health group: no alcohol, no smoking, but eGFR fell from 89 to 73 — after quitting salty and sweet food and drinking 3 liters of water, will kidney numbers improve?

Short answer: stopping these habits is the right direction, but before concluding the kidneys are failing, confirm the drop is real. What helps the kidneys most is cutting salt and controlling blood pressure and blood sugar, more than drinking large amounts of water.

A Facebook user in a health group shared that last year’s check-up showed an eGFR of 89 and this year’s showed 73. He did not drink alcohol or smoke, but often ate 5–6 bowls of grilled-pork dipping sauce at a time, drank soda and ate bakery items every day, ate meatballs, pork roll and Chinese sausage, finished every bowl of noodle soup and drank very little water. He has now stopped all of these and drinks 3 liters of water a day. This article summarizes what that eGFR means, which habits really affect the kidneys, how much 3 liters of water helps, and how to repeat testing. It does not assess any individual case and does not replace advice from your own doctor.

1. What an eGFR of 73 means, and whether it is stage 2 kidney disease

Short answer: an eGFR of 73 alone is not chronic kidney disease. Signs of kidney damage must also be present for more than 3 months. But a 16-point drop in one year is much faster than aging, so repeat the test rather than ignoring it.

What eGFR is

eGFR (estimated glomerular filtration rate) is kidney filtration calculated from blood creatinine, age and sex; it is not measured directly. The current equation is CKD-EPI 2021, which no longer uses race (Inker 2021). When labs use different equations or creatinine methods, year-to-year results cannot always be compared directly.

The KDIGO 2024 definition of chronic kidney disease

The KDIGO 2024 guideline defines chronic kidney disease as abnormal kidney structure or function lasting more than 3 months: an eGFR below 60, or signs of kidney damage such as a urine albumin-to-creatinine ratio (UACR) of 30 mg/g or more, abnormal urine sediment or abnormal kidney imaging. An eGFR of 60–89 with no other signs falls in the G2 range, common in the general population and especially with age, and is not “stage 2 kidney disease”.

Is this drop real or just variation?

In stable patients (Waikar 2018), creatinine varied naturally by about 5.4%, and needed to rise more than about 16% or fall more than about 14% to count as a real change. An 18% eGFR drop is borderline: slightly beyond normal variation but short of KDIGO’s 25% threshold for a certain decline. A systematic review of 129,359 healthy adults (Guppy 2024) found age-related decline of about 0.37–1.07 points per year in people without hypertension, so a 16-point drop in one year should not be dismissed as aging.

Table interpreting eGFR together with urine albumin according to KDIGO, to help understand results, not to diagnose (shown as cards on mobile).

2. Why eGFR can fall even when the kidneys may not be damaged

Short answer: eGFR reflects blood creatinine. Anything that raises creatinine without involving the kidneys can make eGFR look lower.

Cooked meat before the blood test

Meat contains creatine, which turns into creatinine with heat. In a study of 80 people (Nair 2014), one cooked meat meal raised creatinine and lowered eGFR significantly within 1–4 hours in every group; 6 of 16 people with stage 3a kidney disease were misclassified as stage 3b, and the effect disappeared after 12 hours of fasting. A big grilled-pork or steak dinner the night before can make results look worse than reality.

Drinking too little or sweating heavily

Dehydration temporarily reduces blood flow to the kidneys, so creatinine rises. This reverses with enough fluid, but it does not mean that drinking more and more increases filtration.

Muscle, exercise and the lab

Creatinine comes from muscle. People who gain muscle, exercise hard the day before testing or take creatine supplements may show a lower eGFR without kidney damage. Testing at a different hospital or with a different method can also change results. In these cases cystatin C, which does not depend on muscle, helps confirm results. A study (Inker 2012) found the combined creatinine and cystatin C equation was more accurate and reclassified 16.9% of people with a creatinine-based eGFR of 45–59 as 60 or higher.

Medicines to review

Regular NSAID painkillers such as ibuprofen, naproxen and diclofenac genuinely reduce kidney blood flow, while some medicines such as trimethoprim or cimetidine raise creatinine without truly reducing filtration. Bring a full list of medicines and supplements to your doctor when you retest.

3. How much the described eating habits affect the kidneys, according to evidence

Short answer: salt has the clearest evidence, followed by processed food and sugary drinks. The idea that uric acid destroys the kidneys is not supported by trials.

Dipping sauces, fish sauce and soup: salt is the main issue

Dipping sauces, chili fish sauce and soup are major salt sources in Thai food. Excess salt makes the body retain fluid, raises blood pressure and increases pressure inside the kidney filters, so more albumin leaks into the urine. KDIGO 2024 recommends that people with kidney disease eat no more than about 2 g of sodium a day, or about 5 g of salt.

The evidence on salt and the kidneys

Among 3,939 people with kidney disease (He 2016), those with the highest urine sodium had 1.54 times the risk of kidney worsening compared with the lowest. A Cochrane review (McMahon 2021) of 21 studies and 1,197 people found that cutting salt by about 4.2 g a day lowered blood pressure by 6.91/3.91 mm Hg and urine albumin by 36%. In a crossover trial (McMahon 2013), salt restriction lowered blood pressure by an average of 10/4 mm Hg.

Soda, bakery items and sweets

In a community study of 3,003 people (Rebholz 2019), a drinking pattern high in soda and sweetened fruit drinks was linked with 1.61 times the odds of kidney disease. Another study in women (Lin 2011) found no association with sugar-sweetened soda, but drinking 2 or more diet sodas a day was linked with 2.02 times the odds of faster kidney decline. The evidence is observational and inconsistent, but cutting sugary drinks improves weight, blood pressure and blood sugar, which are clear kidney risk factors.

Meatballs, pork roll and Chinese sausage: salt and added phosphate

Processed meat is high in salt and contains phosphate added as a preservative. Inorganic phosphate from additives is absorbed much more readily than natural phosphorus (Kalantar-Zadeh 2010) and often does not appear on nutrition labels. Phosphorus is mainly a problem once the kidneys are impaired; healthy kidneys excrete the excess. A study of 14,679 people followed for 24 years (Du 2022) found the highest ultra-processed food intake was linked with 24% higher kidney disease risk, and swapping 1 serving of ultra-processed food for minimally processed food lowered risk by 6%.

Grilled pork and animal protein

In 1,624 women (Knight 2003), high protein intake was not linked with decline in those with normal kidney function, but in those with an eGFR of 55–80 every extra 10 g of protein was linked with an eGFR drop of 1.69 points over 11 years, and non-dairy animal protein with a drop of 1.21 points. People with an eGFR of 60–89 should eat meat in moderation rather than cutting it out, and add plant protein such as beans and tofu.

Does uric acid really damage the kidneys?

High uric acid often accompanies kidney disease, but two large randomized trials found lowering it did not slow kidney decline: in 363 people with stage 3–4 kidney disease (Badve 2020) and 530 people with type 1 diabetes (Doria 2020) given allopurinol. Claiming that “sugar makes uric acid crystallize in the kidneys and destroys them” goes beyond the evidence.

Table summarizing the reader’s eating habits, related substances, mechanisms and strength of evidence, without trade names (shown as cards on mobile).

4. Does drinking 3 liters of water a day really improve eGFR?

Short answer: it helps if eGFR was low because of dehydration, but drinking beyond your needs does not improve filtration, and a randomized trial in people with kidney disease found it did not slow decline.

The evidence on drinking water

The CKD WIT trial (Clark 2018) coached one group of 631 people with stage 3 kidney disease to drink more, raising urine output by about 0.6 liters a day. After one year eGFR fell by 2.2 points with extra water and 1.9 points with usual intake, with no difference. An observational study of 2,148 people (Clark 2011) found that people with more urine had slower eGFR decline (1.3% vs 0.5% per year), but this type of study cannot prove cause and effect.

How much water to drink

For most people without restrictions, drink to thirst until urine is pale yellow, usually about 1.5–2.5 liters a day, more in hot weather or with heavy sweating. Drinking 3 liters is usually not harmful with healthy kidneys but adds no benefit, and avoid drinking very large amounts quickly, such as more than 1 liter per hour, because it can lower blood sodium.

Who should not force large amounts of water

• People with heart failure, cirrhosis or fluid retention
• People with advanced kidney disease or on dialysis whose doctor limits fluid
• People with past low blood sodium or taking certain diuretics

4 steps for kidney care after quitting risky habits

5. How to repeat testing for reliable results

Short answer: prepare the same way each time, use the same lab and add a urine test, because urine albumin predicts risk better than eGFR alone.

Before the blood test

• Avoid a large meat meal, such as grilled pork or steak, for at least 12 hours before the blood draw
• Avoid hard exercise for 1–2 days before testing, and pause creatine supplements as your doctor advises
• Drink normally; there is no need to drink extra before testing
• Test at the same lab and bring last year’s results to compare

Tests to ask for

Creatinine with eGFR, cystatin C if available (KDIGO 2024 recommends it to confirm results when creatinine may be inaccurate), a urine albumin-to-creatinine ratio (UACR) from a first-morning sample, a routine urine test for blood or sediment, blood pressure, blood sugar or HbA1c and blood lipids. UACR can vary by about 30% from day to day (Waikar 2018), so it usually needs to be abnormal in 2 of 3 samples to confirm.

How to read the repeat results

If eGFR returns close to the previous value with no albumin, it was most likely variation or a temporary factor; follow up yearly. If eGFR stays around 70 without albumin, watch the trend and control risk factors. If albumin is present or eGFR keeps falling, a doctor will look for causes such as high blood pressure, diabetes, kidney stones or kidney inflammation and plan kidney protection.

6. Comparing kidney care options when eGFR falls

Short answer: the clearest evidence supports cutting salt, controlling blood pressure and blood sugar, and a healthy eating pattern. Drinking far beyond your needs, uric acid-lowering medicine and kidney supplements have no evidence of slowing decline. This table uses drug classes only.

Treatment comparison table

Comparison of diet changes, water intake, medicines and supplements when eGFR falls (shown as cards on mobile).

Frequently asked questions (FAQ)

Questions readers often ask when a check-up eGFR falls.

My eGFR dropped from 89 to 73 in one year. Does that mean I have stage 2 kidney disease?

Not from one value. Under KDIGO 2024, chronic kidney disease requires an eGFR below 60 or signs of kidney damage, such as urine albumin of 30 mg/g or more, lasting longer than 3 months. An eGFR of 73 without other signs falls in the G2 range, which is common in the general population and older adults. However, a 16-point drop in one year is faster than age-related decline of about 0.37–1.07 points per year, so repeat the test with a urine check rather than ignoring it.

I don’t drink alcohol or smoke. Why did my eGFR still drop?

eGFR is calculated from blood creatinine, so it can change for reasons other than kidney damage: eating cooked meat before the blood test, drinking too little or sweating heavily, hard exercise or more muscle, some medicines, and testing at a different lab or with a different equation. Creatinine naturally varies by about 5.4%, and a rise above roughly 16% starts to count as a real change. Risk factors more common than alcohol or smoking are high blood pressure, diabetes, excess weight, regular NSAID painkiller use and very salty food.

Can eating grilled pork or other meat before a blood test really lower eGFR?

Yes. Meat contains creatine, which turns into creatinine when cooked and is absorbed into the blood. In a study where volunteers ate a cooked meat meal, creatinine rose and eGFR fell significantly within 1–4 hours in every group; 6 of 16 people with stage 3a kidney disease were misclassified as stage 3b, and the effect disappeared after 12 hours of fasting. Before a repeat test, avoid a large meat meal the night before.

How do dipping sauces, noodle soup and processed meat affect the kidneys?

Dipping sauces, fish sauce, soup and processed meat are major salt sources in Thai food. Too much salt raises blood pressure and urine albumin. Among 3,939 people with kidney disease, those excreting the most sodium had 1.54 times the risk of kidney worsening, and cutting salt by about 4.2 g a day lowered blood pressure by 6.91/3.91 mm Hg and urine albumin by 36%. Processed food also contains added phosphate, which is absorbed more easily than natural phosphorus, and the highest intake of ultra-processed food was linked with 24% higher kidney disease risk. Aim for no more than about 2 g of sodium a day.

Do soda and sweets damage the kidneys through uric acid?

Sugary drinks are linked with kidney disease risk, but there is no evidence that this works directly through uric acid. One study found a drinking pattern high in soda and sweetened fruit drinks had 1.61 times the odds of kidney disease, while another found risk in people drinking 2 or more diet sodas a day. Two large trials of lowering uric acid with allopurinol did not slow kidney decline. The benefit of cutting sugary drinks probably comes from better weight, blood pressure and blood sugar, and switching to large amounts of diet soda is not the answer.

Will drinking 3 liters of water a day bring my eGFR back up?

If eGFR fell because of dehydration, drinking enough water can bring it back up, but drinking beyond your needs does not increase kidney filtration. In a randomized trial of 631 people with stage 3 kidney disease, those coached to drink more, raising urine output by about 0.6 liters a day, had an eGFR decline of 2.2 vs 1.9 points over one year, with no difference. For most people without restrictions, drink to thirst until urine is pale yellow rather than forcing 3 liters; people with heart failure, cirrhosis or advanced kidney disease should ask their doctor first.

When should I repeat the test, and what should be checked besides eGFR?

Repeat within about 1–3 months, or sooner if you have symptoms. Use the same lab, avoid a large meat meal for 12 hours before the blood draw, avoid hard exercise for 1–2 days and drink normally. Ask for creatinine with eGFR, cystatin C if available, a urine albumin-to-creatinine ratio (UACR), which should be repeated because it varies a lot, a routine urine test, blood pressure, blood sugar or HbA1c and lipids. An abnormality must last longer than 3 months to be called chronic kidney disease.

If repeat testing confirms chronic kidney disease, can it still be slowed?

Yes, especially when found while eGFR is still high. Proven steps are controlling blood pressure and blood sugar, cutting salt, losing excess weight, quitting smoking, avoiding over-the-counter NSAID painkillers and eating a Mediterranean or DASH-style diet, which in people with kidney disease was linked with 25% lower risk of kidney worsening. With urine albumin or diabetes, a doctor may consider ACE inhibitor or ARB medicines and SGLT2 inhibitor medicines, which protect the kidneys. Regular follow-up matters more than kidney supplements.

Scientific mechanism

Summary by Asst. Prof. Dr. Norawit Raatpiboon:
Each kidney has roughly one million filtering units (glomeruli). Creatinine is a muscle waste product that is almost entirely filtered, so blood creatinine can be used to calculate eGFR, but its level also depends on muscle mass, diet and body water. Cooked meat adds creatinine from outside the body, and dehydration reduces blood flow through the kidneys; both temporarily lower eGFR without damaging the filters.
Over the long term, excess salt causes fluid retention and high blood pressure. That pressure is transmitted into the filters, making the filter wall leak albumin into the urine. Leaked albumin triggers inflammation and scarring in kidney tissue, the main pathway of kidney decline. ACE inhibitor, ARB and SGLT2 inhibitor medicines directly reduce this pressure inside the filters.
Drinking more water than the body needs simply makes the kidneys excrete more water; it does not add filtering units or filtration pressure. Kidney protection therefore focuses on lowering pressure and albumin leak rather than increasing water volume.

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