By the end of this session the reader should be able to:

  • Perform a urinalysis, including macroscopic examination, chemical examination, and microscopic examination
  • Discuss the causes of abnormally colored urine (brown-black, red, green to yellow-brown)
  • Discuss the causes of turbidity of urine
  • Discuss causes for ammoniacal, fruity, and acetone odors in urine
  • Discuss the reference ranges for urinary pH and specific gravity
  • Identify non-glucose reducing substances that may appear in urine
  • Know what substances will give a positive sulfosalicylic acid test
  • Identify causes of false negative glucose dipstick tests in urine
  • Identify causes of false negative heme dipstick tests in urine
  • Identify hyaline, leukocyte, erythrocyte, renal epithelial, granular, waxy, and fatty casts
  • Identify calcium oxalate, sodium urate, triple phosphates, ammonium biurates, amorphous phosphates, tyrosine, leucine, sulfonamides, and cystine crystals in urine and know at what urine pH (alkaline or acid) they occur


Students desiring to perform urinalysis on their own urines should collect their specimens into collection cups at the start of the laboratory session.

Students should get out their microscopes.

Instructors will then demonstrate urinalysis.

Students will then perform urinalysis on their own urine samples (optional) and on the urine samples provided in the laboratory.

Useful reference: Jennifer Benedict, M.D., School of Medicine Class of 2004. Independent Study Project. * http://meded-portal.ucsd.edu/isp/2004/urinalysis .


Amorphous crystals - The granular, noncrystalline precipitate of salts with no pathological importance.

Bacteriuria - The presence of bacteria in urine.

Bilirubinuria - The presence of bilirubin in urine.

Crystalluria - The presence of crystals in urine.

Cylindruria - The presence of casts in urine.

Dipstick urinalysis - A chemical urine test using test strips for the detection of albumin, glucose, ketone bodies, bilirubin, hemoglobin, bacteria, leukocytes, and other chemical constituents.

Glitter cells - Pale-staining, swollen, and degenerated neutrophils found in dilute urine, with cytoplasmic granules that exhibit a characteristic Brownian movement.

Glycosuria - The presence of glucose in urine.

Hyaline cast - A transparent cast composed of mucoprotein (Tamm-Horsfall protein).

Hydrometer - An instrument used for determining the specific gravity of a fluid.

Ketone body - Any compound containing the carbonyl group and having hydrocarbon groups attached to the carbonyl carbon.

Microscopic urinalysis - A screening urine test requiring a wet unstained urine sediment examination.

Nephritis - Inflammation of the kidney.

Nephrosis - A disease of the kidney, yielding increased glomerular membrane permeability for proteins and resulting in protein loss.


The routine urinalysis is carried out in three phases: macroscopic, chemical, and microscopic analysis.



1. Normal: various shades of yellow from pale straw, yellow, to amber
2. Significance:

  • Yellow shades – intensity of color usually related to concentration of specimen; yellow due mainly to urochrome, also to vitamin B6.
  • Red shades – erythrocytes, hemoglobin, porphyrins, drugs, foods (beets, red candy), myoglobin
  • Green to yellow-brown – suggests bilirubin (If you shake the urine, white foam = little or no bilirubin; yellow-brown = possibility of bilirubin)
  • Brown to black – old blood, hemosiderin, myoglobin, rhubarb, melanin, alkapton bodies, certain laxatives

3. Method of measurement: visual observation


1. Normal: wide range depending on concentration and method of collection. Normal specimens may be clear, hazy or cloudy depending on the cause of the turbidity which can only be established by microscopic analysis.
2. Causes:

  • Heavy concentration of crystals
  • Erythrocytes
  • Bacterial infection or contamination
  • Contamination by vaginal secretions
  • Leukocytes

3. Method of measurement: visual observation


1. Normal: aromatic
2. Causes:

  • Ammoniacal – bacterial breakdown of urea (e.g., by Proteus species); usually due to bacterial contamination in a specimen that is not fresh, but may be due to severe infection if found immediately after voiding.
  • Acetone (heavy, fruity sweetness) – ketosis
  • “Maple syrup” – hereditary maple syrup disease

3. Food odors (e.g., asparagus)


Specific gravity (Normal, 24-h: 1.010 – 1.025)

  1. Urinometer (hydrometer)
  2. Refractometer
  3. Dipsticks

Hydrogen ion concentration (pH)

Maximum physiological range: 4.5 – 8.0; Reference range for 24-hour specimen: 5.0 – 7.0

  1. pH papers
  2. Dipsticks


  1. Sulfosalicylic acid detects total proteins, some radio-opaque dyes, κ and λ light chains
  2. Dipsticks (detect albumin only). Test is based on protein error of indicators.
  3. Bence

-Jones protein (kappa, κ or lambda, λ) light chains]. Acid/heat precipitation at 56 degrees C. Immunofixation detects κ- and λ-chains.


  1. Clinitest tablets (detects reducing substances such as glucose, galactose, fructose, lactose, pentose, ascorbic acid, salicylates, homogentisic acid); (NOTE: sucrose is not a reducing sugar)
  2. Dipsticks specifically detect glucose with glucose oxidase reaction; (NOTE: Reducing agents such as ascorbic acid can quench reaction giving a false negative result)

Ketone bodies

  1. Dipsticks or reagent tablets (acetone, acetoacetate, NOT β-hydroxybutyrate)

Heme proteins (Hemoglobin, occult blood; Myoglobin)

  1. Guaiac test, modified
  2. Dipsticks (NOTE: Reducing agents such as ascorbic acid can quench reaction giving a false negative result. Also, at urine pH below 6.0, red cells are not lysed, and a false negative test may result.)

Bilirubin (Direct or conjugated bilirubin)

  1. Dipsticks or reagent tablets


  1. Dipsticks


Place 10 mL of well-mixed urine into a conical test tube and centrifuge for 4 minutes. To avoid resuspension of sediment, do not apply brake at the end of centrifugation. The centrifuge tube is inverted quickly but with a smooth motion of the wrist, and the supernatant is allowed to drain off without dislodging the button of sediment. The tube is returned to an upright position, and the sediment is resuspended by gently tapping the bottom of the tube with the fingers. A drop of sediment is then transferred onto a clean glass slide and covered with a cover slip.

The slide is then placed on the stage of the microscope and scanned under reduced light (by lowering the condenser) with the low power objective, in order to detect the larger elements, i.e., casts, mucous threads, parasites, ova, foreign bodies, etc. After scanning the entire slide, the number of elements counted in at least 10 low power fields are averaged for the final value. Casts, if present, are also examined under the high power field to determine their types.

The dry high power objective is then used to estimate the numbers of red cells, white cells, epithelial cells, bacteria, yeast, trichomonas, and crystals in 10 different fields, and an average count for each is recorded.

Urine Sediment

Casts. “Imprints” of renal tubules; examine and count under LPF
Cells (erythrocytes; leukocytes; squamous epithelial cells – urethra, vagina; transitional epithelial cells – bladder; renal tubular cells, etc.). Examine and count under HPF.
Artifacts (e.g., glass, dust, pollen, starch granules, hair, oil, plant fibers)

Urine Casts

Casts are found in the urine sediment. They are formed in two ways, by precipitation and gelling of proteins in tubular fluid, and by clumping of cells in tubules. Casts are molded in the lumen of the distal renal tubules or collecting ducts. The matrix of all casts is a specific mucoprotein common to all casts, namely Tamm-Horsfall protein. The classification of casts is based on appearance, physical properties, and type of cellular components. Cells within the matrix can degenerate into coarse and finely granular casts and to waxy casts.

Types of urine casts.

  1. Hyaline casts. The casts consist only of Tamm-Horsfall protein. They are excreted by the normal kidney in small amounts. Excretion of numerous casts is seen in all renal diseases.
  2. White blood cell (leukocyte) casts. These casts are formed when WBC’s are incorporated into the protein matrix. They enter the urine stream by ameboid movement through and between tubular epithelial cells and sometimes they cross the glomerular capillary lumen. These casts are associated with diseases with leukocytic exudation and interstitial inflammation. Example: Pyelonephritis.
  3. Red cell (erythrocyte) casts. Presence of these casts indicates severe injury to the glomerular basement membrane. The reddish orange color is secondary to hemoglobin pigmentation. Erythrocytes (RBC’s) are biconcave disks packed in fibrin meshwork within the cast matrix. These casts are associated with acute glomerulonephritis (most common), lupus nephritis, Goodpasture’s Syndrome, and subacute bacterial endocarditis (SBE).
  4. Renal epithelial casts. These casts are due to constant desquamation and renewal of the renal epithelium. Their presence points to a pathological process occurring in the kidney and affecting the tubular portion of the nephron (tubular damage). Epithelial casts are associated with exposure to nephrotoxic agents and exposure to viruses.
  5. Granular casts. These casts are formed from breakdown products of cellular casts and immunoglobulins. There is a progression from coarsely granular to finely granular casts.
  6. Waxy casts. These are the result of progressive degenerative changes occurring in cellular casts and they are associated with severe chronic renal disease and amyloidosis.
  7. Fatty casts. These casts are due to leakage of lipoproteins through the glomerulus (seen in nephrotic syndrome, diabetes mellitus, and with damaged renal epithelial cells).
  8. Mixed cell casts.

Urine Crystals

Some Commonly Seen Urinary Crystals
Crystal Appearance Urine pH
Calcium oxalates "Envelopes" acid
Sodium urates "Whetstones" acid
Triple phosphates(magnesium ammonium phosphate) "Coffin lids" alkaline
Ammoniumbiurates "Thorn apples" alkaline
Amorphous phosphates Amorphous debris alkaline
Tyrosine Needles in rosettes acid
Leucine Spheres acid
Sulfonamides Sheaves acid
Cystine Hexagons acid

Drug crystals (e.g., ampicillin needles, primidone hexagons) are formed from drugs that are present in relatively high concentrations and that are relatively insoluble in water at the urinary pH.


Hemoglobin and Myoglobin

Both are heme-containing proteins and have peroxidase properties. Hence, they react with Hemastix and Labstix for “blood.” (See “Detection of Occult Blood” for an explanation of the test). The following methods are most common:

  1. Ammonium sulfate precipitation tests (not sufficiently sensitive).
  2. Spectrophotometric methods
  3. Immunoassay methods
  4. Ultrafiltration methods. Differentiation of myoglobin from hemoglobin is based on their different molecular weights. Myoglobin is a monomer of approximate MW 16,000; hemoglobin is a tetramer of MW 64,458.
  5. Combinations of the above

Myoglobinuria is seen in:

  1. Crushing injuries
  2. Electrocution
  3. Clostridium welchii (C. perfringens) infections
  4. Necrosis of muscle due to sustained pressure (rhabdomyolysis)
  5. Strenuous exercise
  6. Certain genetic defects

Myoglobin, due to its low molecular weight, is readily excreted by the kidney and concentrated in the urine. Large amounts of myoglobin are toxic to the renal tubular cells. Thus, prolonged, severe myoglobinuria may lead to renal shutdown. However, hemoglobin itself is much less nephrotoxic.


Urine is orange-green
Foam is brownish or brownish-green
Only water-soluble bilirubin, conjugated with glucuronic acid (direct-reacting) is excreted into the urine. Bilirubin is found in the urine in:

  1. Obstruction of biliary system
  2. Hepatocellular damage

Urinary bilirubin is important in early detection of jaundice and differential diagnosis of jaundice. (See Laboratory Diagnosis of Liver Disease).

Note: Bilirubin is not found in urine in hemolytic disease, which leads to increase in unconjugated albumin-bound (indirect-reacting) bilirubin which is not excreted by the kidney.


It is formed by action of bacteria on conjugated bilirubin in the gut. Subsequently it is partially reabsorbed and excreted by the liver and kidney.

Increased in:

  1. Hemolytic anemia
  2. Early parenchymal liver disease

Decreased in:

  • Obstruction of extrahepatic bile ducts (particularly in carcinoma of head of pancreas).
  • If the stool is chalky white, as in complete obstruction, no urobilin (stercobilin) is present.


Brown urine; urine may darken on standing
Melanin and melanogen are excreted in urine of patients with metastatic melanomas
Melanogen is a precursor of melanin


Thormählen’s test: Melanogen reacts with ferric chloride to give a brown to black color.

Serotonin and 5-HIAA (5-Hydroxyindoleacetic Acid)

Serotonin is normally produced by the argentaffin cells of the intestines. It is largely carried in the blood by platelets. Serotonin is metabolized to 5-HIAA which is excreted in the urine.

In carcinoid tumors (argentaffinomas), serotonin (and therefore 5-HIAA) is produced in excess.

Collect 24 h urine (acidified with HCl)
Request quantitative test for 5-HIAA
Normal excretion: 1-5 mg/d
Patients with carcinoid tumors excrete 40-350 mg of 5-HIAA/d
Drug interferences with test: Phenothiazines
Dietary interferences: Walnuts and bananas

Alkaptonuria (Ochronosis)

A condition in which there is excretion of homogentisic acid in urine


  1. The Clinitest tablet gives a positive result in presence of reducing substances.
  2. The urine darkens on alkalinization and heating or standing.


Found as free granules or in epithelial cells, macrophages and casts
Test: Prussian blue reaction on sediment

Found in:

  • Conditions of prolonged hemoglobinuria or myoglobinuria
  • Pernicious anemia, chronic hemolytic anemia, multiple transfusions, paroxysmal nocturnal hemoglobinuria, hemochromatosis

Laboratory Diagnosis of Pheochromocytoma and Neuroblastoma

Dopamine, epinephrine and norepinephrine (catecholamines) may be produced in large amounts by these tumors. Epinephrine and norepinephrine are catabolized to their physiologically inactive 3-methoxy derivatives (metanephrines). The metanephrines are further catabolized by monoamine oxidase (MAO) to 3-methoxy-4-hydroxymandelic acid (vanillylmandelic acid, VMA), which is the major metabolite in pheochromocytoma.

% Metabolite
VMA ~75%
Metanephrine ~10%
Catecholamines ~1%

Homovanillic acid (HVA) is the major metabolite in neuroblastoma.

Because of derangements of these metabolic pathways in the tumors, these ratios of excretion may vary in patients afflicted with these tumors.

Laboratory Workup of Pheochromocytoma and Neuroblastoma

1. Urinary VMA: Collect 24 hour urine in 15 mL of concentrated HCl. Normal values: 10-15 mg/d. More than 90% of all patients with pheochromocytoma have intermittent or continuous elevation of urinary VMA.
Dietary and drug restrictions are necessary for this test: No bananas, coffee, tea, many drugs including aspirin. Best approach is to keep the patient off any drugs while collecting urine for this test.
2. Total metanephrine assay: Collect 24 hour urine preserved with 15 mL of HCl.
Normal: Up to 1 mg/d.
98% of all patients with pheochromocytoma have elevated urinary metanephrines. However, elevations are also seen in severe stress, shock, sepsis, metastatic disease.
MAO inhibitors increase excretion of metanephrines.

3. Plasma catecholamines, fractionation.

4. HVA in urine: suspected neuroblastoma.

In problem cases as well as in patients in whom neuroblastoma is suspected, request urinary
catecholamines, homovanillic acid (HVA) and/or dopamine determinations.

Major Synthetic and Catabolic pathways of Epinephrine and Norepinephrine




The detection of blood in feces is an important diagnostic aid in establishing the occurrence of internal bleeding resulting from gastrointestinal malignant growths or from gastric and duodenal ulcers. Severe gastrointestinal bleeding (60-90 mL blood per day) is visually recognizable because “tarry” (black) stools are excreted and further microscopic examination of these stools reveals the presence of erythrocytes. In those instances where much smaller quantities of blood are not visually or microscopically apparent, more sensitive techniques are required to detect this hidden, or so-called “occult,” blood. Because heme-containing substances possess peroxidase activity, this property can be used to detect the presence of occult blood in feces or urine. Colorless, aromatic substances (such as guaiacol, o-tolidine, di-orthoanisidine) are catalytically oxidized to blue chromogens by heme in the presence of H2O2 when the reaction is performed in an acid medium. The sensitivity of the test is adjusted in such a way that a physiologic amount of blood loss will not give a positive reaction.


Guaiacol (o-methoxyphenol) is the usual substrate of choice. The same test may be used for occult blood in urine.

To establish that occult blood in feces is due to gastrointestinal hemorrhages, other possible sources of blood from hemorrhoids, menstrual flow, ingested blood derived from the nose or mouth, and perianal bleeding must be excluded. In addition, ingested meat contains hemoglobin and myoglobin and the presence of heme in stool derived from these foodstuffs may give false positive tests for fecal occult blood. Thus, for best results patients should be placed on meat-free or low-meat diets for three days before evaluation for occult blood in their stools. Normally, up to 1.5 mL of blood may be lost daily in the stools. Drugs (such as salicylates, steroids, reserpine, indomethacin, colchicine, iron) often cause gastrointestinal blood loss, resulting in positive occult blood tests. Potent reducing agents such as ascorbic acid may quench the reaction (false negative). False positives may be seen following ingestion of horseradish (peroxidase). To reduce the number of false negative results, the test should be requested on several different occasions.


Case 1

A 65-year-old man notes progressive swelling of his lower extremities as well as the onset of severe back pain. A urinalysis performed in his physician’s office gives the following results:

Appearance clear, light yellow
Specific gravity 1.030
pH 6.3
Glucose negative
Ketones negative
Bile negative
Protein negative to trace
Blood negative
Hyaline casts 0-1/LPF

A sulfosalicylic acid test subsequently performed is 4+ positive.

  1. Interpret the positive sulfosalicylic acid test in view of the negative Labstix test for protein.
  2. What is the differential diagnosis?
  3. What additional tests should be performed?
  4. Why is the specific gravity high?

Case 2

A 33-year-old diabetic woman is surprised to find that her Clinitest is 4+ positive, while a dipstick test is negative for glucose and for ketones. She is presently having a menstrual period and is also surprised to find that her blood-tinged urine is Labstix-negative for blood.

Discuss possibilities for these observations.

Crystals and Casts in Urine

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