Urine Analysis: Common Questions

Copper sulphate, sodium carbonate, sodium citrate and distilled water.

Also called as lag storage glycosuria. After a meal, there is rapid intestinal absorption of glucose leading to transient elevation of blood glucose above renal threshold. This can occur in persons with gastrectomy or gastrojejunostomy and in hyperthyroidism. Fasting and 2 hours’ glucose will be normal.

Diabetes mellitus with nodular glomerulosclerosis results in nephrotic syndrome. Uncontrolled diabetes mellitus leads to ketoacidosis and ketonuria in addition.

a. Cushing’s syndrome
b. Hyperthyroidism
c. Pheachromocytoma
d. Pancreatic cancer
e. Acromegaly. 

The three ketone bodies are Acetone, acetoacetic acid and beta hydroxyl butyric acid.
The causes of ketonuria are as under
a. Diabetic ketoacidosis
b. Starvation and vomiting
c. Strenuous exercise
d. Malabsorption.

Urobilinogen is extracted in chloroform (after adding saturated solution of sodium acetate- pink color) while phorphobilinogen cannot be extracted in chloroform – Watson Schwartz test.

Only conjugated urine is excreted by kidney. Therefore, it is detected in obstructive jaundice and hepatocellular jaundice.

Urine is usually dark brown because of the conversion of hemoglobin to acid hematin ( in acidic urine). Very dark color resembles cola color

Presence of three or more number of red cells per high power field on microscopic examination in two out of three properly collected samples. No macroscopic or gross hematuria.

	Hematuria	Hemoglobinuria
Definition	Presence of abnormal number of intact red cells in urine	Presence of free hemoglobin in urine
Urine color	Normal, smoky, red or brown	Pink, red or brown
Plasma color	Normal	Pink
Urine test on peroxidase activity	Positive	Positive
Urine microscopy	Many red cells	Occasional red cell
Serum haptoglobin	Normal	Low
Serum creatinine kinase	Normal	Normal
causes	Glomerulonephritis , lupus nephritis, Henoch schonlein purpura, calculi, tumors etc.	Intravascular hemolysis like Paroxysmal nocturnal hemoglobinuria, Paroxysmal cole hemogobinuria, incompatible blood transfusion.

a.Protect reagent strips from moisture and excessive heat to prevent loss of sensitivity
b.Brownish discoloration indicate significant loss of reactivity hence should not be used.
c.Store strips in a cool, dry area but not in refrigerator
d.Remove only enough reagent strips for immediate use and recap the bottle immediately
e.Avoid contamination of reagent strips
f.Do not touch the areas with fingers
g.Do not lay reagent strip on table surface- use clean sheet of paper
h.Do not use strips in the presence of volatile acids or alkaline fumes
i.Properly moisten reagent strips in a well mixed urine when testing the specimen
j.Avoid incomplete dipping, all test areas must be completely moistened
k.Avoid prolonged dipping, excessive dipping may cause bleaching of test reagents
l.Excessive care in reading strip. Observe time elements indicated in the directions for their use
m.Hold the reagent strip close to appropriate color chart when reading
n.Read only under good lighting condition.

Well mixed sample of urine (12 ml) is centrifuged in a centrifuge tube for 5 min at 1500rpm and supernatant is poured off. The tube is tapped at the bottom to re suspend the sediment (in 0.5mlof urine). A drop of this is placed on glass slide and covered with cover slip. Slide is examined under microscope using first low power and then high power objective. The condenser should be lowered to better visualize the elements by reducing the illumination.

Red cells- nil
White cells- 2-3/high power field
Epithelial cells- 5-6 per high power field.

Presence of >80% of dysmorphic cells signify glomerular pathology.

These are the only elements unique to kidneys which are found in urinary sediments. They are usually formed in distal convoluted tubules and collecting ducts. The major constituent of casts is Tamm- Horsfall proteins. The presence of urinary casts is also called as cylindruria. 

Casts are best seen un der low power objective (X10) with condenser lowered doen to reduce the illumination

Casts are colorless. Tamm horsfall proteins are better observed when condenser of the microscope is low.

Presence of casts indicates disease of renal tubules which secrete a mucoprotein ( Tamm Horsfall protein ) that gets solidified , forming a cast, subtype of cast whether granular, red cell or epithelial type suggests the pathology of renal parenchyma. Only hyaline casts may b found in healthy persons after exercise.

Sl no	Casts	Constituent and appearance	causes
1	Hyaline	Almost exclusively of Tamm-Horsfall proteins They appear colorless and of varied appeareance	Strenuous exercises Dehydration Stress Pathological as in all renal diseases
2	RBC	Suggests bleeding from nephron! They are more fragile, fragmented or irregular shape	glomerulonephritis
3	WBC	Suggests infection or inflammation in the nephron. They are composed of neutrophils and they appear granular and have irregular borders.	Pyelonephritis, acute interstitial nephritis
4	Epithelial	Difficult to differentiate from wbc , fragments of epithelium can be a clue.	Advanced tubular destruction
5	Fatty	Retractile and contain fat droplets or oval fat bodies.	Lipiduria due to nephritic syndrome, toxic tubular necrosis, crush injuries
6	Granular	Granular and of variable shapes. Originated from lysosomes of renal tubular epithelial cells	Strenuous exercise
7	waxy	Brittle and refractive, appear fragmented with jagged ends and can have notches in the sides	Extreme urine stasis and chronic renal failure
8	Broad	Broad/wider than normal	Same as above

Type of crystals suggest excessive excretion of that substance in urine, and if associated with the stone in the urinary tract, suggests the possible type of stone. Moreover, crystals of uric acid/urates are excreted in gout; triple phosphates in UTI due to urea splitting organism making the urine alkaline.

Crystalline triple phosphate (calcium ammonium magnesium phosphate) with prism shaped crystals and amorphous phosphates render pH alkaline. The latter get dissolved on addition of dilute acetic acid, thus differentiating these from albuminuria in the heat test for proteins.

Refers to urinary sediment consisting of red blood cells, white blood cells, oval fat bodies and all types of casts in roughly equal proportion
Causes: lupus nephritis, malignant hypertension, rapidly progressive glomerulonephritis and diabetic glomerulosclerosis.

Significant bacteriuria exists when there are
>105 bacterial colony forming units/ml of urine in a clean catch mid stream sample
>104 colony forming units /ml of urine in catheterized sample
>103 colony forming units /ml of urine in suprapubic aspiration sample.

a.Bacteria
b.Yeasts
c.Trichomonas vaginalis
d.Eggs of Schistoma hematobium
e.Microfilariae.