Under the Microscopic Examination of Urinalysis, laboratories focus on looking for the presence of tiny particles such as cells or infection-causing germs in Urine that are NOT VISIBLE to the naked eye but may change the Physico-chemical and Chemical properties stated above.
For this purpose, laboratories need to investigate several drops of your Urine Sample under a Microscope.
Results are usually expressed as “no. of particles per HPF” where HPF stands for “High Power Field” that refers to the magnified view under the microscope. Urinalysis reports normally provide an adjacent column for “reference range” for each of these parameters, against your own Urinalysis Outcome. If any of the components are present in above average values beyond the reference range, it calls for additional testing. In a routine Urinalysis, the following particles are looked for:
HUMAN CELLS
White blood cells (WBCs)
Also called Leukocytes, this type of blood cells constitutes our immune system.
Normally, Urine may have 0-5 WBCs/HPF.
A value greater than this range suggests the presence of an active infection in any of your organs in your Urinary System (Kidney, Ureter, Urinary Bladder or Urethra)
Red Blood Cells (RBCs)
Presence of RBCs, also called Erythrocytes in urine is technically termed Hematuria.
Normally, your urine report should report “Nil” or “Negative” in terms of RBCs in the urine.
Presence of even “trace” quantities of RBCs is abnormal. It may suggest Kidney Damage, Kidney Disease, Stones or a tumour in your urinary tract. Immediate medical attention is necessary in this case.
Epithelial Cells
These are special cell types that line the surfaces of different organs in your body.
In the urinary system, these form the lining of your kidney filters and urinary tract from within, such that these cells come in direct contact with urine when it flows from kidneys to your urinary bladder.
Normally, 1-5 epithelial cells/HPF may be found in Urine.
Any more than that raises the possibility of having a condition causing increased epithelial cell sloughing & removal with urine. This finding could appear with kidney stones, sustained raised high Blood Pressure, weak immune system as in Diabetes, enlarged prostate gland in males or even during Pregnancy.
CASTS
Casts refer to stacks of human cells such as blood cells or cellular products such as certain proteins that pile-up on each other to form tiny tube-like structures in the urine.
These can either form within the kidney or get erroneously filter-out from blood to our urine in kidney disease to show up in our urine sample.
Normal Urinalysis Reports are “Nil” or “Negative” for Casts.
CRYSTALS
Urine is made of a number of chemicals as discussed in a previous article. Under certain conditions, these may end-up solidifying and depositing within the urine tubes as crystals – a precursor to stone formation.
The medical term for the presence of crystals (glass-shard-like floating particles) in Urine is “Crystalluria”. This is abnormal.
Healthy urine samples usually come up “Negative” or “Nil” for crystals.
GERMS
In the microscopic examination of Urine, laboratories look for the general presence of the following infection-causing organisms/germs in your urine sample.
- Bacteria
- Yeast
- Non-bacterial organisms (Parasites)
Normal Urine is sterile. It must not be positive for ANY of the above germs in good health.
However, if these are found even in the absence of clinical symptoms, your doctor will recommend a Urine Culture and Antibiotic Sensitivity (Urine C/S) to pinpoint the infection-causing organism and treat you accordingly.
Click on the image links below to learn about the parameters routinely checked during the “Physico-chemical Examination” and “Chemical Examination” of your Urine Sample
Reference:
Mayo Clinic Staff. (2014, February 15). Urinalysis: Results mayoclinic.org/tests-procedures/urinalysis/basics/results/prc-20020390
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