Urinary time volume

The Urinary time volume (also Urinary time volume) comprises the amount of urine that is excreted in a specified period of time. As a rule, this period is 24 hours. The measured volume of urine is primarily used as a basis for assessing kidney diseases. Normally around 1.5 to two liters of urine are drained daily. The paired kidneys are responsible for the formation of urine and its elimination (diuresis). Diseases such as diabetes mellitus can cause the average urinary time volume to increase many times over.

What is the urine time volume?

With the urine excretion, the kidneys detoxify the body. At the same time, they help regulate the water and electrolyte balance. The formation of urine takes place in three steps. First, the so-called primary urine is filtered through the work of the kidney. The kidney corpuscles do that. Primary urine is an almost protein-free, unfocused ultrafiltrate that is produced when the kidneys are supplied with blood. The two kidneys produce a total of 180 to 200 liters of primary urine every day. This comes from the 1,500 to 1,800 liters of blood that flow through the kidneys every day. A person's entire blood flows through the kidneys around 300 times a day.

The composition of the primary urine is comparable to that of the blood plasma. The main difference is that larger blood components are captured by the vessels before they can be processed by the kidneys.

The primary urine then passes through the kidney tubules, where it is absorbed and secreted. Protein, electrolytes, glucose and water are absorbed, so that the secondary urine is created. About 19 liters are produced from it per day. These amounts of fluid are then further concentrated and finally reach the urinary bladder via the renal pelvis and ureters, from which they are excreted as urine. This is 1.5 to two liters per day. Thus the urine time volume is reached.

Function & task

The diuresis can fluctuate and in this context react to external influencing factors. The diuresis increases in intensity under exposure to the cold. Reduced air pressure from an altitude of 3000 meters has a similar effect. Numerous active substances in food also affect urine excretion. In this way, caffeine increases diuretic activity. The same goes for alcohol. Both substances suppress the production of the hormone ADH (antidiuretic hormone), which helps the kidneys to reflux water from the urine. When drinking a lot of coffee over a longer period of time, however, urine excretion stabilizes again at a lower level.

Medicine makes use of the principle of diuresis by stimulating increased urine excretion with special preparations in order to reduce the stress on the circulatory system.An increased urine volume indirectly reduces the amount of blood and thus the stress on the heart. This effect particularly helps patients with kidney and circulatory diseases.

Diuretic drugs are also used for poisoning. In this way, water-soluble toxins are washed out of the body. Controlling the urine volume is one of the preferred treatment methods, especially in intensive care medicine.

Diabetes patients, on the other hand, often have too much urination, which is why medication is usually used here as well. Increased urine production by the kidneys due to increased pressure in the urinary tract is called osmotic (water-drawing) diuresis. These processes are based on the retention of osmotically active substances in the tubules of the kidneys. They are not returned to the blood after filtration.

In order to keep the concentration of the relevant substances at the required level, more water flows passively into the urine to be excreted (polyuria). At the same time, it inspires drinking behavior. The osmotic diuresis can be brought about artificially by the administration of appropriate medicinal products to treat emergencies such as glaucoma, cerebral edema or acute kidney failure.

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Illnesses & ailments

Thanks to its pH value, the urine allows well-founded conclusions to be drawn about human nutrition. For this measurement, the urine time volume is used as a basis for reliable results. With a normal diet, the pH of the urine is between 4.6 and 7.5. It is therefore in the acidic range. A protein-based food intake shifts the pH value even more strongly into the acidic environment. A high consumption of vegetables, on the other hand, tends to lead to a shift towards the alkaline range.

The so-called urine status can indicate diseases of the kidneys (kidney stones, kidney tumor) and inflammation of the lower urinary tract in the early stages. Metabolic diseases such as diabetes mellitus and liver weakness are also displayed in this way. If proteins, nitrite, ketones and blood components can be found in the urine, this indicates various possible diseases.

Nephrology as a branch of internal medicine as well as urology, which is mainly responsible for operational matters, deal with kidney diseases in particular. The tasks involved are very diverse, because in addition to excreting the final products of metabolism, the kidneys also ensure the balance of the body's water balance, the long-term regulation of blood pressure and the control of the acid-base balance.

For example, the pH value of the blood, which has a decisive influence on kidney activity, may only fluctuate within a relatively narrow range, as otherwise life-threatening conditions can occur. Here, too, the measured and recorded urine time volume provides important information. It also provides information about the synthesis of glucose in the kidneys, their hormone production and the simultaneous breakdown of hormones such as peptides.