Urine Flashcards
What is specific gravity?
A measure of the concentration of solutes in urine
Specific gravity indicates the kidney’s ability to concentrate or dilute urine.
What is the normal pH range of urine on an average diet?
5.5 to 6.5
pH can vary based on metabolic status.
How is osmolality defined?
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.
What are the two main categories of urine constituents?
Organic and inorganic substances
These are tested separately in chemical examinations.
What is urea and its significance?
A product of protein metabolism synthesized in the liver
What is the reference range for urea in urine?
20 - 30 g/d
This indicates normal levels of urea present in urine.
What happens in the sodium hypobromite test for urea?
Urea reacts with alkaline sodium hypobromite to produce N2, visible as effervescence
This reaction can also be quantitatively measured using a ureometer.
What is the chemical reaction involved in the sodium hypobromite test?
CONH2 + 3NaOH → N2 + Na2CO3 + 3NaBr
This equation represents the reaction of urea with sodium hypobromite.
What is the procedure for the sodium hypobromite test
Add 4-5 drops of sodium hypobromite to 5 ml of urine in a test tube
A brisk effervescence indicates the presence of urea.
What does the specific urease test indicate?
Presence of urea in the urine
The reaction produces NH3 and carbonic acid, leading to an alkaline environment.
What color does phenolphthalein turn in an alkaline medium?
Pink
This color change indicates the presence of ammonia from urea breakdown.
What are the two labeled test tubes used in the urease test?
T (test) and C (control)
What is added to both test tubes in the urease test?
2 ml of urease suspension
What is the purpose of heating the control tube in the urease test?
To inactivate the enzyme urease
What indicators are used in the urease test?
5 ml of urea solution and 2 drops of phenolphthalein indicator
What does a pink color in the test solution indicate in the urease test?
The presence of urea in normal urine
What is uric acid?
The end product of purine metabolism
What is the normal reference range of uric acid in urine on a purine-restricted diet?
0.3-0.5 gm daily
What is the normal reference range of uric acid in urine on a purine-rich diet?
0.6 - 0.7 gm
What is the principle of the phosphotungstic acid test for uric acid?
Uric acid is a reducing substance in an alkaline medium
What color develops in the phosphotungstic acid test indicating the presence of uric acid?
Blue color
What is creatinine?
An anhydride of the muscle creatine
What is the normal daily excretion range of creatinine?
1-2 gm
What is the principle of Jaffe’s test for creatinine?
Creatinine reacts with alkaline picrate solution to form an orange complex
What color indicates the presence of creatinine in the Jaffe’s test?
Orange color
What is urobilinogen formed from?
Bacterial action on conjugated bilirubin in the intestine
What happens to urobilinogen when exposed to air?
It is converted to urobilin, which darkens feces
What is the principle of the test for urobilinogen using Ehrlich’s reagent?
Urobilinogen reacts with Ehrlich’s reagent to give a red color
What indicates the presence of urobilinogen in normal urine during the test?
A red color seen when viewed through the mouth of the test tube
What does an immediate or very intense red color after adding Ehrlich’s reagent indicate?
Excess urobilinogen, which is abnormal
What type of urine sample should be used for the urobilinogen test?
Freshly voided urine sample
What happens to urinary urobilinogens on standing?
They get oxidized to urobilin
What are ethereal sulphates?
Organic sulphates
Ethereal sulphates are excreted in urine, primarily derived from dietary sulfur.
What percentage of total sulfur is excreted as organic sulphates?
5-15%
Organic sulphates include conjugated phenol and phenolsulphuric acid.
What percentage of total sulfur is excreted as inorganic sulphates?
85-95%
Inorganic sulphates are the major form of sulfur excretion in urine.
What is the principle behind the test for ethereal sulphates?
Hot hydrochloric acid hydrolyses ethereal sulphates to inorganic sulphates
The inorganic sulphates are then precipitated out with barium chloride.
What is the procedure for testing ethereal sulphates?
Add 2 ml BaCl2 to 5 ml of urine, filter, then boil one portion with HCl and BaCl2
A turbid solution indicates the presence of ethereal sulphates.
What indicates the presence of ethereal sulphates in normal urine?
The solution turns turbid upon boiling
A light red color may also be seen.
What are chlorides primarily related to in urine?
The content of food ingested
On average, daily output is about 10-15 gms as NaCl.
What is the principle behind the test for chlorides?
Chlorides are precipitated as silver salt with silver nitrate in the presence of nitric acid
This is a common method for detecting chlorides in urine.
What observation indicates the presence of chlorides in normal urine?
Formation of a white precipitate of silver chloride
This occurs when adding AgNO3 to the urine sample.
What is the procedure for testing inorganic sulphates?
Add 2 ml of BaCl2 to 2 ml of urine
A curdy white precipitate indicates the presence of sulphates.
What indicates the presence of inorganic sulphates in normal urine?
A curdy white precipitate of barium sulphate
This is the result of the precipitation reaction with barium chloride.
What is the daily output of calcium in urine?
0.1-0.3 gms
The output is influenced by dietary intake.
What is the average total output of phosphates in urine?
About 1 gm
Phosphate excretion is highly dependent on diet.
Fill in the blank: The amount of chlorides excreted in urine is related primarily to the content of _______.
food ingested
What white precipitate is formed when calcium combines with potassium oxalate in acidic conditions?
Calcium oxalate
This reaction occurs under acidic conditions.
What color precipitate do phosphates in urine form when warmed with ammonium molybdate in the presence of nitric acid?
Canary yellow precipitate
This precipitate is ammonium phosphomolybdate.
What is the first step in testing for calcium in urine?
Add a few drops of phenolphthalein to 10 ml of urine
This is followed by adding ammonia solution until a pink color develops.
What is the chemical formula for the precipitate that forms from calcium phosphate in alkaline conditions?
Ca3(PO4)2
This precipitate is formed when urine becomes alkaline.
What should be done after filtering the calcium phosphate precipitate?
Wash down the precipitate with 5 ml of boiling 2% acetic acid
This helps dissolve the precipitate for further testing.
What indicates the presence of calcium in normal urine during the calcium test?
A white precipitate of calcium oxalate
This occurs when 5 drops of 1% acetic acid and 5 ml of ammonium oxalate are added.
What is the procedure to test for phosphate in urine?
Add 0.5 ml of concentrated HNO3 and 2 ml of ammonium molybdate to 2 ml of the solution
This will result in a canary yellow precipitate if phosphate is present.
What is the normal daily output of ammonia in urine?
0.5 - 0.8 grams
This output can increase with the intake of acid-forming foods.
What is the principle behind the ammonia test in urine?
NH3 gas is liberated when urine containing ammonia is boiled under alkaline conditions
This indicates the presence of ammonium ions.
What should be added to urine to make it alkaline before boiling for the ammonia test?
2% Na2CO3
This makes the solution alkaline to litmus or turns pink with phenolphthalein.
What observation indicates the presence of NH4+ in normal urine?
The filter paper turns pink
This occurs when a filter paper dipped in phenolphthalein is held at the mouth of the test tube while boiling.
Normal daily value of chloride in urine?
On average, daily output is about 10-15 gms as NaCl.
