Diagnostic Procedures and Tests of Urine
Doing a thorough history and physical examination, physicians can diagnose diseases and ailments. Laboratory procedures and tests are available to confirm the diagnosis. In this issue, i will tackle common diagnostic procedures and tests involving the urine.
A. Routine urinalysis
– the urine is collected early in the morning and the specimen is examined immediately to avoid disintegration of the formed elements
– plastic bag devices and sterile bottles may be used to collect specimens after proper cleaning of the genitals and the diaper area.
B. Collection of 24 hour urine specimen
– the collection period begins just after the child has voided and this is discarded and after that all subsequent voidings are collected.
– Collected specimens are kept in the refrigerator until these can be delivered to the laboratory for examination
C. Catheterization
– this is an invasive procedure since a catheter is being inserted to the urinary tract in some indicated cases like in coma and states of shock where associated oliguria and anuria may be present
– strict sterility is adhered to in this procedure
D. Urine culture and sensitivity test
– this test is very important in the diagnosis of urinary tract infections
– the colony count of the bacteria can be determined and identified
– the sensitivity test is helpful to the physician in his choice of the right drug to use
E. Addis count
– this examination determines the physical status of the nephron
– the nephron is the structural and functional unit of the parenchyma
– Addis count may be done as a final test of recovery in children convalescing from acute glomerulonephritis or in cases of unexplained hematuria
F. Blood Parameters
– determinations of the following are useful guides in the evaluation of renal functions:
a. Blood urea nitrogen
b. Serum creatinine
c. Antistreptolysin O titer
d. Serum cholesterol
e. Total serum protein
f. Serum electrolytes
g. C2 level
G. Creatinine clearance
– this is the ratio of the amount of the substance excreted in the urine per minute to the concentration of the substance in the plasma
– this is a good measure of the glomerular filtration rate
H. Xray studies
– a plain KUB is requested to check for kidney stones but not useful if the stones are non-radioopaque
– also a good screening procedure in outlining the kidneys, ureters and bladder in the properly prepared patient
I. Intravenous pyelogram and voiding cystourethrogram
– these are contrast studies of the urinary tract
– the voiding cystourethrogram is more important in the evaluation of female patients with recurrent UTI
J. Sonograms and CT scan
– non invasive procedures but costly
– useful in detecting a number of renal disorders
– may detect a cystic or solid mass
K. Renal Biopsy
– indications:
a. Atypical cases of acute glomerulonephritis
b. Nephrotic syndromes resistant to steroids
c. Steroid-sensitive but frequently relapsing nephrotic syndrome
d. Bloody urine, unexplained
e. Unexplained hypertension
f. Persistent glomerulonephritis