- Glucose is the sugar most commonly found in the urine, although other sugars, such as lactose, fructose , galactose, and pentose, may be found under certain condition.
- Usually less than 15 - 20 mg/dl (0.8 mmol) is excreted in the urine. But this amount cannot be detected by the routine laboratory tests. glycosuria: describe the presence of more than the normal amount of glucose in the urine.
- If the blood glucose concentration becomes too high (greater than 170 - 180 mg/dl), the excess glucose will not be reabsorbed into the blood and glucose start appearing in urine. The lowest blood glucose concentration that will result in glycosuria is termed as the renal threshold.
• Causes of Glycosuria :
1. Physiological :
a. After large ingestion of carbohydrates.
b. stimulates sympathetic nervous system such as excitement, stress.
c. 15 to 20% cases of pregnancy may be associated with physiological glycosuria.
d. Renal Glycosuria: glycosuria is found when blood glucose is in normal range, due to lowered renal threshold, Usually this is a benign condition.
2. Pathological Glycosuria :
a. Diabetes mellitus :
- The most common condition for glycosuria is diabetes mellitus, a metabolic disorder due to deficiencies of insulin. Glucose is not properly metabolized and blood glucose concentration rises, and when it is in range of 170 - 180 mg /dl , glucose starts appearing in urine.
b. Glycosuria due to other endocrine disorders :
- Deranged function of a number of endocrine disorders can cause hyperglycemia e.g :
1. Hyperthyroidism.
2. Hyperadrenalism.
3. Hyperpitutarism.
4. Some diseases of pancreas.
• Result physiologically
- Intravenous glucose or saline.
- Coffee, alcohol, tea, caffeine.
- Pharmacological agent, such as thiazides and other diuretics.
- Protein is a macromolecule, composed of one or more polypeptide chains, Albumin is one of the important proteins, which appears during a pathological condition. Globulins are excreted less frequently. Bence Jones protein is a specific type of globulin excreted in multiple myeloma, Proteinuria is the presence of protein in the urine.
• Causes of Proteinuria :
1. Increased permeability of the glomerulus :
- The glomerular membrane impermeable for protein molecules, when damaged these large protein molecules can pass through, and end up in the urine.
2. Decrease in normal reabsorption in the tubules :
- normally, the small amount of protein (with lower molecular weight), is reabsorbed back into the blood stream, Failure to reabsorb any protein from this large volume of glomerular filtrate will result in fairly large amounts of protein in the urine.
• Types of Proteinuria :
1. Accidental or false proteinuria :
- Occurs when there is a mixture of urine with a proteinous fluid such as pus, blood or vaginal discharge. These can occur in infection of the kidney, bladder or vagina.
2. Physiological or functional proteinuria :
- Is protein excretion in association with fever, exposure to heat or cold, excessive exercise, emotional stress, and later stage of pregnancy. Due to physiologic mechanism (renal vasoconstriction).
3. Postural (orthostatic) proteinuria :
- Is excretion of protein due to standing or sitting for a longtime. The proteinuria is intermittent and disappears when the individual lies down. It can also occur during abnormal curvature of spinal cord.
4. Renal or true proteinuria :
- Renal or true proteinuria occurs when protein passes from the blood into the urine because of some malfunction in the filtering system, either in the glomerulus or tubules.
• Tests for Urinary Protein :
- Precipitation or Turbidimetric Tests :
- general principle: protein is either precipitated out of the urine specimen by a chemical, usually a strong acid, or it is coagulated out with heat, tests include:
1. Robert's test.
2. Heller's test.
3. Sulphosalicylic Acid Test.
4. Heat and Acetic Acid Test.
- Also called Ketones, are a group of three related substances, acetone, acetoacetate (acetoacetic acid or diacetic acid), and β -hydroxybutyrate (β -hydroxybutyric acid). Ketone bodies are normal products of fat metabolism and normally not detectable in the blood or urine.
- When the rate of formation of ketone bodies is greater than the rate of their use, their levels begin to rise in the blood( ketonemia), and eventually in the urine( ketonuria).
• Causes :
1. starvation.
2. diabetes mellitus.
3. prolonged vomiting, severe diarrhea.
4. anesthesia.
5. severe liver damage.
6. high fat intake and low carbohydrate diet.
• physiological effect of ketone :
1. Acetoacetic acid and β hydroxybutyric acid contribute excess hydrogen ions to the blood, resulting in acidosis - a condition that tends to lower the blood pH. If not corrected in time this may result in death.
2. accumulation concerns the substance acetone and acetoacetic acid. Both have been found to be toxic to brain tissue when present in increased amounts in the blood. So this condition can result in permanent brain damage.
• Tests for Ketone Bodies :
1. Rothera's test.
2. Acetest tablet test.
3. Acetone powder test.
4. Reagent strip tests.
5. Lang's test.
- Bilirubin is a waste product that must be eliminated from the body. It is formed by the breakdown of hemoglobin in spleen and bone marrow .
- Tests for urinary bilirubin and urobilingen were normally performed only indicated by abnormal color of the urine or when liver disease or a hemolytic condition. It is an early sign of liver cell disease and obstruction of the bile flow from the liver (Obstructive or post - hepatic jaundice).
- Urine containing bilirubin :
- brown color and produce a yellow foam when shaken. Bilirubin is not stable in solution, but will be oxidized to biliverdin, which is a green pigment.
• Urine dipstick (strip):
Source: Simens Multistix 10 SG
