Testing Information
pH: test to see whether a substance is acid (0-6.9) or base (7.1- 14).
Neutral is 7.
Sugar: to test for sugar Benedict's solution is used. Benedict's (a pale
blue solution) is added to the urine sample. The sample is then heated.
If the sample remains blue, no sugars are detected. A positive test,
indicating sugars in the sample, will range from a yellow to a red color.
Proteins: to test for proteins Biuret is used. A small amoun;c of the "
bluish Biuret is added to the sample. This wi!l, when combined with the
yellow urine, usually color the sample green. The mixture must then be
swirled or shaken. If the sample remains green, no proteins are
detected. A positive test, indicating proteins in the samplei will slq:6ÿ"
orange-red coloration.
RBCs, WBC:s, and crystals must be tested for by microscopic
examination. A sample of the urine will be placed on a slide and visual
observation under microscopic power will determine the presence of
t
any cells or crystals.
'"
Patient #1
Physical
I
Color
Clarity
Smell
pH
Yellow
Clear
Mild Odor
Acidic
Color Before
heating
Color After
Heating
Result
Blue
Red Precipitate
Biuret Test
Initial Color
Final Color
(proteins)
Green
Green
Microscopic
Red Blood
Cells
White Blood
Cells
Characteristics
of Urine
Benedict's Test
(sugar test)
Observations
+
Result
Crystals
+
Patient #2
Physical
Color
Clarity
Smell
pH
Yellow-Orange
Cloudy
Mild Odor
Acidic
Color Before
heating
Color After
Heating
Result
Blue
Blue
Biuret Test
InitialColor
Final Color
Result
(proteins)
Green
Reddish-Brown
4-
Microscopic
Red Blood
Cells
White Blood
Cells
Crystals
Characteristics
of Urine
Benedict's Test
(sugar test)
Observations
+
Patient #3
Physical
I
Color
Clarity
Smell
pH
Yellow
Cloudy
Mild Odor
Alkaline
Color Before
heating
Color After
Heating
Result
Blue
Blue
m
Biuret Test
Initial Color
Final Color
Result
(proteins)
Green
Green
Microscopic
Red Blood
Cells
White Blood
Cells
Characteristics
of Urine
Benedict's Test
(sugar test)
Observations
Crystals
+
Patient #4
Physical
Color
Clarity
Smell
pH
Yellow
Clear
Mild Odor
Normal
Color Before
heating
Color After
Heating
Result
Blue
Blue
m
Biuret Test
Initial Color
Final Color
Result
(proteins)
Green
Green
Microscopic
Red Blood
Cells
White Blood
Cells
Characteristics
of Urine
Benedict's Test
(sugar test)
Observations
J/
/
Crystals
Student
Ob
In this investigation, students will learn the basis of urinalysis and its application to tÿhe diagnosis of medical..
disorders. They will perform a simulated urinalysis on several urine samples, analyzing various factors. Lastly,
they will apply the basic principles of urinalysis in an attempt to diagnose three different medical disordersÿ
using three urine samples and one control.
B ckgj, und
o
Recognition of the presence of disease is based to some extent on the existence of objectivesigns o.r rec0g-
nizable abnormalities known as symptoms. Groups of signs and symptoms occurring in a characteristic pattern (referred to as sYndromes) are of value in diagnosis and in determining the distribution as well as the
cause, or etiology, of diseases.
The process of diagnosing a disease involves several steps. First, the patient will consult with the physician and
describe any particular Symptoms that he or she has previously noticed. The physician will then examine the
patient and note any signs that may be further indicative of the problem. Based On this initial assessment and
the patient's medical history, the physician may then make a diagnosis of the disorder. However, in some cases
it may be necessaryto go a step further and order various laboratory tests, ÿossibly including X-ray examinations. This Serves not only to arrive at a correct diagnosis, but also to rule out any other disorders which may
share the same signs and/or symptoms.
Tlÿere are many different types of specimens used in laboratory diagnosis, inciuding blood, feces, sputum,
stool, Uretllral and vaginal seci'etions, and cerebrospinal fluids. Urine testing is another very important diag-
nostic tool, invoMng the physical, chemical and visual examination of a urine sample. A thorough urinalysis
may provide more information about the general condition of the body than any other set of tests. Ud.nary
tract nfections, kidney matfunctio.n, diabetes and liver disease are just some of the medical problems that can
be diagnosed through urinalysis. In analyzing a urine sample, several factors are examined. These include the
appearance and color of the urine, the odorÿ the pH, and the sÿ=ific gravity.
Color and Apl:ÿarance
"l:he color of norma! udne can range from pale yellow to amber, depending on the concentration of th'e pigment urochrorne, which is the end product of hemoglobin breakdown. The appearance of the• Urine may
serve as an indication of a pathological condition. For instance, pale yellow urine may indicate diabetes
insipidus, granular Eidney, or may simply be very dilute due to ingestion of copious amounts of water. A milky
color might signify fat globulÿ or pus corpuscles, the latter possibly indicating a urogenital tract infection.
Reddish colors may be due to food pigmeO.ts (such as .bee. ts!, c.erta.i.ndrugs, or bloÿ in theLurint ,,Groÿnish,
coiors indicate either bile pigment (jaundice) or cerÿin 0ÿcÿenal InTecÿ0ns, sucn as moÿ.ÿ ÿu=ÿ.ÿ ÿ,ÿ
Pseudomonas species. Lastly, brÿtnoblack Urine can indicate Iÿhenol or metallic pOisonings or nemormages
due to conditions such asrenal injury or malaria.
The odor of urine can vary greatJy according to both diet and pathology. An ammonia smell may result from
certain foods, while a fishy smell may indicate cystiÿs:.A fec. al smell could.be due to an intestinal-urinary tract
fistula, Other distinctive smells could be indicative ot dlsoraers sucn as acetonuna, which has an Overripe apple
smell, or diabetes, the urine of which can also be noted to be sweet-tasting.
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pH
The pH of normal udne ranges from 4.5 to 8.0, the acidity or alkalinity of which can fluctuate depending on
the type of food ingested. Pathological conditions can also affect the pH of urine. Fevers and acidosis lower
the pH, whereas anemia, vomiting, and ischuda (udne retention) raiÿ the pH.
spÿific .grÿ
Yet another.¢ornponent of urinalysis is the determination of specific gravity, which is a measure of the densio
ty of a substance in gm/ml as compared to the density of water, which has a specific gravity of 1.00 gm/ml.
The specific gravity of udne usually ranges 'between t .015 and 1.025, although numbers slightly higher or
lower may be normal for people with diets either very high or low in fluid content. Specific gravity is generally inversely proportional to urinary volume. A pathological low specific gravity indicates nephdtis, whereas a
pathological high specific gravity indicates either nephritis or diabetes meUitus.
Drug scrÿning
One of the ways in which urinalysis is used is for the screening of drugs. A urine sample can be tested for drug
overdose and toxicity, or for the presence of abused drugs, commonly including amphetamines, barbiturates,
cannabinoids, cocaine, methadone, benzodiazepines, rnethaqualone, and opiates. This test is very useful as a
pre-employment drug screen. One limitation, however, is that this test provides only qualitative detection o(
drugs since quantitation of drug levels are not recommended. This is because urine levels are Ume and clear-
ance dependent and are not directly related to toxic symptoms seen clinically.
Pregnancy testing
Another important use for urinalysis is that of pregnancy testing. When a woman becomes pregnant, a
hormone known as human chorionic gonadotropin begins to be secreted by the embryonic tissues short-
ly after fertilization. HCG secretion then increases until it reaches a peak in about fifty to sixty days; thereafter, the HCG concentration drops to a much lower level and remains relatively stable throughout the
pregnancy. Because HCG is excreted in the urine, urinalysis is used to detect this hormone, thereby indi-
cating the presence of an embryo. Such a pregnancy test may give positive results as early as eight to ten
days after fertilization.
Microscopic observatians
The microscopic examination of urine is a vital aspect of routine urinalysis. Urine is made up pdrnadly of water,
with some salts and organic rnatedals dissolved in it. Inorganic substances nprmally found in the udne include
the sulfates, chlorides, phosphates, and ammÿ)nia. Crystals, casts, cells and microorganisms are among the significant elements found in the urine sediment.
Crystals
The variety of crystals and amorphous compounds found in the normal urinary sediment may represent both
the end product of tissue metabolism and the excessive consumption of certain foods or drugs. The type Of
crysta! or amorphous compound depends to some extent on the pH and osmolality of the urine. The presence of some crystals are qf little or no signÿcance while others constitute a positive diagnostic test. Common
crystals may be present normally in add, neutral or alkaline urine. However, abnormal tyÿ.s of crystals are
almost always associated only with acid or neutral udne.
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Urine Type
Crystal Type
Possible Indications
Alkaline
Calcium Phosphate
Calculi (stone) formation
Alkaline
Triphosphate
Calculi formation
Obstructive uropathy
Urinary tract infection
Proteus mirabilis infection
Alkaline
Calcium carbonate
Calculi formation
Acid
Calcium oxalate
Excessive intake of oxalate rich food
(ex: spinach, garlic, tomatoes, oranges)
Hyperoxaluria
Ethylene glycol poisoning
Diabetes mellitus
Acid
Uric acid
Gout
Leukemia
High purineÿmetabolism
Chronic nephritis
Acid
Hippuric acid
No clinical significance
Abnormal
Leucine
Severe liver disease ÿleucine &
Tyrosine
tyrosine may occur together)
Cystine
Calculi, congenital cystinosis, congenital
cystinurea (cystine present)
Sulfonamide
Casts
Casts in the urine are particularly significant because they represent cylindrical molds formed in the renal tubular lumina. They are formed by the precipitation of proteins and agglutination of ceils within the renal tubules.
Casts are classified into several major types: hyaline, epithelial, granular (coarse and fine), fatty, waxy, redblood cell, and white-blood cell. Because casts originate within the renal parenchyma, their presence in the
urinary sediment often provides important diagnostic clues as to the underlying renal pathology. For example, the presence of red-blood-cell casts is always indicative of renal parenchymal disease, especially glomeruIonephritis. The formation of casts is favored in a number of pathologic conditions in the nephron. These
include: (1) the presence of protein constituents in the tubular urine, (2) increased acidification, and (3)
increased osmolar concentration. A reasonable conclusion, then, is that casts will be formed principally with-
in the distal convoluted tubules and the collecting ducts because the urine becomes maximally acidified and
concentrated in this segment of the nephron.
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Ceils
iÿ has ÿ imÿrÿ to ÿ ÿ ÿus rÿuÿ in mÿbr'ÿ'ÿ dÿ ÿ ÿ ÿnd sÿ'ÿy. Thÿ
will ÿuÿ vÿ'dÿ ÿ ÿ ÿuÿr ÿ, cEmÿj,.ÿi mÿ ¢Iÿ of bÿ oÿ Sw'ÿmÿ,
shdrÿrÿ or iÿ sÿ'ÿ:ÿ ÿ rnay also rÿ dÿae to ÿ fi:ÿr ilÿ iÿ ÿto
vaÿtions in urirÿ ÿÿ ÿI pH, m toÿ ÿÿ mÿ cÿ ÿd ÿ and toÿl
ha! veÿl, decoy, multinudÿtÿd giant, sqÿ ÿ eÿ'ÿl, ÿ fat, ÿ oÿ and whÿ oÿ.
Albumin, gkÿ:o.ÿ and ÿtoÿs
The presence of various suÿes in the urine that are not normally there can, in some cases, be an indication of
a disorder. For example, the presence of albumiu (a pÿsma protein that helps regulate the osmotic concentration
of the blood) in a urine sample may indicate a kidney malfunction sÿnce one of the functions of the kidneys is to illter out albumin and glucose from the waste material and return them to the body. Therÿforÿ the ÿe of glucose in Udne can be a positive indication of another disorder, namely, diabÿ-.ÿ rnellitus. Diabetes mellitus is characterized bya defidency of insulin. The hallmark of diabetes is an increÿe in the concentration of blood sugar (hyperglycemia). When the blood sugar reaches a certain high concentration, it exceeds the renal thregÿ=ÿcl and the kidneys begin tq excrete ÿ excess. At this point, glucose a.pldears in the urine (glycosuda). Other symptoms of diabetes rnellitus include the dassic triad, that is, excessive unne output ÿria), dehydration accompanied by great
• thirst (polydipsia), and increased appetite (polyphagia). The person is aLso likely to lose weight and the ability to
grow or repair damaged tissues is do::reased. In the case of diabetes,, anothÿ., sub.sÿnce tÿ.t mÿght.be !ou. nd in the
urine is ketones. This may occur due to the utilization of fats at an abnormally nign ra[e, mus causing v,eÿone oocÿ
ies tO accumulate faster than they can be oxidized. Ketones may also appear in the urine when carbohydrateTnetalo=
olism is inadÿluate. A person may have ketonuda when he or she ÿly begins a very low carbohydratle diet.
, PhenylÿetonÿH.a
Urinalysis is also useful in assisting in the detection of a condition known as phenylketonuda, PKU is a failure of
the body to produce the enzyme necessary to oxidize phenylalanine to tyrosine, namely, phenylalanine--hydroxo
ytase. PKU is a recessive genetic trait whose inddence is somewhat over 1:11,000 in the United States. PKU causes nerve anÿl brain damage, accompanied by mental retardation if left untreated. However, by reducing or etirn-
inating phenylalÿnine from the diet,, retardation does not occur; Because the iÿenylketones appear in the urine,
infants with PKU often have diapers with distinctive odors; this observation by Swedish mothers ultimately led to
the condusion by sdentists that PKU may be detected by cheddng the urine. However, udnalysis.is not used as
an initial screening for PKU. Ideally, newborns should be screened via a blood test when they are betweeri 48 to
120 hours of age and have been on a milk (protein) feeding for at least 24 hours. After birth, 2=6 weeks may pass
before phenylpynÿc add is excreted in the urine. After the diagnosis of PKU has been established, urine screening type tests may be used to follow adequacy of diet control. (Look at the nutrition label of carbonated drinks.
Some state that they contain phÿytketonurics, namely phenytalanine). State laws require PKU testing of infants
within 28 days or less; in some states, testing is required prior to hospital discharge regardless of age.