Urine as an Indicator of Disease

Question 1

List 2 advantages of urinalysis.

Answer 1

1 - It is a non-invasive procedure.

2 - It is easily obtained.

Question 2

List the contents of normal urine in order from highest mass present to lowest.

Answer 2

1 - Water.

2 - Urea.

3 - Cl-.

4 - Na+.

5 - K+.

6 - Creatinine.

7 - Bicarbonate.

8 - Uric acid.

Question 3

What is the average volume of urine produced per day?

Answer 3

1.4L

Question 4

List 4 factors that influence the volume of urine produced.

Answer 4

1 - Body size.

2 - Diet.

3 - Fluid intake.

4 - Health.

Question 5

Define pseudohaematuria.

Answer 5

Red-coloured urine in the absence of blood.

Question 6

List 4 causes of pseudohaematuria.

Answer 6

1 - Free Hb.

2 - Myoglobin.

3 - Porphyrins.

4 - Drugs.

Question 7

What might be present in the urine to produce a red/brown colour?

Answer 7

Conjugated bilirubin.

Question 8

What might be present in the urine to produce a black colour?

Answer 8

Melanin due to a disseminated melanoma.

Question 9

How is a microscopic examination of a urine sample done?

Answer 9

1 - Centrifuge the sample.

2 - Examine sediment for bacteria, cells or urinary casts.

Question 10

What are urinary casts?

Answer 10

Microscopic cylindrical structures composed of the Tamm-Horsfall mucoprotein, which is secreted by renal tubules.

Question 11

When might urinary casts be present in the urine in the absence of disease?

Answer 11

Post-exercise.

Question 12

How is the presence of bacteria seen in a microscopic examination confirmed?

Answer 12

By using a dipstick to test for nitrite production, then producing a culture.

Question 13

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.

Answer 13

1 - White cells might indicate a kidney infection.

2 - Red cells might indicate damage to the urinary tract.

Question 14

List 4 examples of crystals that might be present in the urine.

Answer 14

1 - Oxalate crystals.

2 - Triple phosphate crystals.

3 - Cystine crystals.

4 - Amorphous crystals.

Question 15

List 3 diseases / conditions that cause acidic pH extremes.

Answer 15

1 - Uncontrolled diabetes.

2 - Starvation.

3 - Respiratory acidosis.

Question 16

List 2 molecules that might be found in the urine due to acidic pH extremes.

Answer 16

1 - Cystine crystals.

2 - Excess uric acid.

Question 17

List 2 diseases / conditions that cause alkaline pH extremes.

Answer 17

1 - Urinary tract obstructions.

2 - Respiratory alkalosis.

Question 18

List 3 molecules that might be found in the urine due to alkaline pH extremes.

Answer 18

1 - Ca2+.

2 - CaCO3.

3 - MgPO4.

Question 19

What is the normal pH range for urine?

Answer 19

4.5-8

Question 20

Give an example of a food that causes acidic urine.

Answer 20

Meat.

Question 21

List 2 foods that cause alkaline urine.

Answer 21

1 - Citrus fruits.

2 - Vegetables.

Question 22

What is the function of creatine phosphate?

Answer 22

It is an energy reserve in muscles.

Question 23

What might cause an increase in urine creatinine concentration?

Answer 23

Excessive meat intake.

Question 24

List 3 factors that might cause a decrease in urine creatinine concentration.

Answer 24

1 - Wasting diseases.

2 - Malnutrition.

3 - Poor renal blood flow / function.

Question 25

List 2 pre-renal causes of an increase in solute excretion in the urine.

Answer 25

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.

Question 26

List 2 pre-renal causes of a decrease in solute excretion in the urine.

Answer 26

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.

Question 27

Give an example of a renal cause of an increase in solute excretion in the urine.

Answer 27

Glomerular malfunction due to infection, autoimmune disease or inflammation, causing leakage.

Question 28

List 6 causes of tubular malfunction.

Answer 28

1 - Infection. 2 - Autoimmune disease. 3 - Inflammation. 4 - Necrosis. 5 - Drugs. 6 - Toxins.

Question 29

What is the purpose of urea?

Answer 29

It is the non-toxic end product of nitrogen metabolism.

Question 30

List 7 factors that increase the concentration of urea in the urine.

Answer 30

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.

Question 31

List 6 factors that decrease the concentration of urea in the urine.

Answer 31

1 - Low protein diet. 2 - Severe liver disease. 3 - Glomerulonephritis. 4 - Acute tubular necrosis. 5 - Poor renal blood supply. 6 - Renal obstruction.

Question 32

What is the outcome of decreased urea excretion? List 3 symptoms that might result from this outcome. What causes these symptoms?

Answer 32

- Hyperammonaemia. 1 - Lethargy. 2 - Irritability. 3 - Coma. - These symptoms are caused by excess ammonia crossing the blood brain barrier.

Question 33

What proportion of filtered glucose is normally found in the urine?

Answer 33

<0.1%.

Question 34

Give an example of a test for urine glucose.

Answer 34

A reagent strip containing glucose oxidase.

Question 35

List 3 causes of metabolic hyperglycaemia.

Answer 35

1 - Type 1 diabetes. 2 - Anxiety / stress. 3 - Phaeochromocytoma (adrenal tumour).

Question 36

List 3 conditions that reduce the renal threshold for glucose excretion (results in glucose excretion in the urine despite regular blood glucose concentration).

Answer 36

1 - Pregnancy. 2 - Renal glycosuria (a genetic condition). 3 - Tubular malfunction.

Question 37

What is fanconi syndrome?

Answer 37

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.

Question 38

List 2 causes of high ketone concentration in the urine.

Answer 38

1 - Uncontrolled type 1 diabetes. 2 - Starvation.

Question 39

List 3 causes of aminoaciduria.

Answer 39

1 - Generalised tubular damage. 2 - Specific transporter defects. 3 - Raised plasma amino acids.

Question 40

List 2 specific examples of aminoacidurias that are caused by transporter defects.

Answer 40

1 - Cystinuria. 2 - Hartnup's disease.

Question 41

List 2 specific examples of aminoacidurias that are caused by raised plasma amino acids.

Answer 41

1 - Phenylketonuria. 2 - Cystinosis.

Question 42

List 2 causes of high urine concentration of conjugated bilirubin.

Answer 42

1 - Liver damage. 2 - Obstructed bile ducts.

Question 43

What is a phaeochromocytoma?

Answer 43

An adrenal medullary tumour causing excessive secretion of adrenaline.

Question 44

List 4 symptoms of excess adrenaline secretion (due to phaeochromocytomas).

Answer 44

1 - High plasma free fatty acids. 2 - Hyperglycaemia. 3 - Tachycardia. 4 - Hypertension.

Question 45

What is excreted in excess in a person with phenylketonuria?

Answer 45

Phenylpyruvate.

Question 46

Which enzyme is deficient in people with phenylketonuria? What is the function of this enzyme?

Answer 46

- Phenylalanine hydroxylase. | - It converts phenylalanine into tyrosine.

Question 47

List 3 symptoms of phenylketonuria.

Answer 47

1 - Irritability. 2 - Fits. 3 - Mental retardation.

Question 48

Describe the pathophysiology of phenylketonuria.

Answer 48

- 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.

Question 49

Give an example of a treatment of phenylketonuria.

Answer 49

Dietary management.

Question 50

What is the cutoff molecular mass for glomerular filtration?

Answer 50

70kDa.

Question 51

What is the normal rate of excretion for proteins in the urine?

Answer 51

200mg / 24 hours.

Question 52

Give an example of a condition which might cause proteinuria. Briefly describe the pathophysiology of this disease.

Answer 52

- Nephrotic syndrome. | - Damage to the capillary tuft.

Question 53

What is orthostatic proteinuria?

Answer 53

Proteinuria that only occurs when standing.

Question 54

Give an example of an indicator of poor tubular function.

Answer 54

Presence of beta-2 microglobulin in the urine.

Question 55

How can you distinguish between prerenal and renal causes of proteinuria?

Answer 55

- 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.