This can happen even when a person's food intake has not increased.
The weight change may be accompanied by swollen ankles, puffiness around the eyes, or abdominal swelling.
On the other hand, advanced kidney disease may contribute to weight loss.
Nausea, poor appetite, altered taste, and metabolic changes can make it difficult to maintain adequate nutrition.
People may gradually lose muscle mass and strength.
However, unexplained weight changes have many possible causes, including thyroid disorders, diabetes, digestive diseases, infections, and cancer.
Rapid weight gain accompanied by breathlessness or significant swelling should be assessed promptly.
Unintentional weight loss also deserves medical attention, particularly when it continues over several weeks.
Why Kidney Disease Can Develop Without Obvious Symptoms
One of the biggest challenges associated with kidney disease is that the body can compensate for declining kidney function for a surprisingly long time.
Each kidney contains approximately one million filtering units called nephrons.
These microscopic structures remove waste products and help regulate fluid and mineral balance.
When some nephrons become damaged, the remaining nephrons can initially increase their workload.
This compensation helps maintain many normal bodily functions.
As a result, someone can lose a substantial amount of kidney function without noticing obvious symptoms.
By the time symptoms become apparent, the disease may already be advanced.
This is particularly concerning because chronic kidney disease is frequently associated with diabetes and high blood pressure, both of which can develop without obvious warning signs.
Regular screening is therefore important for people at increased risk.
What Are the Main Causes of Kidney Disease?
Kidney disease can develop through several different mechanisms.
Understanding the underlying causes helps explain why prevention and early treatment matter.
1. Diabetes
Diabetes is one of the leading causes of chronic kidney disease.
Persistently elevated blood glucose can damage the small blood vessels inside the kidneys.
Over time, the filtering structures become less effective.
Early diabetic kidney disease may produce no symptoms.
One of the first detectable abnormalities is often albumin in the urine.
2. High blood pressure
Uncontrolled hypertension damages the delicate blood vessels that supply the kidneys.
This reduces their ability to filter blood effectively.
3. Kidney infections
Certain bacterial infections can travel from the bladder toward the kidneys.
A kidney infection, known as pyelonephritis, may cause fever, chills, back or flank pain, nausea, and urinary symptoms.
Repeated or severe infections can sometimes cause lasting kidney damage.
4. Kidney stones
Kidney stones form when certain substances in urine become concentrated and crystallize.
Small stones may pass without significant complications.
Larger stones can obstruct urine flow, produce severe pain, and sometimes contribute to infection or kidney damage.
5. Autoimmune diseases
Conditions such as lupus can cause the immune system to attack kidney tissue.
This can produce inflammation and interfere with filtration.
6. Inherited disorders
Some kidney diseases are genetic.
Polycystic kidney disease, for example, causes fluid-filled cysts to develop in the kidneys and may gradually impair their function.
7. Certain medications
Some medications can damage the kidneys, particularly when used inappropriately or in people with existing kidney disease.
Nonsteroidal anti-inflammatory drugs, including ibuprofen and naproxen, can reduce blood flow to the kidneys in susceptible individuals.
Certain antibiotics and other medications may also cause kidney injury.
This does not mean people should automatically stop prescribed medications.
Instead, medication choices and dosages should be reviewed with a healthcare professional when kidney problems are present.
How Can You Tell Whether Your Kidneys Are Working Properly?
The most reliable way to assess kidney function is through appropriate medical testing.
Symptoms alone cannot establish whether the kidneys are healthy.
Several tests are particularly important.
1. Blood creatinine test
Creatinine is a waste product produced by normal muscle metabolism.
Healthy kidneys remove creatinine from the bloodstream.
When filtration declines, blood creatinine levels may increase.
However, creatinine is influenced by muscle mass, age, diet, and other factors.
It should therefore be interpreted alongside other clinical information.
2. Estimated glomerular filtration rate
The estimated glomerular filtration rate, commonly called eGFR, is calculated using blood creatinine and other patient characteristics.
It provides an estimate of how effectively the kidneys filter blood.
An eGFR below 60 mL/min/1.73 m² for at least three months can indicate chronic kidney disease.
However, a single abnormal result does not automatically establish chronic kidney disease.
Doctors must consider whether the abnormality is persistent and whether other evidence of kidney damage is present.
3. Urine albumin-to-creatinine ratio
The urine albumin-to-creatinine ratio, or UACR, measures the amount of albumin leaking into the urine relative to creatinine.
Albuminuria can indicate damage to the kidney's filtering structures.
A UACR of 30 mg/g or higher may represent an abnormal finding that requires further assessment.
4. Urinalysis
A urinalysis can detect blood, protein, glucose, and other substances in urine.
It may also provide clues about urinary infections or inflammation.
5. Kidney ultrasound
An ultrasound allows doctors to examine the size, shape, and structure of the kidneys.
It can help identify cysts, certain structural abnormalities, and signs of urinary obstruction.
Not every patient needs all these tests.
A healthcare professional can determine which investigations are appropriate based on medical history and risk factors.
Seven Practical Ways to Protect Your Kidney Health
Although not every kidney disease can be prevented, several everyday habits can reduce the risk of kidney damage and help preserve kidney function.
1. Keep blood pressure under control
High blood pressure is a major risk factor for kidney disease.