Three hundred times a day, the entire volume of blood flows through the kidneys: 1500 liters of fluid, of which just under one-tenth is initially filtered out. Of this, in turn, only a small fraction passes out through the urinary tract along with waste products as urine – most is reabsorbed back into the bloodstream. In addition to blood purification, the kidneys have other important functions in our organism.
Symptoms of kidney function disorders
Disorders of kidney function are often first detected during routine blood tests; in contrast, for diseases in the draining urinary system, complaints often lead the patient to the doctor. Typical symptoms indicative of diseases in the bladder and urethra include problems with urination such as increased urination, burning and pain during urination, delayed urination, bladder weakness, and changes in odor or discoloration of the urine. They can indicate, for example, an irritable bladder, inflammation of the bladder or urethra, tumors or changes in the prostate.
But other diseases can also manifest themselves through complaints in the urinary tract, for example, diabetes through increased urination (polyuria) or porphyria through discoloration of the urine. Renal pelvic inflammation may be manifested by a pulling pain in the flank and fever, and kidney or urinary stones cause massive colic if they get stuck.
Understanding lab values: A check of the most important abbreviations
The medical history
Usually, by asking the patient specifically about his medical history (anamnesis), the described complaints can already be assigned to probable diseases. The initial focus is on the current symptoms – where, when and how often they occur, whether they started suddenly or have been present for some time, and whether other complaints are present. Other illnesses experienced or chronic, previous operations or accidents, medications taken and illnesses in the family are also important.
Basic diagnostics
Physical examination is usually performed with the patient standing or lying down. Externally visible signs of disease (inspection) include water retention and pale or yellowish skin.
During palpation, the physician can examine the kidneys (at least in slim people) and check the filling status and sensitivity of the urinary bladder, especially if he uses his stethoscope for listening at the same time (auscultation); during examination of the rectum, the prostate can be palpated. Tapping (percussion) in the area of the flanks reveals painfulness of the kidney bearings – possible indication of inflammation or a stone.
Urinalysis is one of the most important tests for diseases of the urinary tract. Not only can the amount of urine be determined, but the urine sample can be examined under the microscope for admixtures (e.g. blood or inflammatory cells) and the presence and amount of certain substances can be tested. Substances such as uric acid, proteins and sugars are usually absent or present only in small amounts – and provide indications of metabolic diseases such as gout and diabetes.
If an infection of the kidney or bladder is suspected, a “urine culture” can be prepared to determine the presence of germs. Blood samples are usually examined at the same time, which can be used to make statements about kidney function in particular.
