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Why the urine is yellow: from the norm to the deviations
Last reviewed: 18.10.2021
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Since ancient times, the healers knew that a healthy person should have straw-yellow urine, and her visual inspection in a round glass vessel (uroscopy) was used to diagnose and predict the outcome of many diseases.
The Arabic tract Liber Urinarium, which described the color of urine for various diseases, was translated into Latin in the 11th century, and to many European languages in the 13th century.
Modern medicine relies more on the chemical composition of urine, which is revealed by the analysis, but its color is still taken into account and can give 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 - protein exchange products and purine bases (normally up to 2.5%). In addition, the urine is filtered by the kidney toxins and everything that should not be in the blood. If everything is normal, then urine is light yellow in color.
What gives the urine a yellow color? This is the result of the presence in it of the biopigment urobilin (urochrome), formed in the process of hemolysis - catabolism of heme (a protein-free part of the hemoglobin of red blood cells). At first the gemma of erythrocytes laid down for 100-120 days undergoes cleavage by macrophages of the spleen, liver, lymph nodes and bone marrow to biliverdin, after which the pigment bilirubin is formed from it. The buds can not filter bilirubin, so it enters the gallbladder and is removed along with the bile. Under the influence of intestinal bacteria bilirubin bile is transformed into urobilinogen.
About half of the urobilinogen formed by reverse absorption is passed through the portal vein to the liver (where it oxidizes to pyrroles); part remains in the large intestine and turns into giving the usual color of feces of stercobilin. And part of the urobilinogen enters the venous bloodstream and is found in the kidneys, where it oxidizes to the yellow pigment of urobilin, which is excreted through the bladder and makes the urine yellow.
Risk factors
Color-related urine risk factors, primarily include age after 50, because hematuria-causing tumors of the bladder and kidneys, as well as prostatic hypertrophy, are more common in the elderly.
As medical statistics show, more than half of all women have had a urinary tract infection, while men often have urinary or nephrolithiasis.
Then there are chronic kidney diseases, endocrine system disorders 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, for example, lupus.
It should be borne in mind that with excessive physical exertion, urine is released less, and it has a more intense color and a characteristic ammonia odor.
Variations of yellow color of urine
The corresponding color of urine is from pale yellow to rich yellow. At the same time, slightly colored urine of light yellow color is noted when using a lot of liquid or taking diuretics, and dark yellow - with insufficient hydration, which contributes to a higher concentration of urobilin.
It should be noted that physicians do not use such definitions as lemon-yellow urine, amber color or saffron-yellow urine (i.e., reddish-yellow): for this, there are standard terms in descriptions and deciphering of urine laboratory tests. Although there are some "comparative" definitions: a reddish hue can be called - the color of meat slops, and with dark urine - the color of the beer.
Temporarily change the color of urine can pigments and chemical compounds in the consumed foods. Everyone knows that when using beets or blackberries, urine is yellow-pink, and after a good portion of raw carrots can be saturated yellow color of urine. Lovers of tea and coffee should remember that caffeine reduces the volume of excreted urine and makes it darker.
Urine yellow with odor is considered a sign of eating foods rich in sulfur-containing compounds: meat, legumes, cereals, potatoes, onions, garlic and alcohol (including beer).
How does yellow urine change from drugs?
Some drugs taken internally also affect the normal straw-yellow color of the urine. Acidified urine preparations, for example, vitamin C, aspirin (acetylsalicylic acid) or ammonium anise drops from coughing, give the urine a pink tinge.
In addition, oral medications can alter the level of urobilin and make urine brighter. For example, urine of bright yellow color, as well as a rich yellow color of urine, occurs in those who take a diarrhea broth of bearberry, tablets Nitroxoline or Enteroseptol (and other derivatives of 8-hydroxyquinoline) or riboflavin (vitamin B2). A strong smell of urine is noted by urologists when using supplements with a high content of pyridoxine (vitamin B6).
Antibacterial drugs prescribed for the treatment of bladder infections also significantly affect the color of urine. Fusazidine or Furagin stains urine in a dark yellow color. Darker urine of yellow color in men can also be caused by taking Metronidazole (a 5-nitroimidazole derivative), often used for trichomoniasis and trichomonas caused by urethritis and prostatitis.
Derivatives of 5-nitrofurfurol Furamag stains urine in yellow of a darker shade, and furazolidone also stains urine in a yellow-brown color.
Many people have the color of urine bright yellow with the reception of Essley Forte or Livolin-Fort - hepatoprotective agents, which contain a complex of vitamins and a cholinophosphoric acid ester, which promotes bile formation.
The drug Uropyrin (Fenazopyridine) for the removal of pain in cystitis can not only color the skin and eye proteins in a yellowish color, but also gives a rich yellow color of urine.
Often observed urine is dark yellow in patients taking laxatives of plant origin (a sheet of hay or bark of buckthorn), cholagogue (Allohol, broths of immortelle or corn stigmas), and antimalarials based on quinine.
If you cough a child's medicine or syrup with a licorice root, then the child's urine yellow for a while can get a greenish tint.
Pathological changes in yellow urine
Quite often the first symptoms of a disease appear in the change in the usual color of urine.
In this case, its pathogenesis is associated either with processes in the urinary system, or with disturbances in the formation of urobilinogen, bilirubin, and other chemical compounds that are eliminated in the urine, which may be due to failures in general metabolism, enzyme deficiency of various etiologies, or diseases of the blood system with elevated hemolysis.
Pale urine of light yellow color in combination with an increased amount of excreted urine (polyuria), frequent night urination (nicture) and a constant thirst indicates diabetes mellitus, the diagnosis of which confirms 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 cause of the appearance of such a symptom may lie in the functional deficiency of the kidneys or the development of obstructive jaundice. While urine of yellow-brown color can be caused by hepatitis and cirrhosis of the liver with hyperbilirubinemia, as well as by various types of hemolytic anemia, including hereditary pathologies of the hemoglobin structure and enzyme-dependent pathologies of hemolysis of red blood cells. And when darkening urine immediately after urination (under the influence of air), there should be a suspicion of the initial stage of skin cancer (melanoma).
Urine of a dull yellow color and even yellow-green color is often a symptom of infections of the bladder, urinary tract or kidneys 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 with the bacterium Pseudomonas aeruginosa.
Most often, urine is yellow-red, as well as urine of yellow-pink color - the manifestation of hematuria, that is, the presence of urine in the admixture of blood. And this is one of the symptoms of urolithiasis, the presence of renal calculi (damaging blood vessels) or glomerulonephritis (inflammation of the kidneys with epithelial and endothelial cell damage of filter glomeruli). In addition, a pinkish or reddish shade of urine may be associated with tumors localized in the urinary organs.
When the outflow of bile is broken in the gallbladder, urine is yellow-green in color. If the urine is yellow in women with a strong smell of ammonia, you should suspect all the same infections (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 mellitus.
Urine and feces of yellow color are possible in case of infection with lamblia, gluten enteropathy (celiac disease), excess of fats in the diet. Also, in the syndrome of malabsorption (lactase deficiency) and urine and feces have a yellow color, while the feces differ in greasy gloss and off-smell. But with cholestasis and viral hepatitis - urine is dark yellow, and the feces are light.
Changing the color of urine in a child
In infants of the first month of life, urine is colorless or pale yellow, and if the urine of the newborn is yellow (from rich yellow to dark yellow), then it lacks liquid. And the darker the color of urine, the more obvious the lack of fluid in the body of the child, and it needs to be fed more often.
Often in the first two to three days after birth, the child may have urine yellow-pink - due to the lack of water in the colostrum, which is released from the mammary glands of the mother at the beginning of breastfeeding and associated with this increased concentration of urate (uric acid salts) in the urine of the newborn. Very quickly, the color of urine is normalized, but if this does not happen, such a congenital anomaly in a newborn is possible, like kidney hypoplasia.
When the urine is dark yellow, the cause can be either in the dehydration of the child's body (if the child has vomiting, diarrhea or fever has risen), or in a lack of breast milk.
In some cases, dark yellow urine indicates neonatal jaundice or hepatitis, cytomegalovirus hepatomegaly (enlargement of liver size), syphilitic hepatosplenomegaly (enlargement of the spleen and liver). In addition, urine and feces of yellow color may also indicate hepatic pathology.
If at the age of two or three years the child's urine yellow after urination quickly darkens when exposed to air, this is one of the first signs of alkaponuria, a congenital disorder of the amino acid tyrosine metabolism associated with the absence of a hepatic enzyme that oxidizes the intermediate cleavage product of tyrosine (2,5- dihydroxyphenylacetic acid or homogentisic acid).
Urine yellow-pink in children of junior and secondary school age - for example, after suffering an infectious tonsillitis - should cause serious concern to parents, as this may be a sign of acute poststreptococcal glomerulonephritis in children.
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Urine yellow in women
All the above pathological changes in the yellow color of urine take place both in women and in men. Except for one case: pregnancy.
So, the urine of yellow color during pregnancy is considered the norm. Moreover, pregnant women can have bright yellow urine - due to the work of the kidney in a strengthened mode, as well as the intake of vitamin preparations.
However, in the first trimester, urine can be a dark yellow color, which, in the first place, can be associated with frequent vomiting in toxicosis. In later terms, this symptom appears due to fluid retention in the tissues with swelling, kidney failure, anemia, or cardiac problems. More information in the material - Dark color of urine during pregnancy
Darker urine is also due to porphyrins in genetically determined porphyria. Its pathogenesis consists in the accumulation of metabolites in the synthesis of the non-protein component of hemoglobin-porphyrinogens, which are oxidized to porphyrin. In this disease, which can occur in girls of pubertal age and worsen in women during severely calorie restricted diets, with inflammation and during pregnancy, urine may be yellow-pink or yellow-red in color.
Diagnostics
If there is any deviation from the normal color of the urine, consult a doctor. In addition to the description of complaints and a complete history, urological diagnosis includes a blood test and urinalysis (total, for erythrocytes, enzymes, the presence of bacteria, protein level and sugar content, etc.). The data of laboratory tests allow objectively to evaluate all biochemical parameters of urine and to reveal the reasons for their changes in comparison with the norms.
There is an instrumental diagnosis: fluoroscopy 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 the key link in finding out the etiology of the existing deviations.
Who to contact?
Treatment and what to do if urine is yellow?
If a cough, runny nose or pain can be affected by symptomatic means, then in all pathologies, when the pale yellow color gets other shades, an etiological treatment is necessary. Moreover, it may be necessary to help not only the urologist or nephrologist, but also specialists in the field of endocrinology and hematology.
The treatment options completely depend on the specificity of the diseases, and only the doctor determines the method of treatment, for example, treatment of kidney inflammation, hemolytic anemia or diabetes mellitus. And the medicines needed in each specific case will also be prescribed by the doctor. You may need to prescribe antibiotics for cystitis, or take enzyme preparations and vitamins.
Prevention
According to experts, prevention is possible only in the case of dehydration: if the urine is darker, and its odor is sharper, drink more water, and then the amount of urobilin in the urine will be physiologically normal.