Urine is the liquid excretory product that contains water and water-soluble waste compounds, generated in the metabolic processes taking place within the living cells. The water-soluble waste material found in urine are mainly nitrogenous products like urea, uric acid, and creatinine. Some hormones, enzymes, and mineral salts can also be found in the urine.
Urine is basically a transparent, colorless or pale yellow colored liquid, and is slightly acidic in nature. It's color may fluctuate a little from time to time, and mostly is not a cause for worry.
The characteristic straw or pale yellow color of urine is imparted by the pigment - urochrome. Any change in the color of the urine from pale yellow to dark yellow can be caused due to several factors. We will now have a look at the various causes and related symptoms for this condition.
Causes of Dark Yellow Urine
The color of urine can sometimes serve as an important health indicator. Changes in urine color can be caused by several conditions, ranging from inadequate fluid intake and consumption of some particular foods, to certain serious diseases.
Urine that is dark yellow in color is often a sign that one is dehydrated, or not drinking enough water. This can also happen when an individual sweats a lot, and does not replenish the lost water. Other important factors that can lead to dehydration are excessive vomiting and diarrhea. Due to dehydration, the urine becomes concentrated with nitrogenous waste material, and transforms from a colorless liquid to a dark yellow colored one. A high concentration of nitrogenous waste can give urine a peculiar odor, along with changing its color.
Medications and Supplements
Taking vitamin B-complex supplements can give the urine a dark or bright yellow color. B-complex vitamins are water-soluble vitamins, and hence, any excess amount that cannot be utilized by the body is excreted in the urine. Medications like quinine and quinine derivatives, rifampin, warfarin, nitrofurantoin, and sulfamethoxazole can impart a dark yellow or orange color to the urine too. One can also pass dark urine if he or she has recently used laxatives.
Consumption of Certain Foods
Another common reason behind temporary changes in urine color is the consumption of certain food items. For example, consumption of asparagus can make the urine dark yellow or greenish. Excessive consumption of foods rich in B vitamins, carotene and vitamin C, can also impart a bright to dark yellow color to the urine. On the other hand, consuming a large amount of beets can make the urine reddish-purple in color, while the consumption of blackberries and rhubarb can give it a red tinge.
Diseases and Disorders
Persistent yellow coloration of the urine can be caused by jaundice. Along with urine, jaundice can impart a yellow color to the skin and the sclera of the eyes as well. This change in color is brought about by the accumulation of bilirubin in the blood, which is a waste produced during the breakdown of old red blood cells. Under normal circumstances, the liver removes bilirubin from the blood, where it is combined with bile. This entire process can get disrupted when an infection accelerates the rate at which the red blood cells are broken down, or when the liver itself gets damaged due to an infection or exposure to certain substances.
An obstruction in the bile duct system can also cause jaundice by impairing the movement of bile in the digestive system. Infections of the liver such as hepatitis A, B and C, glandular fever, and leptospirosis, as well as an overdose of paracetamol, liver cirrhosis, autoimmune hepatitis, and liver cancer, can cause jaundice by damaging the liver. Diseases like malaria, sickle cell anemia, thalassaemia, Gilbert's syndrome, etc., can cause jaundice too. Conditions that can obstruct the movement of bile, and thereby cause jaundice include the formation of gallstones, pancreatitis, cholangitis, and cancer of the bile duct and pancreas.
Hemolytic anemia is another condition that can cause the urine to become dark brown or yellow in color. This condition is caused by the premature breakdown of the red blood cells, combined with the inability of the bone marrow cells to speed up their production to compensate this loss. This can result in a decrease of the number of red blood cells in the body. On the other hand, the increased breakdown of the red blood cells can raise the level of bilirubin in the blood, and cause jaundice.
Other Changes in Urine Coloration
Apart from a dark yellow color, the urine can turn orange, brown and greenish, due to several other underlying conditions.
- The urine may turn dark reddish-brown due to liver diseases like hepatitis and melanoma. It can be an indicator of copper poisoning as well.
- Smoky brown, and red or pink coloration of the urine can be caused by the consumption of foods like beet, fava beans, and blackberries.
- Blue or green urine can be associated with certain colors used in food and medicines such as methylene blue. Urinary tract infections and intake of medications like amitriptyline, indomethacin, and doxorubicin, can produce blue- or green-colored urine too.
- Blue urine can be a symptom of a bacterial infection and 'familial hypercalcemia', which is an inherited condition.
- Muddy/cloudy and murky urine, along with a bad smell, typically indicates a urinary tract infection.
- Red or pink urine may indicate the presence of blood in the urine, which commonly occurs due to an infection caused by kidney stones.
Dark yellow urine may not be accompanied by any other symptom, if it is not caused by an underlying disease or disorder.
- If it is caused by an infection of the urinary tract, one can smell a strong and offensive odor.
- One may experience the tendency to urinate frequently, and a burning sensation while urinating.
- An infection can also produce fever and abdominal pain in some individuals.
Before coming to any conclusion regarding the changes in urine color, it is very important to pay attention to the food that has been consumed recently, as well as the amount of fluid intake. This is because, temporary abnormal coloration of urine is commonly caused by the consumption of certain foods, and dehydration. Water plays a key role in draining the impurities out of the body through the urine. But if your urine is dark yellow for a considerable period of time, and there is also a bad odor, then be sure to seek medical attention.
A physician would carry out a proper study about the symptoms, and the medical history of the patient, to diagnose the condition. Several tests and examinations like a blood test, liver function test, examination of urine sample, urinalysis, as well as ultrasound of the kidneys and the urinary bladder, may be required to identify the specific dark yellow urine causes. The results of these diagnostic tests would, in turn, determine the course of treatment.
Disclaimer:This article is for informative purposes only, and should not be treated as a substitute for professional medical advice.