Urinalysis
Urinalysis
Urinalysis
BIOCHEMISTRY
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Urinalysis
*Michelle Dy Sim, Gellina Ann Ram Suderio, Jonnah Kristina Chua Teope
Department of Biology, 3Biology-6, Group # 7, College of Science
University of Santo Tomas, España Street, Manila 1008
March 2, 2009
Abstract:
Urine is a liquid waste product of the body secreted by the kidneys by a process of filtration from blood called urination and
excreted through the urethra. Urinalysis is an array of tests performed on urine and one of the most common methods of
medical diagnosis. The objectives of this experiment are to subject the urine sample acquired to several tests and to
qualitatively examine the presence of some normal organic constituents and pathologic organic constituents. Initial
examination includes the notation of the collection time, color, turbidity, acidity and pH of the urine sample. For the
qualitative exam of normal organic constituents, the test for urea, uric acid, indican and creatinine were conducted. In these
tests, the patient’s results were all normal. For the qualitative examination for pathologic organic constituents, Gunnings’s
test, Benedict’s test, Exton’s test, Smith’s test and Occult blood test were performed. The result obtained for the urine
sample was that the patient was healthy except for the fact that the patient might have diabetes.
Keywords:
• Urine
• Urinalysis
• Laboratory Tests
I. Introduction
Urine is a transparent solution that can range from colorless to amber but is usually pale yellow.
Urine is an aqueous solution of metabolic wastes such as urea, dissolved salts, and organic compounds
produced by the kidneys. It plays a vital role in maintaining homeostasis. The production of urine is
called diuresis.[1]
Urine ranges from pale yellow to amber because of the pigment urochrome. The color indicates
the concentration of the urine and varies with specific gravity. Dilute urine is straw colored, while
concentrated urine is deep amber.[2]
The aromatic odor of fresh, normal urine is caused by the presence of volatile acids. Analysis of
the pH of a freshly voided urine specimen indicates the acid – base balance. The urine reflects the work
of the kidneys to maintain normal pH homeostasis.[2] The kidneys maintain normal acid – base balance
primarily through reabsorption of sodium and tubular secretion of hydrogen and ammonium ions.[3]
Urinalysis is part of routine diagnostic and screening evaluations performed on urine that provide
a general overview of a person’s health.[4] Urinalysis is used as a diagnostic tool because it can help
detect substances or cellular material in the urine associated with different metabolic and kidney
disorders. It is routinely done in all patients admitted to the hospital, pregnant women and presurgical
patients. It is done diagnostically in patients with abdominal or back pain, dysuria, hematuria, or urinary
frequency. It is part of routine monitoring in patients with chronic renal disease and some metabolic
diseases.[2]
Most urine tests are performed for one of the following reasons: to diagnose renal or urinary tract
disease; to monitor renal or urinary tract disease; to detect metabolic or systematic diseases not directly
related to the kidneys.[2]
The process of urinalysis determines the following properties of urine: color, odor, turbidity,
specific gravity, pH, glucose, ketones, blood, protein, bilirubin, urobilinogen, nitrite, leukocyte
estaerase, and other abnormal constituents revealed by microscopic examination of the urine sediment.[3]
This experiment aims to subject the urine sample acquired to several tests and to qualitatively
examine the presence of some normal organic constituents and pathologic organic constituents.
II. Methodology
A. Initial Examination of Urine
The color, turbidity, acidity and the time when the urine was collected was noted.
B. Qualitative Examination for Normal Organic Constituents
1.) Test for Urea
A 0.5mL of 70% NaOH and 4 drops of bromine water was added to 1mL urine sample. After,
the evolution of N2 gas was observed.
Gunning’s test checks for ketone bodies in the blood or urine. Ketone bodies are three water –
soluble compounds that are produced as by – products when fatty acids are broken down for energy in
the body. The excess presence of ketones in urine is associated with diabetes or altered carbohydrate
metabolism.[3] Lugol’s solution consists of 5% iodine and 10% potassium iodide in 85% distilled water
with a total iodine content of 130mg/mL. A positive result shows a formation of iodoform crystals.
Glucose levels are measured to diagnose diabetes. The normal glucose level in the urine is
180mg/dL. Urine glucose levels of 300 – 500mg/dL are common with severe untreated diabetes.
Diabetes results from deficient insulin or decreased sensitivity to insulin. The results of a urine glucose
test are abnormal in cases of renal glycosuria and diabetes mellitus.[2]
+ 2Cu 2+
+ 4OH- Cu O 2 (solid) + 2H2O
Normally, protein is not found in urine. This is because the kidney is supposed to keep large
molecules in the blood and only filter out smaller impurities. If the kidney is diseased, protein will
appear in the urine. Exton’s reagent is 5% sulfosalicylic acid in a solution of sodium sulfate. A cloudy
solution shows the presence of albumin.
A normal urine specimen should be clear. Cloudy urine may be caused by the appearance of pus,
RBCs or bacterias; however, normal urine also may be cloudy because of ingestion of certain foods.
Abnormally colored urine may also result from a pathologic condition or the ingestion of certain
medicines. Dark yellow urine may indicate the presence of urobilinogen or bilirubin.[2]
The kidneys assist in acid – base balance by reabsorbing sodium and excreting hydrogen. An
alkaline pH is observed in a patient with alkalemia. Bacteria, urinary tract infection, or a diet in citrus
fruits or vegetables may cause increased urine pH. Alkaline urine is associated with calcium carbonate,
calcium phosphate and magnesium phosphate stones. Acidic urine is generally obtained from patients
with academia, which can result from metabolic or respiratory acidosis, starvation, dehydration, or a diet
high in meat products or cranberries. Acidic urine is associated with xanthine, cystine, uric acid and
calcium oxalate stones.[2]
Urine pH becomes alkaline on standing, because of the action of urea – splitting bacteria, which
produce ammonia. The urine pH of an uncovered specimen will become alkaline because carbon dioxide
vaporizes from the urine. Dietary factors affect urine pH. Ingestion of large quantities of citrus fruits,
dairy products, and vegetables produces alkaline urine, whereas a diet high in meat and certain foods
produces acidic urine.[2]
Protein is a sensitive indicator of kidney function. Normally, protein is not present in the urine
because the spaces in the normal glomerular filtrate membrane are too small to allow its passage. If
glomerular membrane is injured, the spaces in the filtrate become larger, and the protein seeps into the
filtrate, then into the urine. If this persists at a significant rate, hypoproteinemia can develop as a result
of severe protein loss through the kidneys. This decreases the normal capillary oncotic pressure that
holds fluid within the vasculature and causes severe interstitial edema.[2]
Specific gravity is a measurement of the kidney’s ability to concentrate urine.[3] Specific gravity
is used to evaluate the concentrating and excretory power of the kidneys. High specific gravity indicates
concentrated urine. Low specific gravity indicates dilute urine. Specific gravity refers to the weight of
the urine compared with that of distilled water. Particles in the urine give it weight or specific gravity.[4]
Leukocyte (WBC) esterase is a screening test used to detect leukocytes in the urine. Positive
results indicate urinary tract infection. Leukocyte esterase is nearly 90% accurate in detecting WBC in
urine.[2]
Like the leukocyte esterase screen, the nitrite test is a screening test for identification of urinary
tract infection. Nitrite screening enhances the sensitivity of the leukocyte esterase test to detect urinary
tract infection. Nitrite testing is only about 50% accurate in detecting WBCs in the urine.[2]
Normally, no ketones are present in the urine; however, a patient with poorly controlled diabetes
and hyperglycemia may have a massive fatty acid catabolism. The purpose of this catabolism is to
provide an energy source when glucose cannot be transferred into the cell because of insulin
insufficiency. Ketones are the end products of this fatty acid breakdown.[2]
IV. Conclusion
It comes to the conclusion that the patient is therefore free form any sickness aside from the fact
that the patient is already close to having diabetes, and should now be watchful of her sugar level intake.
V. References
[1] Urinalysis – Retrieved February 27, 2009
http://en.wikipedia.org/wiki/Urinalysis
[2] Pagana, K. D. and Pagana, T. J. Mosby’s Manual of Diagnostic and Laboratory Tests. St. Louis:
Mosby, 2002.
[3] Fischbach, F. and Dunning, M. B. III. A Manual of Laboratory and Diagnostic Tests. Philadelphia:
Williams & Wilkins, 2004.
[5] Harr, R. R. Clinical Laboratory Science Review. Philadelphia: F.A. Davis, 2007.
[8] Lehmann, C. A. Saunder’s Manual of Clinical Laboratory Science. Philadelphia: W.B. Saunders,
1998.
[9] Worthley, L. I. G. Handbook of Emergency Laboratory Tests. New York: Churchill Livingstone,
1996.