The kidney is an important metabolic and detoxification organ in the human body, silently performing the crucial tasks of filtering blood, producing urine, and excreting toxins. Urine serves as the most intuitive "barometer" reflecting kidney health. Most kidney diseases have no obvious pain in the early stages and are insidious in onset. By the time many people notice discomfort, kidney function damage has already become difficult to reverse.
Chen Wen, the director of the Nephrology Department at Hainan Chengmei Hospital, reminds us that subtle changes in daily urination are early warning signals from the kidneys. Especially, the following three abnormalities are not caused by common internal heat or insufficient water intake, and require timely vigilance and medical investigation.
1. Persistent foam in urine: be alert to proteinuria
Many people notice foam in their urine after urination, which is mostly attributed to drinking too little water and is considered harmless. Director Chen Wen explained that normal urine has few bubbles with large sizes, which quickly dissipate after being left still for a few seconds. However, if the urine exhibits fine, dense bubbles that persist even after being left still for 5-10 minutes, it is a typical sign of pathological foam urine, indicating core kidney damage.
The glomerulus of the kidney functions as a precise "strainer", retaining macromolecular nutrients such as proteins in the blood under healthy conditions, while only excreting water and metabolic waste. When the glomerular filtration membrane is damaged and its permeability increases, proteins can leak into the urine, resulting in proteinuria and subsequently producing persistent foam. Occasional transient foamy urine caused by strenuous exercise, high-protein diet, or staying up late is not a cause for concern. However, if it occurs repeatedly over a long period, it is likely an early manifestation of kidney diseases such as nephritis and nephrotic syndrome. Prolonged delay in treatment can lead to continuous damage to renal function.
2. Abnormal urine color: hematuria and dark tea-colored urine indicate potential risks of diseases
Normal and healthy urine is clear and light yellow, with its color only slightly changing depending on the amount of water intake. Director Chen Wen stated that, excluding external factors such as dragon fruit, beet, and medications, persistent abnormal urine color is an urgent distress signal from the kidneys, and two high-risk colors require special vigilance.
I. Meat washing water sample, pale red hematuria
It is divided into visible hematuria and microscopic hematuria found during physical examination. Painless visible hematuria is the most dangerous, as it presents with recurrent bloody urine without urinary frequency, urgency, or dysuria, and may indicate glomerular inflammation, kidney stones, urinary tract injury, or even occult lesions in the urinary system.
II. Dark tea-colored or soy sauce-colored urine
After excluding the factor of water deficiency, persistent dark urine indicates a decline in kidney metabolism and filtration functions, preventing toxins from being excreted normally. This is often seen in issues such as renal tubular injury and acute kidney injury, and should not be simply attributed to "excessive internal heat".
3. Abnormal urine output and nocturia: signals of kidney concentration function decline
Changes in urinary frequency and volume are often the most easily overlooked early signs of kidney disease. Director Chen Wen explained that healthy adults typically have a daily urine output of about 1500 milliliters, urinate 4 to 6 times during the day, and wake up to urinate 0 to 1 time at night. If urinary habits deviate from these normal ranges, it is important to be vigilant.
On the one hand, increased nocturia, with up to 3 or more trips to the toilet per night and a higher urine output during the night compared to the day, is a typical manifestation of decreased renal concentrating function. The kidneys are unable to fully concentrate urine and retain water during the day, leading to concentrated excretion of water at night, which is commonly seen in the early stages of chronic kidney disease.
On the other hand, a sudden change in urine output is observed. Urine output less than 400 milliliters in 24 hours is considered oliguria, while less than 100 milliliters is considered anuria, often indicating acute kidney injury or renal failure. Prolonged excessive urine output may also be caused by impaired renal tubular reabsorption function.
Director Chen Wen finally reminded that kidney disease can be prevented and controlled in its early stages. It is important to develop the habit of observing urine daily. If any of the above three abnormalities occur, it is necessary to go to the hospital for urine routine and renal function tests in a timely manner. Early screening and intervention are crucial to effectively protect kidney health and prevent minor issues from developing into irreversible kidney diseases.
Expert Introduction
Chen Wen, Director of Nephrology Department
Chief Physician, Professor, Master's Supervisor
Outstanding experts with outstanding contributions in Hainan Province
Leading talents in Hainan Province
Key experts directly connected with the Provincial Party Committee and Provincial Government of Hainan Province
Medical expertise
Skilled in treating primary glomerular disease, IGA nephropathy, lupus nephritis, hypertensive nephropathy, uric acid nephropathy, and diabetic nephropathy; especially proficient in the diagnosis and treatment of critical and complex diseases in nephrology, as well as clinical pathological diagnosis and treatment; proficient in the diagnosis and treatment of indications and complications of hemodialysis and peritoneal dialysis; proficient in the establishment of temporary and long-term vascular dialysis access and peritoneal dialysis access, as well as the management of complications.