Errors of Amino Acid Metabolism 1. Cystinuria: Positive cyanide-nitroprusside test. Cystine crystals in urine. 2. Fanconi’s syndrome: Positive glucose-oxidase test.

 

Normally present in urine: elevated levels

may indicate liver abnormalities or excessive

destruction of RBC’s, e.g. in homolytic anemia.

urobilinogen should be considered alongside

billirubin as a differential diagnosis

Protein A positive result indicates renal disease, raised

blood pressure or urinary tract infection

pH Normal range 4 to 6. A pH above 7 suggests

states urine unsuitable for testing

Blood Presence in urine suggests serious renal or

urological disease, or renal tract infection

Specific

gravity

Monitors the concentrating and diluting power of

the kidney. Assists in the interpretation of other

tests

Ketone May indicate uncontrolled diabetes or a reduced

carbohydrate diet

Bilirubin

(10SG only)

Indicative of hepatic or biliary disease. Bilirubin

may appear in urine before other signs of

abnormality are apparent

Glucose The most important cause of glucose in urine is

diabetes mellitus

FIG. 5.11: Clinitek 50: The instrument

(Courtesy: Siemens Medical Solutions)

There’s no denying easy chemistry. ¾ Multistix GP

¾ Clinitek microalbumin

¾ Clinitest hCG.

Clinitek® 50 Urine Analyzer (Fig. 5.11)

Dependable Results in Any Patient Setting

Combined with the Bayer market leading urinalysis strips,

Multistix, the Bayer Clinitek 50 provides the complete

urinalysis solution. Suitable for use in a wide range patient

settings, the Clinitek 50 provides on the spot, accurate

results that allowing on the spot clinical decisions.

Easy to Use

1. Dip reasgent strip into sample and press start button

(Fig. 5.12)

2. Blot side of reagent strip and place strip on instrument

feed table (Fig. 5.13)

3. Instrument analyzes, displays abnormally and prints

results at the rate of one test per minute (Fig. 5.14).

A Helping Hand

¾ The Clinitek 50 requires only 10 seconds of operators

time, meaning you can get on with caring for your

patient whilst the instrument does the test.

User Friendly

¾ Display prompts make the Clinitek 50 intuitive and

easy to use.

Urine Analysis 81

FIG. 5.13: Place reagent strip on the instrument feed table

FIG. 5.15: Clinitek 500 urinalysis instrument

FIG. 5.12: Dip the reagent strip FIG. 5.14: The instrument with printout

Rapid Results

¾ Fast, reliable results available in 1 minute, giving a

printed record of the patients results.

Improved Use of Resources

Screens out non-infected urine samples so that only the

positives need to be referred for laboratory follow-up

(Fig. 5.9).

A Wide Range of Test Parameters

Clinitek 50 is suitable for use with;

¾ Multistix lOSG Multistix 8SG

¾ Multistix GP

¾ Clinitek Microalbumin

¾ See Figure 5.10 for etiological basis of positive results

obtained.

Clinitek® 500 Urinalysis Instrument

In combination with the Bayer market leading, Multistix®

range, the Clinitek® 500 enables automated reading of strips

in high throughout settings (Fig. 5.15). Complimented

by a user friendly interface and comprehensive data

management it provides a discrete platform offering

accuracy of results and efficiency in workflow.

82 Concise Book of Medical Laboratory Technology: Methods and Interpretations Efficiency in Processing

¾ 1 strip processed every 7 seconds

¾ 1 result every minute

¾ Strip needs only to be placed in analyzer platform.

Continuous “load and capture”mechanism draws strip

into reader

¾ Strip automatically discarded into waste tray after

processing

¾ Barcode reader for data entry.

User Friendly

• Easy to read touch screen display

• Operator screen guidance for processing

• Barcode reader for data entry.

Intelligent Data Management

¾ Accurate identification and flagging of abnormal data

¾ Two screening functions—confirmatory and microscopic

¾ Customizable testing and reporting to meet local needs

¾ Memory storage of 500 patient results and 200 control

results.

¾ Flexible reporting options

• Internal data storage

• Transfer via RS232 port

• Print using on board printer

• Send to external printer.

¾ Operator and patient ID facility.

A Wide Range of Test Parameters

Clinitek® 500 is suitable for use with:

• Multistix 1OSG

• Multistix 8SG

• Multistix GP.

SPECIAL URINE TESTS

Calcium in Urine (Sulkowitch Test)

Fasting or random samples may be tested. Before the

test, the patient should be on neutral low-calcium diet for

3 days. Collect 24 hours urine specimen. Mix equal parts

of urine and Sulkowitch reagent, let stand for 2–3 minutes

and read as under.

0 = No precipitate, no urine calcium; serum

calcium level 5–7.5 mg%.

1+ = Fine white cloud, normal urine and blood

calcium level.

2+ and 3+ = Thicker, coarser precipitate, raised urinary

calcium.

4+ = Precipitate like milk, strongly positive.

Normal Values

• 24 hours levels

• 100–250 mg/24 hours on average diet

• < 150 mg/24 hours on low calcium diet.

Most of the calcium discharged by the body is excreted

via stool. However, there is a small quantity of calcium

that is normally excreted in the urine, this varies with the

variation in dietary calcium. The 24 hours test is most often

required to determine the function of the parathyroid

gland, which maintains a balance between calcium and

phosphorus by means of parathormone.

Calcium in urine can also be estimated by using regular

serum biochemistry tests—OCPC or Arsenazo method.

Clinical Relevance

Increased Levels

1. Caused by:

• Hyperparathyroidism (results in constant 3 + to

4 + Sulkowitch test).

• Sarcoidosis

• Primary cancers of breast and lung

• Metastatic malignancies

• Myeloma with bone metastasis

• Wilson’s disease

• Renal tubular acidosis

• Glucocorticoid excess.

2. Increased urinary calcium usually accompanies

elevated blood calcium levels.

3. Calcium excretion greater than intake is always

excessive, and excretion above 400–500 mg/24 h is

reliably abnormal.

4. Increased levels of calcium occur whenever calcium is

mobilized from the bone, as in metastatic cancer and

prolonged skeletal mobilization.

5. When calcium is excreted in increasing amounts, a

potential for nephrolithiasis or nephrocalcinosis is

created.

Decreased Levels

Caused by:

1. Hypoparathyroidism (hypocalcemia caused by

hypoparathyroidism is usually associated with a

negative reaction).

2. Vitamin D deficiency (vitamin D is essential for

absorption of calcium).

3. Malabsorption syndrome.

Interfering Factors

a. Falsely high values are seen in:

• High sodium and magnesium intake

• Very high milk intake

Urine Analysis 83

• Levels are often high immediately after meals

• Drugs:

– Androgens

– Cholestyramine

– Vitamin D

– Parathyroid injection

– Nandrolone, in some cancer patients.

B. False negative (lowered) values are seen in

• Increased dietary phosphate

• Alkaline urine

• Drugs:

– Sodium phytate

– Thiazides

– Viomycin.

Be Careful

1. Urine calcium test is not a substitute for serum

calcium, it can, however, be done in an emergency.

Hypercalcemia can be life threatening.

2. Low urinary calcium patients should be observed for

tetany.

3. The first sign of calcium imbalance may be the

occurrence of pathological fractures that can be related

to calcium excess.

Serotonin (5-Hydroxytryptamine)

Carcinoids

Carcinoids: (Argentaffinomas) may produce serotonin,

which is metabolized to 5-hydroxy-indole acetic acid (5-

HIAA). Presence of this compound in urine in more than

traces indicates malignant carcinoid metastatic to the liver.

Test

Acidify 2 mL of filtered urine with 2 drops of 10% HCl and

extract twice with 20–25 mL of ether. Evaporate the dry

residue in 1 mL of 0.1 N HCl. Add 1 mL Ehrlich’s reagent.

Boil for 2–3 minutes. A distinct blue color indicates the

presence of 5-HIAA in abnormal amounts in urine.

Normal Values

Qualitative— Negative

Quantitative— 2–10 mg/24 h.

60–100 mEq/24 h.

For screening purposes, a random test may be enough.

Serotonin is a vasoconstricting hormone produced

normally by argentaffin cells of the GI tract. The principal

function of the cells is to regulate smooth muscle

contraction and peristalsis. In carcinoid tumor (tumor of

the argentaffin cells), there is rise in levels of 5-hydroxyindoleacetic acid (5-HIAA), which happens to be a

denatured product of serotonin.

Method

1. No bananas, pineapples, tomatoes, eggplants, or

avocados to be consumed during the 24 hours test

because they contain serotonin.

2. A 24 hours urine container with preservative is labeled

with the name of patient, test and date.

3. General instructions for 24 hours sample collection

are observed.

Clinical Relevance

1. Levels in excess of 100 mg per 24 hours are indicative

of large carcinoid tumor, especially when metastatic.

However, this increase is found only in 5–7% cases of

carcinoid tumors.

2. Levels between 10 mg and 100 mg per 24 hours may

be seen in:

• Hemorrhage

• Thrombosis

• Nontropical sprue

• Severe pain of sciatica or skeletal and smooth

muscle spasm.

Interfering Factors

False positives:

1. Bananas, pineapples, plums, walnut, and avocados

may increase 5-HIAA levels, for all of them contain

serotonin.

2. Drugs that may lead to false-positive result

• Acetanilide

• Acetophenetidin

• Caffeine

• Glyceryl guaiacolate

• Fluorouracil (5 FU)

• Mephenesin

• Melphalan

• Methocarbamol

• Methamphetamine

• Reserpine

• Phenacetin solution

• Lugol’s iodine

• Phenmetrazine

• Methysergide maleate.

False negatives:

Drugs that may falsely decrease 5-HIAA levels:

¾ ACTH

¾ Chlorpromazine

84 Concise Book of Medical Laboratory Technology: Methods and Interpretations ¾ Heparin

¾ Imipramine

¾ Isoniazid

¾ MAO inhibitor

¾ Methenamine mandelate

¾ Methyldopa

¾ Phenothiazines

¾ Promethazine

¾ P-chlorophenylaniline.

Ideally, the patient should take no drugs for 72 hours

prior to test if possible.

Cystine

To 5 mL of urine, add 2 mL of 5% sodium cyanide

solution and let them react for 10 minutes. Add 5 drops

of 5% sodium nitroprusside solution and mix thoroughly.

Cystine produces a magenta color. If no cystine is present,

a pale brown or pale pink color results. All solutions should

be freshly prepared. Also, examine the urinary sediment

for cystine crystals. Urinary cystine is raised in cystinurias.

Normal values

Qualitative : Negative

Quantitative : Children under 8 years:

 2–13 mg/24 h.

Individuals above 8 years : 7–28 mg/h.

These tests of urine are useful in the differential

diagnosis of cystinuria, an inherited disease from

cystinosis. Cystinuria is a hereditary disease, characterized

by bladder calculi. In cystinosis, cystine is deposited in

lung tissues.

Clinical Relevance

Values are Increased in

1. Cystinuria (up to 20 times normal) in which there

is excessive urinary excretion of lysine, ornithine,

arginine, and cystine.

2. Cystinosis (no excess of lysine, arginine or ornithine).

Fat in Urine

Take equal parts of urine and ether, cloudiness due to fat

disappears, decant ether onto a watch glass, evaporate, fat

leaves a greasy deposit. Fat may be seen microscopically.

Hereditary Metabolic Disorders

Errors of Carbohydrate Metabolism

1. Galactosuria: Positive test for reducing substance

(Benedict’s qualitative). Negative glucose-oxidase test.

Positive phloroglucinol test.

2. Pentosuria: Positive Benedict’s qualitative test.

Negative glucose-oxidase test. Positive orcinyl-HCl

test.

3. Fructosuria: Positive Benedict’s test. Negative glucoseoxidase test. Positive resorcinol-HCl test (Seliwanoff).

Errors of Amino Acid Metabolism

1. Cystinuria: Positive cyanide-nitroprusside test. Cystine

crystals in urine.

2. Fanconi’s syndrome: Positive glucose-oxidase test.

Paper chromatography for amino acids.

3. Wilson’s disease: Positive glucose-oxidase test. Paper

chromatography for amino acids.

4. Phenylketonuria: Positive ferric chloride test.

5. Hartnup disease: Paper chromatography.

6. Alkaptonuria (Homogentisic acid): Positive Benedict’s

test. Urine darkens on standing. Negative glucoseoxidase test. Urine reduces silver on sensitized plate.

7. Tyrosinosis: Paper chromatography. Positive Millon test.

8. Maple syrup disease: Maple syrup odor of urine. Paper

chromatography.