Urine

Question 1

What is specific gravity?

Answer 1

A measure of the concentration of solutes in urine

Specific gravity indicates the kidney’s ability to concentrate or dilute urine.

Question 2

What is the normal pH range of urine on an average diet?

Answer 2

5.5 to 6.5

pH can vary based on metabolic status.

Question 3

How is osmolality defined?

Answer 3

A solution that has 1 osmole of solute dissolved in a kilogram of water

Osmolality in urine and serum plasma is measured using an osmometer.

Question 4

What are the two main categories of urine constituents?

Answer 4

Organic and inorganic substances

These are tested separately in chemical examinations.

Question 5

What is urea and its significance?

Answer 5

A product of protein metabolism synthesized in the liver

Question 6

What is the reference range for urea in urine?

Answer 6

20 - 30 g/d

This indicates normal levels of urea present in urine.

Question 7

What happens in the sodium hypobromite test for urea?

Answer 7

Urea reacts with alkaline sodium hypobromite to produce N2, visible as effervescence

This reaction can also be quantitatively measured using a ureometer.

Question 8

What is the chemical reaction involved in the sodium hypobromite test?

Answer 8

CONH2 + 3NaOH → N2 + Na2CO3 + 3NaBr

This equation represents the reaction of urea with sodium hypobromite.

Question 9

What is the procedure for the sodium hypobromite test

Answer 9

Add 4-5 drops of sodium hypobromite to 5 ml of urine in a test tube

A brisk effervescence indicates the presence of urea.

Question 10

What does the specific urease test indicate?

Answer 10

Presence of urea in the urine

The reaction produces NH3 and carbonic acid, leading to an alkaline environment.

Question 11

What color does phenolphthalein turn in an alkaline medium?

Answer 11

Pink

This color change indicates the presence of ammonia from urea breakdown.

Question 12

What are the two labeled test tubes used in the urease test?

Answer 12

T (test) and C (control)

Question 13

What is added to both test tubes in the urease test?

Answer 13

2 ml of urease suspension

Question 14

What is the purpose of heating the control tube in the urease test?

Answer 14

To inactivate the enzyme urease

Question 15

What indicators are used in the urease test?

Answer 15

5 ml of urea solution and 2 drops of phenolphthalein indicator

Question 16

What does a pink color in the test solution indicate in the urease test?

Answer 16

The presence of urea in normal urine

Question 17

What is uric acid?

Answer 17

The end product of purine metabolism

Question 18

What is the normal reference range of uric acid in urine on a purine-restricted diet?

Answer 18

0.3-0.5 gm daily

Question 19

What is the normal reference range of uric acid in urine on a purine-rich diet?

Answer 19

0.6 - 0.7 gm

Question 20

What is the principle of the phosphotungstic acid test for uric acid?

Answer 20

Uric acid is a reducing substance in an alkaline medium

Question 21

What color develops in the phosphotungstic acid test indicating the presence of uric acid?

Answer 21

Blue color

Question 22

What is creatinine?

Answer 22

An anhydride of the muscle creatine

Question 23

What is the normal daily excretion range of creatinine?

Answer 23

1-2 gm

Question 24

What is the principle of Jaffe’s test for creatinine?

Answer 24

Creatinine reacts with alkaline picrate solution to form an orange complex

Question 25

What color indicates the presence of creatinine in the Jaffe's test?

Answer 25

Orange color

Question 26

What is urobilinogen formed from?

Answer 26

Bacterial action on conjugated bilirubin in the intestine

Question 27

What happens to urobilinogen when exposed to air?

Answer 27

It is converted to urobilin, which darkens feces

Question 28

What is the principle of the test for urobilinogen using Ehrlich's reagent?

Answer 28

Urobilinogen reacts with Ehrlich's reagent to give a red color

Question 29

What indicates the presence of urobilinogen in normal urine during the test?

Answer 29

A red color seen when viewed through the mouth of the test tube

Question 30

What does an immediate or very intense red color after adding Ehrlich's reagent indicate?

Answer 30

Excess urobilinogen, which is abnormal

Question 31

What type of urine sample should be used for the urobilinogen test?

Answer 31

Freshly voided urine sample

Question 32

What happens to urinary urobilinogens on standing?

Answer 32

They get oxidized to urobilin

Question 33

What are ethereal sulphates?

Answer 33

Organic sulphates ## Footnote Ethereal sulphates are excreted in urine, primarily derived from dietary sulfur.

Question 34

What percentage of total sulfur is excreted as organic sulphates?

Answer 34

5-15% ## Footnote Organic sulphates include conjugated phenol and phenolsulphuric acid.

Question 35

What percentage of total sulfur is excreted as inorganic sulphates?

Answer 35

85-95% ## Footnote Inorganic sulphates are the major form of sulfur excretion in urine.

Question 36

What is the principle behind the test for ethereal sulphates?

Answer 36

Hot hydrochloric acid hydrolyses ethereal sulphates to inorganic sulphates ## Footnote The inorganic sulphates are then precipitated out with barium chloride.

Question 37

What is the procedure for testing ethereal sulphates?

Answer 37

Add 2 ml BaCl2 to 5 ml of urine, filter, then boil one portion with HCl and BaCl2 ## Footnote A turbid solution indicates the presence of ethereal sulphates.

Question 38

What indicates the presence of ethereal sulphates in normal urine?

Answer 38

The solution turns turbid upon boiling ## Footnote A light red color may also be seen.

Question 39

What are chlorides primarily related to in urine?

Answer 39

The content of food ingested ## Footnote On average, daily output is about 10-15 gms as NaCl.

Question 40

What is the principle behind the test for chlorides?

Answer 40

Chlorides are precipitated as silver salt with silver nitrate in the presence of nitric acid ## Footnote This is a common method for detecting chlorides in urine.

Question 41

What observation indicates the presence of chlorides in normal urine?

Answer 41

Formation of a white precipitate of silver chloride ## Footnote This occurs when adding AgNO3 to the urine sample.

Question 42

What is the procedure for testing inorganic sulphates?

Answer 42

Add 2 ml of BaCl2 to 2 ml of urine ## Footnote A curdy white precipitate indicates the presence of sulphates.

Question 43

What indicates the presence of inorganic sulphates in normal urine?

Answer 43

A curdy white precipitate of barium sulphate ## Footnote This is the result of the precipitation reaction with barium chloride.

Question 44

What is the daily output of calcium in urine?

Answer 44

0.1-0.3 gms ## Footnote The output is influenced by dietary intake.

Question 45

What is the average total output of phosphates in urine?

Answer 45

About 1 gm ## Footnote Phosphate excretion is highly dependent on diet.

Question 46

Fill in the blank: The amount of chlorides excreted in urine is related primarily to the content of _______.

Answer 46

food ingested

Question 47

What white precipitate is formed when calcium combines with potassium oxalate in acidic conditions?

Answer 47

Calcium oxalate ## Footnote This reaction occurs under acidic conditions.

Question 48

What color precipitate do phosphates in urine form when warmed with ammonium molybdate in the presence of nitric acid?

Answer 48

Canary yellow precipitate ## Footnote This precipitate is ammonium phosphomolybdate.

Question 49

What is the first step in testing for calcium in urine?

Answer 49

Add a few drops of phenolphthalein to 10 ml of urine ## Footnote This is followed by adding ammonia solution until a pink color develops.

Question 50

What is the chemical formula for the precipitate that forms from calcium phosphate in alkaline conditions?

Answer 50

Ca3(PO4)2 ## Footnote This precipitate is formed when urine becomes alkaline.

Question 51

What should be done after filtering the calcium phosphate precipitate?

Answer 51

Wash down the precipitate with 5 ml of boiling 2% acetic acid ## Footnote This helps dissolve the precipitate for further testing.

Question 52

What indicates the presence of calcium in normal urine during the calcium test?

Answer 52

A white precipitate of calcium oxalate ## Footnote This occurs when 5 drops of 1% acetic acid and 5 ml of ammonium oxalate are added.

Question 53

What is the procedure to test for phosphate in urine?

Answer 53

Add 0.5 ml of concentrated HNO3 and 2 ml of ammonium molybdate to 2 ml of the solution ## Footnote This will result in a canary yellow precipitate if phosphate is present.

Question 54

What is the normal daily output of ammonia in urine?

Answer 54

0.5 - 0.8 grams ## Footnote This output can increase with the intake of acid-forming foods.

Question 55

What is the principle behind the ammonia test in urine?

Answer 55

NH3 gas is liberated when urine containing ammonia is boiled under alkaline conditions ## Footnote This indicates the presence of ammonium ions.

Question 56

What should be added to urine to make it alkaline before boiling for the ammonia test?

Answer 56

2% Na2CO3 ## Footnote This makes the solution alkaline to litmus or turns pink with phenolphthalein.

Question 57

What observation indicates the presence of NH4+ in normal urine?

Answer 57

The filter paper turns pink ## Footnote This occurs when a filter paper dipped in phenolphthalein is held at the mouth of the test tube while boiling.

Question 58

Normal daily value of chloride in urine?

Answer 58

On average, daily output is about 10-15 gms as NaCl.