#urinetest #urineformation #urineanalysis
Urinalysis aka Poor man’s renal biopsy or liquid biopsy.
It comprises of physical,chemical and microscopic examination.
It involves Colour ,Odour , pH , Specific gravity, Glucose, Protein, Bilirubin, urobilinogen, Ketones , Haemoglobin and myoglobin, Leucocyte esterase and nitrites.
3 ways to obtain a urine specimen : spontaneous voiding, catheterisation , percutaneous bladder puncture.
For spontaneously voided urine, a midstream sample should be collected after cleaning of the external genitalia.
If a patient has an indwelling catheter, a fresh sample should be sent for analysis.Suprapubic needle aspiration of the bladder is used when urine cannot easily be obtained by other means, most commonly in infants.
The use of an early morning urine sample is suggested by KDIGO guideline especially for the measurement of albumin.Physical exercise should be avoided for at least 24 hours before the urine sample delivery to avoid exercise induced proteinuria and hematuria or urinary casts.
In women, urinalysis must be avoided during menstruation.For urine microscopy, a midstream sample of the first morning urine is recommended by some international guidelines.
However, the prolonged persistence in the bladder may favor the lysis of cells and casts, which may lead to false-negative urine sediment examination.
The container for urine should be clean, have a capacity of at least 50 ml, and have a diameter opening of at least 4 cm to allow easy collection.Wide based, capped, labelled with name, ID and time of collection.
Processing of sample: A sample should be analyzed within 2 to 4 hours of the time of collection to prevent cell lysis and precipitation of solutes.
If this is not possible, refrigeration of specimens at +4° to +8° Cassists preservation but may cause precipitation of phosphates or urates. Alternatively, chemical preservatives such as formaldehyde or glutaraldehyde can be used.