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