Blood

All information on blood

At a glance

Hematuria, i.e. the excretion of red blood cells (erythrocytes) in the urine, can have many causes. During the period or during intense sports, it is quite normal that blood is in the urine. However, blood also occurs in the urine in many diseases.

Therefore, careful clarification of the cause is absolutely necessary. In particular, hematuria may indicate a urinary tract infection, kidney disease, kidney stones or tumors (e.g. bladder cancer). Injuries to the kidneys, bladder or urinary tract can also lead to hematuria.

For more information

Macrohematuria is visible to the naked eye. From about 0.5 – 1 ml of blood/litre of urine, a macroscopic red colour of the urine results. The urine takes on a reddish tone that can go from flesh-colored, pink or bright red to strong red.

Microhematuria (up to 0.5 – 1 ml of blood/l urine) can only be determined by examining the urine by means of test strips or under the microscope.

Since the hematurias occur in many diseases even before painful symptoms develop, they are a relatively good early indicator.

The test strip for blood in the urine may also indicate myoglobinuria. Myoglobin is responsible for the transport of oxygen within muscle cells. It occurs only in the skeletal and heart muscle cells of mammals. Myoglobinuria is caused by the increased breakdown of muscle cells in the context of various diseases or in rhabdomyolysis, a dissolution of cross-striped muscle cells. This can occur after intensive training such as CrossFit, EMS, Body Building, with beginners or after a long training break. The effect is usually caused by severe muscle soreness.

Hemoglobinuria, i.e. free hemoglobin (red blood dye) in the urine, can also be diagnosed by means of test strips. It occurs when more red blood cells disintegrate, causing the hemoglobin to leak out of the erythrocytes and finally excreted via the kidneys. This can be caused by various toxins or malaria.

A reddish discoloration of the urine is not always an indication of a disease. Also some strongly colouring foods, such as beetroot, can discolor the urine. This discoloration usually disappears after 2 to 3 times urination.

Sources

  • Roche Diagnostics Deutschland GmbH (2014): Compendium of Urinalysis. Urine Test Strips and Microscopy, 1-196
  • Schuetz, E. et al. (1985): Effect of diuresis on urinary erythrocyte morphology in glomerulonephritis. Klin Wochenschr, 63, 575
  • Lahnsteiner, E. et al. (2004): Harnanalyse – praktisch zusammengefasst, 2. Auflage
  • Fogazzi, G. B. et al. (1996): Microscopic hematuria diagnosis and management. Nephron, 72, 125
  • Fogazzi, G. B. (1996): The erythrocyte cast. Nephrol Dial Transplant, 11, 1649.
  • Hebert, L. A. et al. (1995): Relationship between appearance of urinary red blood cell/ white blood cell casts and the onset of renal relapse in systemic lupus erythematosus. At J Kidney Dis, 26, 432.
  • Rogers, P.W. et al. (1973): Familial benign essential hematuria. Arch Intern Med, 131, 257
  • Reid, R.I. et al. (1987): Haematuria following marathon run, source and significance. bBr J Urol, 133
  • Nunmacher, Dr. (2018): Blut im Urin, URL: https://medlexi.de/Blut_im_Urin, Retrieved 18.06.2019
Status of information: Autumn 2019