Red blood cells in urine

1.Red blood cells in urine

Microscopic appearance:- in fresh urine, under high power objective, unstained erythrocytes (red blood cells) appear as pale bluish-green biconcave discs, about 7 um in size, with a smooth appearance, as opposed to the granular appearance of white cells. However, their appearance varies according to the constitution of urine.

 In a concentrated, hypertonic urine, the red cells appear crenated or shrunken due to loss of fluid. When urine is dilute or hypotonic, they appear swollen or rounded due to intake of more fluid. If the speci men is not fresh, the red cells appear as faint, colorless circles with a thin rim (shadow or ghost cells due to dissolution of haemoglobin from them

Dysmorphic red cells are distorted red cells which are fragmented or have cellular protrusions The presence of more than 20 % dysmorphic red cells indicates glomerular disease.

Note:- An inexperienced eye may confuse aibubbles, oil droplets or yeast cells with red cells. Introducing 2 % acetic acid under cover glass of the wet preparation will lyse the red cells, leaving the other structures intact. Alternatively, occult blood test may be performed on the urine specimen. The test will be positive in the presence of red cells.

Clinical significance--- In a normal urine sample occasional red cell (0-2/hpf or 3-12/ul) may be present in the sediment. When more red cells are detected in urine, the condition is known as haematuria (If there are no red cells in the sediment, but the occult blood test is positive, the condition is known as haemoglobinuria). The degree of haematuria may vary from a grossly bloody specimen to a normal appearing specimen showing a few red cells microscopically.

Increased number of red cells in urine may be seen in:

(i) Renal disease such as glomerulonephritis, calculus, acute infection, tuberculosis or tumour.

(ii) Lower urinary tract disease such as acute or chronic infection, calculus, tumour or cystitis.

(III) Extra-renal disease such as acute appendicitis, tumours of the colon, rectum or pelvis, malaria and subacute bacterial endocarditis.

(iv) Toxic reactions due to drugs such assulphonamides.

Note -Haematuria due to renal disease will also show the presence of casts in urine with the presence of urine protein.