Urine as an Indicator of Disease Flashcards
List 2 advantages of urinalysis.
1 - It is a non-invasive procedure.
2 - It is easily obtained.
List the contents of normal urine in order from highest mass present to lowest.
1 - Water.
2 - Urea.
3 - Cl-.
4 - Na+.
5 - K+.
6 - Creatinine.
7 - Bicarbonate.
8 - Uric acid.
What is the average volume of urine produced per day?
1.4L
List 4 factors that influence the volume of urine produced.
1 - Body size.
2 - Diet.
3 - Fluid intake.
4 - Health.
Define pseudohaematuria.
Red-coloured urine in the absence of blood.
List 4 causes of pseudohaematuria.
1 - Free Hb.
2 - Myoglobin.
3 - Porphyrins.
4 - Drugs.
What might be present in the urine to produce a red/brown colour?
Conjugated bilirubin.
What might be present in the urine to produce a black colour?
Melanin due to a disseminated melanoma.
How is a microscopic examination of a urine sample done?
1 - Centrifuge the sample.
2 - Examine sediment for bacteria, cells or urinary casts.
What are urinary casts?
Microscopic cylindrical structures composed of the Tamm-Horsfall mucoprotein, which is secreted by renal tubules.
When might urinary casts be present in the urine in the absence of disease?
Post-exercise.
How is the presence of bacteria seen in a microscopic examination confirmed?
By using a dipstick to test for nitrite production, then producing a culture.
List 2 cells that might be found in the urine that are indicative of disease.
For each cell, state the disease that they might indicate.
1 - White cells might indicate a kidney infection.
2 - Red cells might indicate damage to the urinary tract.
List 4 examples of crystals that might be present in the urine.
1 - Oxalate crystals.
2 - Triple phosphate crystals.
3 - Cystine crystals.
4 - Amorphous crystals.
List 3 diseases / conditions that cause acidic pH extremes.
1 - Uncontrolled diabetes.
2 - Starvation.
3 - Respiratory acidosis.
List 2 molecules that might be found in the urine due to acidic pH extremes.
1 - Cystine crystals.
2 - Excess uric acid.
List 2 diseases / conditions that cause alkaline pH extremes.
1 - Urinary tract obstructions.
2 - Respiratory alkalosis.
List 3 molecules that might be found in the urine due to alkaline pH extremes.
1 - Ca2+.
2 - CaCO3.
3 - MgPO4.
What is the normal pH range for urine?
4.5-8
Give an example of a food that causes acidic urine.
Meat.
List 2 foods that cause alkaline urine.
1 - Citrus fruits.
2 - Vegetables.
What is the function of creatine phosphate?
It is an energy reserve in muscles.
What might cause an increase in urine creatinine concentration?
Excessive meat intake.
List 3 factors that might cause a decrease in urine creatinine concentration.
1 - Wasting diseases.
2 - Malnutrition.
3 - Poor renal blood flow / function.
List 2 pre-renal causes of an increase in solute excretion in the urine.
1 - An increase in solute production elsewhere in the body (including increased intake).
2 - The solute is abnormal, so there is no suitable transporter preventing filtration.
List 2 pre-renal causes of a decrease in solute excretion in the urine.
1 - A decrease in solute production elsewhere in the body (including decreased intake).
2 - A decrease in delivery due to cardiac failure, haemorrhage or burns.
Give an example of a renal cause of an increase in solute excretion in the urine.
Glomerular malfunction due to infection, autoimmune disease or inflammation, causing leakage.
List 6 causes of tubular malfunction.
1 - Infection.
2 - Autoimmune disease.
3 - Inflammation.
4 - Necrosis.
5 - Drugs.
6 - Toxins.
What is the purpose of urea?
It is the non-toxic end product of nitrogen metabolism.
List 7 factors that increase the concentration of urea in the urine.
1 - Excess protein intake.
Factors that trigger greater protein catabolism:
2 - Protein energy malnutrition.
3 - Uncontrolled type 1 diabetes.
4 - Infections.
5 - Burns.
6 - Wasting diseases.
7 - Trauma.
List 6 factors that decrease the concentration of urea in the urine.
1 - Low protein diet.
2 - Severe liver disease.
3 - Glomerulonephritis.
4 - Acute tubular necrosis.
5 - Poor renal blood supply.
6 - Renal obstruction.
What is the outcome of decreased urea excretion?
List 3 symptoms that might result from this outcome.
What causes these symptoms?
- Hyperammonaemia.
1 - Lethargy.
2 - Irritability.
3 - Coma.
- These symptoms are caused by excess ammonia crossing the blood brain barrier.
What proportion of filtered glucose is normally found in the urine?
<0.1%.
Give an example of a test for urine glucose.
A reagent strip containing glucose oxidase.
List 3 causes of metabolic hyperglycaemia.
1 - Type 1 diabetes.
2 - Anxiety / stress.
3 - Phaeochromocytoma (adrenal tumour).
List 3 conditions that reduce the renal threshold for glucose excretion (results in glucose excretion in the urine despite regular blood glucose concentration).
1 - Pregnancy.
2 - Renal glycosuria (a genetic condition).
3 - Tubular malfunction.
What is fanconi syndrome?
A disorder of kidney tubule function that results in excess excretion of:
1 - Glucose.
2 - Bicarbonate.
3 - Phosphates.
4 - Uric acid.
5 - Potassium.
6 - Amino acids.
List 2 causes of high ketone concentration in the urine.
1 - Uncontrolled type 1 diabetes.
2 - Starvation.
List 3 causes of aminoaciduria.
1 - Generalised tubular damage.
2 - Specific transporter defects.
3 - Raised plasma amino acids.
List 2 specific examples of aminoacidurias that are caused by transporter defects.
1 - Cystinuria.
2 - Hartnup’s disease.
List 2 specific examples of aminoacidurias that are caused by raised plasma amino acids.
1 - Phenylketonuria.
2 - Cystinosis.
List 2 causes of high urine concentration of conjugated bilirubin.
1 - Liver damage.
2 - Obstructed bile ducts.
What is a phaeochromocytoma?
An adrenal medullary tumour causing excessive secretion of adrenaline.
List 4 symptoms of excess adrenaline secretion (due to phaeochromocytomas).
1 - High plasma free fatty acids.
2 - Hyperglycaemia.
3 - Tachycardia.
4 - Hypertension.
What is excreted in excess in a person with phenylketonuria?
Phenylpyruvate.
Which enzyme is deficient in people with phenylketonuria?
What is the function of this enzyme?
- Phenylalanine hydroxylase.
- It converts phenylalanine into tyrosine.
List 3 symptoms of phenylketonuria.
1 - Irritability.
2 - Fits.
3 - Mental retardation.
Describe the pathophysiology of phenylketonuria.
- A deficiency in phenylalanine hydroxylase causes accumulation of phenylalanine and transamination byproducts such as phenylalanine pyruvate and phenylalanine acetate which can overspill into the urine.
- Phenylalanine adversely affects the brain.
Give an example of a treatment of phenylketonuria.
Dietary management.
What is the cutoff molecular mass for glomerular filtration?
70kDa.
What is the normal rate of excretion for proteins in the urine?
200mg / 24 hours.
Give an example of a condition which might cause proteinuria.
Briefly describe the pathophysiology of this disease.
- Nephrotic syndrome.
- Damage to the capillary tuft.
What is orthostatic proteinuria?
Proteinuria that only occurs when standing.
Give an example of an indicator of poor tubular function.
Presence of beta-2 microglobulin in the urine.
How can you distinguish between prerenal and renal causes of proteinuria?
- If the protein has a low Mr (e.g. myoglobin), the problem is likely prerenal.
- If the protein has a high Mr (e.g. albumin), the problem is likely renal.
