Urine - Everything about the topic!


Everyone produces liters of urine every day and excretes it. But what exactly is the yellowish liquid? What is it made of and what is its use? What does it mean when the urine color changes? Is that dangerous?

Urine, also known as “urine”, is an excretion product made by the body by the two kidneys.
Urine consists mainly of excess water that our body no longer needs. There are also various salts, urea and other substances that the body also wants to get rid of.

How is urine made?

The kidneys have a complex system of filters and tubes to produce urine.
All of the body's blood flows past the kidney's filters. It is first of all roughly filtered there. This creates around 150 to 180 liters of primary urine.
In primary urine, however, are i.a. Contain substances that are common to the body. Of course, the body doesn't want to lose this, but rather to keep it.

Therefore, in the second pass, the important substances in the primary urine are reabsorbed, this is also called resorption. The absorbed substances get back into the bloodstream.
The secondary urine remains with substances that are not commonly used by the body, such as Urea, uric acid or phosphate. This only makes about 1-2 liters of the original 150 to 180 liters. The secondary urine now enters the urinary bladder via the ureters. From there on, the person can consciously excrete the urine when "urinating".

Would you like to find out more about how the kidneys work and how urine is produced? Then we recommend our site to: The function of the kidney

You might also be interested in: Why is urine yellow?

How much urine is produced?

About 1 liter of blood flows through the kidneys every minute. This means that all of a person's blood passes through the kidneys every 5 minutes.
In the course of a day, around 150 to 180 liters of primary urine collect through the kidney's filters. Since the body can recover up to 99% through the subsequent tube systems, people only excrete around 1.5 liters of secondary urine, i.e. urine, per day.

Is the kidney or urine excretion essential for survival?

The kidney is a vital organ, especially as it can regulate the body's fluid and electrolyte balance very finely and can rid the body of harmful substances through the urine.
Because many of the complex mechanisms from filtering the blood to excreting the final urine can malfunction, some possible clinical pictures can also arise.

If the decrease in renal function decreases, one speaks of renal insufficiency. Above a certain extent, this can be accompanied by a shortened life expectancy. Find out more at: Life expectancy with renal insufficiency

Color of urine

The color of the urine can vary widely. If possible, completely healthy urine should appear light and almost colorless to yellowish. This indicates that the proportion of pure water is high and indicates that the body is adequately supplied with water.

The usual yellow color is caused by the breakdown and excretion of parts of hemoglobin, our red blood pigment. The less the urine is diluted by water, the more intense the color of the urine appears. The urine can sometimes turn yellow-orange in color.

Read more on this topic at: Why is urine yellow?

Can one infer diseases based on the color of the urine?

Yes, the color of the urine can provide important clues.
Usually the urine should be clear and light. Depending on what you eat and how much you drink, the color of the urine can vary from clear-light to clear-brown.

However, if the urine color is “different” and does not return to normal after a few visits to the toilet, this provides important information on possible diseases.
A clear diagnosis cannot be made based on the color of the urine.
This requires testing using urine strips (U-Stix) and, if necessary, further diagnostics.

E.g. Cloudy or cloudy pink urine indicates a urinary tract infection and very dark urine indicates a possible liver disease or gallstones.

Find out more at: Urine color - what's behind it?

Urine is not yellow - what's behind it?

The following are causes that the change in urine color could indicate:

  • Red urine: A reddish color often indicates that there is blood in the urine. This can happen, for example, through injuries to the urinary tract. In some people, however, the consumption of carrots or beetroot can also make the urine reddish.

  • Brown urine: Brown urine is a symptom of some liver diseases. These include jaundice, "jaundice". In jaundice, the bile pigment "bilirubin" can no longer be adequately absorbed by the liver and increasingly reaches the blood. The kidney filters it out of the blood, giving the urine a brownish color.

  • Whitish urine: A whitish discoloration of the urine is possible. It is often accompanied by cloudiness. In many cases the cause is an infection of the urinary tract. Kidney inflammation can also cause this. When infected, inflammatory secretions, which also contain white blood cells, accumulate. They cloud the urine whitish.

  • Very light-colored urine: Very light-colored urine can indicate excessive fluid intake. In rare cases, however, diabetes insipidus can also be behind it. This is a hormone deficiency disease. Here, however, those affected also have a strong feeling of thirst. In diabetes insipidus, the kidneys excrete too much of the urine that was originally filtered, which leads to a lack of water in the body. This can also happen through dysregulation of hormones or through taking medication.

  • Other discolouration of urine: Many medicines can also discolour urine, but so can food. If you notice discoloration of the urine, this does not primarily mean that the cause is a disease. If the color does not go away by itself, a doctor should be consulted. This can determine the cause with other diagnostic methods.

Further information on this topic can be found at: Urine color - what's behind it?

Urine is dark - why?

There are several causes that can make the urine appear darker. The causes can be harmless and temporary, but they can also indicate serious illnesses. The following are possible causes of urine darkening:

  • Decreased fluid intake:
    The color of the urine depends, among other things, on the amount of fluid absorbed. The more you drink, the less focused and the lighter your urine will be. If, on the other hand, you drink little or your body loses a lot of water through diarrhea, heat or exercise, the concentration in the urine increases. This makes the urine appear dark.
    If this cause is correct for you, you can normalize the color of the urine by drinking enough water.
  • Medication:
    Brown to black urine is often a side effect of Parkinson's tablets such as L-dopa or alpha-methyldopa. The dark color itself therefore has no disease value of its own.
  • Liver and gallbladder disease:
    When the blood pigment is broken down, the bile pigment bilirubin is produced. This is usually excreted by the liver and bile in the stool. Are there liver diseases such as Hepatitis, cirrhosis of the liver or if the bile ducts are blocked by gallstones, the bilirubin is increasingly excreted in the urine. This stains the urine darkly.
  • Metabolic diseases:
    Here, too, the urine can appear dark, e.g. in the context of a porpyhry.
  • Black skin cancer (malignant melanoma):
    Malignant melanoma is a malignant skin cancer that affects the pigment cells (melanocytes) of the skin. In this cancer it can happen that the body pigment melanin passes into the urine and turns it dark.

For more information on this topic, we recommend our page on: Dark urine - you should know that!

Urine is cloudy - why?

Usually the fresh urine should be clear. However, if the urine is cloudy, this usually indicates harmless diseases.

  • Opaque lighter:
    If the urine is cloudy, there are probably white blood cells (leukocytes) or bacteria in the urine. This can indicate a urinary tract infection and in some cases requires antibiotics to be taken.
  • Cloudy red-brown:
    If you have cloudy red-brown urine, the urine probably contains small amounts of blood, i.e. red blood cells. This can also indicate a simple urinary tract infection. In very rare cases, bladder or kidney cancer can also be behind it.
  • Cloudy - milky:
    If the urine is cloudy, it could contain fats. That comes e.g. with kidney dysfunction, but can also have other rare causes. A medical clarification is recommended.

In most cases, cloudy urine is caused by a simple urinary tract infection. Read more about this at: Urinary tract infection - you should know that!

Changes in urine

Findings that result in changes in urine are described below.

Bacteria in the urine

Bacteria in the urine are not necessarily indicative of illness.
The urine that collects in the urinary bladder is not completely sterile. When urinating, the urine comes into contact with the mucous membrane of the urethra and thus also with bacteria. These bacteria belong to the normal flora of the genitourinary tract, so they usually have no disease value. They include: Staphylococcus epidermidis, enterococci and, in some cases, Escherichia Coli, proteins and non-pathological Neisseria.

These bacteria usually do not cause any symptoms unless they are found in too high a concentration. Up to 10,000 bacteria per mL of urine are normal, unless you can tell that a species is particularly pronounced or dominant. An increase in the amount of bacteria above 10,000 / mL indicates a bacterial infection or a urinary tract infection.Common pathogens of urinary tract infections are, for example, Escherichia coli, Klebsiella and Proteus mirabilis. Staphylococci (especially the Staphylococcus saprophyticus) can also lead to urinary tract infections.
Various types of urine diagnostics can be used to detect bacteria. However, it is important to avoid contamination from genital skin or from standing the specimen for a long time.

Read more on this topic at: Bacteria in the urine - how dangerous is it?

Blood in the urine

A basic distinction is made between microhematuria, when blood cells in the urine can only be seen with a microscope, and macrohematuria, when blood is visible with the naked eye.
However, blood in the urine can have various causes. It can end up in the urine in a number of ways.

  • If the ureters are injured, for example with a ureteral stone (but also with kidney stones, bladder stones, etc.) or with trauma, there may be blood in the urine.
  • Tumors of the bladder, ureter, or kidney are another cause.
  • Infections or inflammations of the urinary tract often lead to microhematuria and, in severe cases, to macrohematuria.
  • Some parasites such as the pair of leeches in the blood urine dysfunction can also lead to blood in the urine.
  • In women, blood in the urine can also occur as a result of menstrual bleeding. In the context of endometriosis, for example, uterine mucosa can appear in the urinary tract and thus lead to additional bleeding.
  • Furthermore, some medications such as cytostatics or anticoagulants can cause bleeding.

If blood is found in the urine (other than menstrual blood), a doctor should be seen to determine the exact cause of the bleeding and control it. If you experience additional pain when urinating, you should consult a doctor as soon as possible.

You might also be interested in this topic: Blood in the urine

Protein in the urine

Excretion of egg whites (or proteins) in the urine is normal in small amounts. In general, the daily protein excretion should be around 60 to 150 mg.
If the protein excretion is higher than 150 mg, one speaks of proteinuria. Proteinuria can be detected in various ways, for example by a screening test for protein excretion or with Urinstixs. If the amount of protein is increased, but the concentration in the morning urine is below 300 mg / l, then one speaks of benign proteinuria. This form of proteinuria occurs more often after exertion such as exercise or stress, or during pregnancy.

Pathological proteinurias arise in the context of several diseases. Infarcts, breakdown of muscle fibers or blood cells, infections and bleeding of the urinary tract, for example, can lead to an increase in the amount of protein in the urine. Kidney disease and insufficiency can also cause this. Proteinuria can also be a sign of a malignant disease such as plasmacytoma.

The mild form of proteinuria is microalbuminuria (albumin excretion). Microalbuminuria is an early sign of kidney disease in the context of diabetes mellitus.

Further information on this topic can be found at: Protein in the urine - you should know that!

Fluffy urine

White, cloud-like admixtures in the urine that sink to the bottom are colloquially referred to as “flakes in the urine”. In reality, these are proteins.

These structures can also occur in the urine of healthy people, e.g. in the context of food, stress, fever or exercise. Reduced fluid intake can also lead to "flakes" in the urine.
So there doesn't have to be a disease behind it. It is important, however, that the urine picture normalizes as soon as possible.
If you often have protein admixtures, i.e. flakes in your urine, this can indicate illnesses. The kidneys come first. This normally ensures through its filter function that proteins do not pass into the urine.

Listed below are conditions that affect the kidney and urination. Therefore, they can cause the urine to appear flaky.

  • Kidney disease, cystitis
  • Inflammation of the prostate
  • Diabetes mellitus
  • High blood pressure
  • Pregnancy with complications, e.g. pre-eclampsia

For more information, we recommend our website to: Fluffy urine

Urine foams

Very often foamy urine indicates that there is protein in it. This condition is known as “proteinuria”.
Especially in men, the urine can foam up because it comes up with a steady stream or comes up with residues from foaming cleaning agents. If this is not the case, the foaming urine should be examined by a doctor.
The kidneys usually do not filter the proteins, which is why they cannot get into the urine from the blood. If that happens anyway, various underlying diseases can be behind it.
A particularly protein-rich food, as found in athletes in muscle building, sometimes leads to proteins in the urine. Under certain circumstances, the diet should be adjusted as it overwhelms the metabolism and can lead to kidney weakness.
The kidney itself is often the cause of the protein in the urine. If its filtration function is restricted, it becomes permeable to the large proteins. This can be the case with cysts in the kidney, kidney stones, inflammation of the kidneys, but also with underactive kidney functions, up to and including renal insufficiency.
In most cases, the cause of kidney failure is severe diabetes, vascular diseases such as high blood pressure, cancer of the blood or the use of certain medications.

Read more on this topic at: Protein in the urine - you should know that!

Urine smells

Normal, healthy urine is largely odorless. Here, too, the more colorless and odorless it is, the healthier it is. However, some foods can cause the urine to smell strong when healthy. The most prominent examples of this are asparagus, coffee, onions or garlic.
If the smell is strong and lasts for several days, food is unlikely to be the cause. There can be various problems behind this. Unpleasant odors can be caused by bacteria. This can occur in the case of kidney infections or urinary tract infections.
Some diseases can be detected by abnormal or foul smelling urine. These include diabetes, "maple syrup disease" and acidification of the blood through so-called "ketone bodies", as can occur in diabetes mellitus or in severe hunger.
Drinking a sufficient amount of water and avoiding certain foods will in most cases save you from bad-smelling urine.

Odor of fish in urine

A fishy odor in the urine can have several causes.

  • In the context of bacterial infection, particularly due to chlamydia, the urine can take on a foul fishy odor.
  • In women this smell can also arise from infection or inflammation of the vagina, in men from infection or inflammation of the prostate.
  • Infected kidney stones and inflammation of the renal pelvis can cause similar symptoms.
  • A rare disease called trimethylaminuria (TMAU) can also explain the smell of fish. This metabolic disease is characterized by the lack of special liver enzymes. This leads to a reduced metabolism of the trimethylamine, which is contained in fish or eggs. Those affected also complain of foul-smelling sweat and other secretions (vaginal secretions, saliva).
  • Taking certain medicines, such as some antibiotics, and certain diets can also affect the odor of urine.

Honey-sweet urine

Honey-sweet urine can be related to food intake. In this case, however, the odor of the urine should neutralize itself after a few visits to the toilet. If this is not the case, it could be caused by sugar disorder, diabetes mellitus.

Diabetes mellitus is a disease in which the body can no longer manage to lower blood sugar sufficiently.
When the amount of sugar in the blood reaches a certain concentration, the function of the kidneys is overwhelmed. In this case, one speaks of a kidney threshold. This so-called kidney threshold is approximately 200 mg / dl glucose in the blood. If the concentration of blood sugar is higher than the kidney threshold, sugar is excreted with the urine.

This is often the case with diabetes mellitus. Therefore, the typical signs observed are increased urine excretion (polyuria) and sugar excretion with the urine (glucosuria). That is why the urine "tastes" sweet.
This is where the name of the disease comes from: Diabetes means “flowing through” in Greek and mellitus means “sweet as honey” in Latin. So together this means honey-sweet urine.

You could have diabetes mellitus. Read more about this at: Symptoms of Diabetes Mellitus

urine pH

The urine pH of a healthy adult is around 5-7.5. It indicates how acidic, neutral or basic the urine is. Between 0-7 you are in an acidic environment, with 7-14 marking the basic area. Normal urine is therefore approximately neutral to slightly acidic. Depending on the composition of the urine, the pH value can change, which can also indicate diseases.
A pH value below 5 that is too acidic often indicates a very meat-rich diet. A severe state of hunger also leads to acidification of the urine. More rarely, acidic urine can be a sign of metabolic diseases, such as gout.

Too high a pH value above 7.5 can also occur due to diet. A purely vegetarian diet can be the cause.
Certain medications that are excreted through the kidneys raise the pH level. If the pH value rises in the blood and consequently in the urine, one speaks of alkalosis.
Urinary tract infections in particular can cause urine to become alkaline.
Test strips can be used diagnostically to determine the pH value. This makes it possible to assess the function of the kidneys for excreting acids and bases.

Read more on the topic: urine pH