Why urine yellow color: from normal to abnormalities

Since ancient times, doctors have known that a healthy person should have straw-yellow urine, and its visual examination in a round glass vessel (uroscopy) was used to diagnose and predict the outcome of many diseases.

The Arabic treatise Liber Urinarium, which described the color of urine in various diseases, was translated into Latin in the 11th century, and from the 13th century – into many European languages.

Modern medicine relies more on the chemical composition of urine, which is determined during analysis, but its color is still taken into account and can provide important information about the health of patients.

Why is urine yellow?

Urine is the liquid "waste" of the body produced by the kidneys, consisting of water (at least 95%), salts (1.5%), urea and uric acid - products of protein metabolism and purine bases (normally up to 2.5%). In addition, toxins filtered by the kidneys and everything that should not be in the blood get into the urine. If everything is normal, the urine is light yellow.

What makes urine yellow? This is the result of the presence of the biopigment urobilin (urochrome), which is formed during hemolysis – the catabolism of heme (the non-protein part of hemoglobin in red blood cells). First, the hemes of erythrocytes, which have served their allotted 100-120 days, are broken down by macrophages in the spleen, liver, lymph nodes and bone marrow to biliverdin, after which the pigment bilirubin is formed from it. The kidneys are unable to filter bilirubin, so it enters the gallbladder and is excreted with bile. Under the influence of intestinal bacteria, bilirubin in bile is transformed into urobilinogen.

About half of the urobilinogen formed is reabsorbed through the portal vein into the liver (where it is oxidized to pyrroles); some remains in the colon and is converted into stercobilin, which gives feces their normal color. Some of the urobilinogen enters the venous bloodstream and ends up in the kidneys, where it is oxidized to the yellow pigment urobilin, which is excreted through the bladder and makes the urine yellow.

Risk factors

Risk factors associated with urine color primarily include age over 50, since hematuria-causing bladder and kidney tumors and prostatic hypertrophy are more common in older people.

As medical statistics show, more than half of all women have encountered a urinary tract infection, while men are more likely to have urolithiasis or nephrolithiasis.

Next come chronic kidney diseases, endocrine system dysfunctions and hereditary pathologies, in particular, hemolytic anemia with uremic syndrome, hemorrhagic vasculitis with glomerulonephritis, etc. Also, hematuria (with reddish urine) can be a consequence of systemic autoimmune diseases, such as lupus.

It should be borne in mind that with excessive physical exertion, less urine is excreted, and it has a more intense color and a characteristic ammonia smell.

Variations of Yellow Urine Color

The normal color of urine is from pale yellow to deep yellow. At the same time, weakly colored urine of light yellow color is observed when drinking large amounts of liquid or taking diuretics, and dark yellow - with insufficient hydration, which contributes to a higher concentration of urobilin.

It should be noted that doctors do not use such definitions as lemon-yellow urine, amber urine or saffron-yellow urine (i.e. reddish-yellow): there are standard terms for this in the descriptions and interpretation of laboratory urine tests. Although there are some "comparative" definitions: a reddish tint can be called the color of meat slops, and with dark urine - the color of beer.

Pigments and chemical compounds in the foods you eat can temporarily change the color of your urine. Everyone knows that when you eat beets or blackberries, your urine is yellow-pink, and after a good portion of raw carrots, your urine may turn a rich yellow. Tea and coffee lovers should remember that caffeine reduces the volume of urine excreted and makes it darker.

Yellow urine with a smell is considered a sign of consumption of foods rich in sulfur-containing compounds: meat, legumes, cereals, potatoes, onions, garlic and alcohol (including beer).

How does yellow urine change from medications?

Some medications taken orally also affect the normal straw-yellow color of urine. Urine acidifiers, such as vitamin C, aspirin (acetylsalicylic acid) or ammonia-anise cough drops, give urine a pinkish tint.

In addition, medications taken orally can change the level of urobilin and make the urine brighter. For example, bright yellow urine, as well as deep yellow urine, occurs in those who take a diuretic decoction of bearberry, Nitroxoline or Enteroseptol tablets (and other derivatives of 8-oxyquinoline) or riboflavin (vitamin B2). A strong smell of urine is noted by urologists when using dietary supplements with a high content of pyridoxine (vitamin B6).

Antibacterial drugs of the nitrofuran group prescribed for the treatment of bladder infections also significantly affect the color of urine. Fusazidin or Furagin colors urine dark yellow. Darker yellow urine in men can also be caused by taking Metronidazole (a derivative of 5-nitroimidazole), often used for trichomoniasis and trichomonas-induced urethritis and prostatitis.

Derivatives of 5-nitrofurfural Furamag color urine yellow of a darker shade, and Furazolidone also colors urine yellow-brown.

Many people experience bright yellow urine when taking Essliver Forte or Livolin-forte, hepatoprotective agents that contain a complex of vitamins and choline phosphoric acid ester, which promotes bile formation.

The drug Uropyrin (Phenazopyridine) for pain relief in cystitis can not only color the skin and whites of the eyes yellowish, but also give a rich yellow color to the urine.

Dark yellow urine is often observed in patients taking laxatives of plant origin (senna leaf or buckthorn bark), choleretic agents (Allochol, immortelle or corn silk decoctions), as well as antimalarial drugs based on quinine.

If you treat a child's cough with a mixture or syrup containing licorice root, the child's yellow urine may acquire a greenish tint for some time.

Pathological changes in the yellow color of urine

Quite often, the first symptoms of a particular disease manifest themselves in a change in the normal color of urine.

Moreover, its pathogenesis is associated either with processes in the urinary system, or with disturbances in the formation of urobilinogen, bilirubin and other chemical compounds eliminated with urine, which may be caused by disruptions in general metabolism, enzyme deficiency of various etiologies or diseases of the blood system with increased hemolysis.

Pale, light yellow urine combined with increased urine output (polyuria), frequent nighttime urination (nocturia) and a constant feeling of thirst indicate diabetes mellitus, the diagnosis of which is confirmed by the presence of sugar in the urine. Also read - Why is urine light and what does it mean?

If the urine is dark yellow, the reasons for the appearance of such a symptom may be functional renal failure or the development of obstructive jaundice. While yellow-brown urine may be caused by hepatitis and cirrhosis of the liver with hyperbilirubinemia, as well as various types of hemolytic anemia, including hereditary pathologies of the hemoglobin structure and enzyme-dependent pathologies of hemolysis of red blood cells. And if the urine darkens immediately after urination (under the influence of air), there should be a suspicion of the initial stage of skin cancer (melanoma).

Cloudy yellow or even yellow-green urine is often a symptom of bladder, urinary tract or kidney infections with the development of cystitis, urethritis, pyelitis or nephritis with the appearance of pus in the urine (pyuria). Urologists associate the pathogenesis of these inflammatory diseases with infection by the bacterium Pseudomonas aeruginosa.

Most often, yellow-red urine, as well as yellow-pink urine, is a manifestation of hematuria, that is, the presence of blood in the urine. And this is one of the symptoms of urolithiasis, the presence of renal calculi (damaging blood vessels) or glomerulonephritis (inflammation of the kidneys with damage to the epithelial and endothelial cells of the filtering glomeruli). In addition, a pinkish or reddish tint of urine may be associated with neoplasms localized in the urinary organs.

When the outflow of bile in the gallbladder is impaired, the urine is yellow-green. If the urine is yellow in women with a strong smell of ammonia, then the same infections should be suspected (cystitis, pyelonephritis, etc.). In men, yellow urine with a smell is noted with ureaplasmosis, liver cirrhosis, chronic pancreatitis, metabolic disorders, in particular, with ketonuria associated with diabetes.

Yellow urine and feces are possible with lamblia infection, gluten enteropathy (celiac disease), excess fat in the diet. Also, with malabsorption syndrome (lactase deficiency), both urine and feces are yellow, while the feces are distinguished by a greasy shine and foul odor. But with cholestasis and viral hepatitis, the urine is dark yellow, and the feces are light.

Change in urine color in a child

In infants of the first month of life, urine is colorless or pale yellow, and if the urine of a newborn is yellow (from deep yellow to dark yellow), it means that he lacks fluid. And the darker the color of the urine, the more obvious the lack of fluid in the child's body, and he needs to be fed more often.

Often, in the first two or three days after birth, a child's urine may be yellow-pink - due to the virtual absence of water in the colostrum, which is secreted from the mother's mammary glands at the beginning of breastfeeding and the associated increased concentration of urates (uric acid salts) in the newborn's urine. The urine color returns to normal very quickly, but if this does not happen, such a congenital anomaly in the newborn as renal hypoplasia is possible.

When urine is dark yellow, the cause may be either dehydration of the child's body (if the child is vomiting, has diarrhea, or has a fever), or a lack of breast milk.

In some cases, dark yellow urine indicates neonatal jaundice or hepatitis, cytomegalovirus hepatomegaly (enlarged liver), syphilitic hepatosplenomegaly (enlarged spleen and liver). In addition, yellow urine and feces can also indicate liver pathologies.

If a child of two or three years of age has yellow urine after urination that quickly darkens when exposed to air, then this is one of the first signs of alkaptonuria - a congenital disorder of the metabolism of the amino acid tyrosine, associated with the absence of a liver enzyme that oxidizes the intermediate product of tyrosine breakdown (2,5-dihydroxyphenylacetic or homogentisic acid).

Yellow-pink urine in children of primary and secondary school age - for example, after infectious tonsillitis - should cause serious concern for parents, as this may be a sign of acute post-streptococcal glomerulonephritis in children.

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Yellow urine in women

All the above-mentioned pathological changes in the yellow color of urine occur in both women and men. Except for one case: pregnancy.

So, yellow urine during pregnancy is considered normal. Moreover, pregnant women may have bright yellow urine - due to the kidneys working in an enhanced mode, as well as taking vitamin preparations.

However, in the first trimester, there may be dark yellow urine, which, first of all, may be associated with frequent vomiting during toxicosis. At later stages, this symptom appears due to fluid retention in tissues during edema, renal failure, anemia or cardiological problems. More information in the material - Dark urine during pregnancy

Darker urine can also be due to porphyrins in genetically determined porphyria. Its pathogenesis consists of the accumulation of metabolites of the synthesis of the non-protein component of hemoglobin - porphyrinogens, which are oxidized to porphyrin. In this disease, which can manifest itself in girls of puberty and worsen in women during severely calorie-restricted diets, during inflammation and during pregnancy, urine can be yellow-pink or yellow-red.

Diagnostics

If the urine color deviates from the normal, you should consult a doctor. In addition to a description of complaints and a complete anamnesis, urological diagnostics include a blood test and urine test (general, for red blood cells, enzymes, the presence of bacteria, for protein levels and sugar content, etc.). Laboratory test data allow an objective assessment of all biochemical parameters of urine and the identification of the causes of their changes compared to the norms.

Instrumental diagnostics are carried out: X-ray and ultrasound of the bladder, MRI of the kidneys, etc.

It is clear that with such a wide range of pathologies that can provoke this symptom, differential diagnosis is a key link in determining the etiology of existing deviations.

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Treatment and what to do if urine is yellow?

If cough, runny nose or pain can be treated with symptomatic means, then for all pathologies, when light yellow urine acquires other shades, etiological treatment is necessary. Moreover, the help of not only a urologist or nephrologist, but also specialists in the field of endocrinology and hematology may be required.

Treatment options depend entirely on the specifics of the disease, and only a doctor can determine the treatment method, for example, treatment of kidney inflammation, hemolytic anemia or diabetes. And the medications needed in each specific case will also be prescribed by the doctor. It may be necessary to prescribe antibiotics for cystitis, or take enzyme preparations and vitamins.

Prevention

According to experts, prevention is possible only in case of dehydration: if the urine has become darker and its smell is sharper, drink more water, and then the amount of urobilin in the urine will be physiologically normal.

Forecast

It is clear that genetic pathologies and autoimmune conditions have an unfavorable prognosis due to the impossibility of getting rid of them. But most bladder, urinary tract and kidney infections are curable - if you go to see a doctor in a timely manner.

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