What causes burning in the kidneys

Chronic kidney failure: first signs & symptoms

First signs

At the beginning, chronic kidney weakness often only manifests itself through minor signs of illness or even runs completely symptom-free. Often the kidney problems are overlaid by the symptoms of the underlying disease, e.g. B. by the symptoms of diabetes or vasculitis.

Early symptoms of kidney disease can include:

  • Increased excretion of slightly colored, pale urine
  • High blood pressure
  • Water retention (edema) in the legs, around the eyes or all over the body
  • Red urine

Symptoms

A gradual progression with little or no discomfort is characteristic of chronic kidney weakness. High blood pressure of over 140/90 mmHg occurring for the first time or an increasingly difficult to control high blood pressure can be an early sign of the disease.

Many patients often form pale, poorly concentrated urine and store water in the skin and subcutaneous tissue (edema). Foamy urine when urinating can be an indication of proteins in the urine. A healthy kidney excretes a maximum of 200 milligrams of protein per day, of which a maximum of 30 milligrams of the blood protein albumin. At higher values ​​one speaks of a microalbuminuria, from 300 milligrams of albumin per day of proteinuria. Some patients also excrete blood in their urine. If this happens in larger quantities, the urine is colored red (macrohematuria). Usually, however, there is only so little blood in the urine that it is invisible to the naked eye and can only be recognized by test strips (microhematuria).

As the loss of function progresses, the kidneys can no longer perform their tasks. This leads to disturbances of the water balance, the acid-base and electrolyte balance as well as other organ systems. The body is also more prone to infection. As the kidneys no longer produce sufficient amounts of the blood-forming hormone erythropoietin (EPO), the number of red blood cells decreases. Such anemia (anemia) leads to tiredness, weakness, difficulty concentrating and decreased exercise capacity.

A noticeable paleness of the skin is another possible clinical indication. In addition, patients often suffer from nausea, vomiting, or diarrhea shortly before starting dialysis. Other symptoms can include memory problems, itching and burning in the legs, and muscle and bone pain.

In the advanced stage of chronic kidney weakness, almost all organ systems are damaged by the kidneys' lack of detoxification function (uremic syndrome). Pathological changes can be found in the cardiovascular system, the blood-forming system, the gastrointestinal tract, the peripheral and central nervous system, the skin, the endocrine system and the bones.

Typical symptoms of end-stage kidney weakness (terminal kidney failure) are:

  • High blood pressure that can no longer be adjusted
  • Decrease in the amount of urine
  • Water retention (edema)
  • shortness of breath
  • Nausea, vomiting, loss of appetite
  • Irregular heartbeat
  • Drowsiness, drowsiness
  • Convulsions, coma

With the help of the so-called glomerular filtration rate (GFR), chronic kidney weakness is divided into five stages. The GFR is a laboratory value that is 90-130 milliliters per minute in normally functioning kidneys. This means that a healthy kidney cleans at least 90 milliliters of blood from freely filterable substances per minute and excretes them in the urine.

Stage I: GFR greater than 90 milliliters / minute

In this phase, patients often have no symptoms whatsoever. The blood values ​​for creatinine are still normal, only the protein excretion in the urine may be increased or there are other indications, e.g. B. ultrasound, for kidney disease. If possible causes are recognized now, a worsening of the disease can very often be prevented.

Stage II: GFR between 60-89 milliliters / minute

Even at this stage, kidney weakness can often not be detected by blood tests. The kidneys seem to be still functioning well, but closer examination shows kidney disease, e.g. B. with measurement of urine protein or with ultrasound. In addition, more precise measurements, e.g. the creatinine clearance, can demonstrate the onset of kidney weakness.

Stage III: GFR between 30-59 milliliters / minute

The kidney damage has now progressed so far that increased creatinine and urea levels are also measured in the blood. Those affected suffer from high blood pressure, decreased performance and fatigue more quickly. In stage III, the risk of cardiovascular diseases also increases significantly. The symptoms allow different interpretations and do not necessarily indicate kidney weakness. Drugs that are normally excreted via the kidneys now have to be reduced in their dose so that they do not cause any side effects.

Stage IV: GFR between 15-29 milliliters / minute

At this stage, so many kidney cells are already defective that the inadequate excretion of toxins affects the entire organism. The symptoms therefore increase: loss of appetite, tiredness, vomiting, nausea, nerve pain, itching and bone pain. Because the body excretes less salts and water, edema also occurs.

Stage V: GFR below 15 milliliters / minute

If the kidney function is severely restricted or if the kidneys fail completely, this is also referred to as terminal kidney failure. At this stage, the blood must be regularly cleaned of toxins by blood washing (dialysis), otherwise the body will be poisoned. Despite regular blood washing, terminal kidney failure can still lead to a yellow discoloration of the skin and itchy skin. Both are due to the storage of substances in the skin that should actually be excreted in the urine.