LabDx

11/17/1999

handout from library—do not include table 1 (it is reference material)

urinalysis

Macroscopic urinalysis:

Paper or plastic dipstick—has chemicals to change colors depending upon the chemistry of the urine

Direct visual observation
N is pale to dark yellow or amber in color and clear
N urine volume is 750-2000 ml/24hr
Turbidity or cloudiness may be caused by excessive cellular material or protein in the urine or may develop from crystallization or precipitation of salts upon standing at room temperature or in the refrigerator
Clearing of the specimen after addition of a small amount of acid indicates that precipitation of salts is the probable cause of turbidity
PH goes up
A red or red-brown (abnormal) color could be from a food dye, eating fresh beets, a drug or the presence of either hemoglobin or myoglobin. If the sample contained many RBC, it would be cloudy as well as red
Frank hemoturia—visible on inspection (otherwise have to be seen on a microscopic)

PH—glomerular filtrate of blood plasma is usually acidified by renal tubules and collecting ducts from a pH of 7.4 to about 6 in the final urine. However depending on the acid-base status, urinary pH may range from as low as 4.5 to to as high as 8.0. The change to the acid side of 7.4 is accomplished in the distal convoluted tubule and the collecting duct
Specific gravity—directly proportional to urine osmolality which measures solute concentration—measures urine density, or the ability of the kidney to concentrate or dilute the urine over that of plasma. Dipsticks are available that also measure specific gravity in approximations. Most labs measure specific gravity w/a refractometer—b/w 1.002 (dilute) and 1.035 on a random sample should be considered normal kidney function is normal. Since the sp gr of the glomerular filtrate in Bowman's space ranges from 1.007 to 1.010, any measurement below this range indicates hydration and any measurement above it indicates relative dehydration—similar to hematocrit of the CBC

If sp gr is not >1.022 after a 12 hr period w/o food or water, renal concentrating ability is impaired and the pt either has generalized renal impairment or nephrogenic diabetes insipidus. In end-stage renal ds, sp gr tend to become 1.007 to 1.010—isouria
Any urine having a specific over 1.035 is either contaminated, contains very high levels of glucose, or the pt may have recently received high density radioopaque dyes (IVP—intravenous pyelogram) intravenously for radiographic studies or low molecular weight dextran solutions. Subtract 0.004 for every 1% glucose to determine non-glucose solute concentration

Done on whole urine
Semi-quantitative tests should be preformed on the supernatant of centrifuged urine since the cells suspended in N urine can produce a falsely high estimation of protein
Only small plasma proteins filtered at the Glomerulus are reabsorbed by the renal tubule
Tam-Horsfall protein—is found in N urine
Does not exceed 150mg/24hr or 10mg/100mL in any single specimen
150mg/day is defined as proteinuria

Bromphenol blue—albumin sensitive, along w/globulins and Bence-Jones protein poorly
Trace positive results 10mg/100mL or about 150mg/24hr (upper limit of N)

less than 0.1% of glucose is normally filtred by the Glomerulus in urine (<130mg/24hr)
glycosuria—excess sugar in urine—diabetes mellitus
glucose oxidase test—tests for glucose and can miss galactose and fructose