Urine is a fluid precisely produced by the kidneys, carrying valuable intelligence about the body's internal operations. It may well be the "health barometer" most worthy of your attention.

The First Layer of Visible Codes: Color and Foam

Before urine is sent for laboratory testing, it has already sent initial signals through its color and foam. Before looking at a lab report, learning to observe your urine is the simplest first step, as your body has a built-in "urine color chart."

Ideal state: Clear and pale yellow. This indicates adequate hydration and good body water balance.

Gentle reminder: Dark yellow. The most common cause is insufficient water intake, requiring timely hydration.

Red to be vigilant about: Persistent red or meat-washing water color (medically termed "gross hematuria") suggests possible bleeding in the urinary system; please seek medical examination promptly. Additionally, certain foods like red dragon fruit and beets may alter urine color.

Dark tea color to take seriously: This may indicate liver problems (elevated bilirubin), hemolytic anemia (hemoglobinuria), or severe muscle damage (such as rhabdomyolysis).

Milky/cloudy urine to pay attention to: Cloudy urine may suggest infection (pyuria); while characteristic milky, chyle-like urine may indicate lymphatic issues (such as chyluria). Furthermore, in cold weather, the precipitation of salt crystals in urine can also cause transient cloudiness; this is a normal physical phenomenon and usually does not require excessive concern.

Secrets in the Foam

Foam during urination is normal in most cases. However, if a layer of fine, evenly sized foam appears and does not dissipate after resting for 15-30 minutes or more (medically termed "pathological foamy urine"), it may indicate elevated protein levels in the urine and damage to the kidney's filtration barrier (increased permeability of the glomerular filtration membrane), warranting further examination to determine the cause.

Core "Codes" on the Urinalysis Report

When you get your lab report, do not worry about the upward and downward arrows or plus/minus signs. Let's first decode a few key health indicators.

Code 1: Urine Protein (PRO) – Is the Kidney's "Filter" Intact?

Healthy kidneys firmly retain proteins in the blood. A "+" sign on the report means protein may be leaking into the urine. Occasional mild positivity (±) may be related to fever or intense exercise. However, persistent proteinuria requires vigilance for underlying kidney problems.

Code 2: Leukocytes (LEU) – The "Signal" for Inflammation and Infection

Significantly elevated leukocytes (especially when accompanied by symptoms like frequent and urgent urination) usually point to urinary tract infections, such as common cystitis or pyelonephritis. Additionally, accidental contamination during sample collection in women can also lead to false positives.

Code 3: Urine Glucose (GLU) – "Bypass Monitoring" of Blood Sugar Levels

Normally, glucose should not be detected in urine. A positive result for glucose suggests that blood sugar levels may have exceeded the kidney's reabsorption threshold (approximately 8.9~10 mmol/L, which varies from person to person), serving as an important clue for diabetes screening.

Other Key Indicators: A positive Nitrite (NIT) test often indicates the presence of reducing bacteria; Specific Gravity (SG) reflects the kidney's concentration and dilution functions; and pH is related to diet, stone types, or certain metabolic diseases.

What to Do When Abnormalities Are Found?

Step 1: Rule Out False Signals

A single, slight abnormality has limited clinical significance. First, consider whether there are interfering factors: Was a "clean-catch midstream urine" sample collected? Did women avoid menstruation? (If possible, it is recommended to retest about 3 days after the end of the menstrual period to prevent contamination from menstrual blood or secretions.) Have there been recent intense exercises, medication use, or special diets? These can all cause transient changes.

Step 2: Tools for In-depth Investigation

Doctors usually recommend retesting with morning urine. If abnormalities persist, more precise tests may be conducted, such as 24-hour urine protein quantification, Urine Albumin-to-Creatinine Ratio (UACR), or Urine Protein-to-Creatinine Ratio (UPCR).

Step 3: Pay Attention to "Combined Codes"

Single abnormal indicators and multiple combined abnormalities point in different directions:

"Proteinuria + Hematuria (dysmorphic red blood cells found in urine sediment microscopy)": Mostly suggests glomerular-origin damage, such as glomerulonephritis.

"Leukocytes + Positive Nitrite + Urinary Symptoms": Typically points to a urinary tract infection.

"Urine Glucose + Positive Ketones": Requires urgent evaluation for the risk of diabetic ketoacidosis.

Daily Care

Regularly monitoring urine, combined with a healthy lifestyle, is the best way to maintain kidney health.

Adequate Hydration: Adults should drink 1.5 to 2 liters of water daily, keeping urine pale yellow.

Prudent Medication Use: Avoid long-term or abusive use of medications that may harm the kidneys (such as non-steroidal anti-inflammatory drugs); always follow medical advice.

Healthy Diet: Maintain balanced nutrition, consume protein in moderation, and avoid high-salt diets to reduce the burden on the kidneys.

Do Not Hold Urine: Keeping urine in the bladder for too long will, on the one hand, cause over-distension of the bladder and affect detrusor muscle function, and on the other hand, provide more time for bacterial reproduction, increasing the risk of urinary tract infections. Chronic excessive urine retention may also elevate bladder pressure, increasing the risk of vesicoureteral reflux in susceptible individuals.

Regular Health Check-ups: Regular check-ups can detect diseases early, enabling early discovery, early treatment, and early recovery.

Warm Reminder: This article is for popular science purposes only and cannot replace professional medical diagnosis. If you feel unwell, please seek medical attention promptly.