Lecture 10: Examining the urine

Question 1

When the urine is red what may be causing it to go this colour?

Answer 1

Blood

pathological or menstrual

Question 2

When the urine is purple what may be causing it to go this colour?

Answer 2

Infection

Question 3

When the urine is brown what may be causing it to go this colour?

Answer 3

Myoglobulin

Question 4

When the urine is bubbly what may be causing it to go this way?

Answer 4

Proteins present

Question 5

What is measured by the semiquantitative urinalysis

Answer 5

i. e. dipstick test
* Protein/Albumin
* Haem (‘blood’)
* pH
* Ketones
* Glucose
* Bilirubin
* Leucocyte
* Nitrites

Question 6

What does the term visible haematuria

Answer 6

blood can be seen with naked eye in the urine

Question 7

What does the term non-visible haematuria

Answer 7

dipstick haematuria but blood can only be seen with a microscope

Question 8

If blood is present, where can the blood be coming from?

Answer 8

Anywhere in the urinary tract

From the glomerulus in the kidneys downwards

Question 9

If proteins are present in the urine (proteinuria) implies there is a problem where?

Answer 9

Present of proteins implies that there is a problem with the glomerular.

Question 10

Explain how proteinuria is quantified

Answer 10

Ratio between protein:creatinine in the urine

Question 11

What biochemistry levels would indicate the kidneys are not working properly

Answer 11

Low eGFR - <60ml/min

Rise in serum creatinine within the eGFR>60mL/min range

Question 12

Define the term kidney injury/disease

Answer 12

Defined by reduced eGFR and detection and quantification of urine protein +/- blood

Question 13

What are the two main categories of kidney disease

Answer 13

Acute kidney injury (AKI)

Chronic kidney disease (CKD)

Question 14

What are the causes of kidney disease?

Answer 14

• Ineffective blood supply (reduced effective plasma volume or narrowed renal arteries)
• Glomerular diseases
• Tubulo-interstitial diseases
• Obstructive uropathy

Question 15

What does aldosterone do in the nephrons

Answer 15

• Acts on the nuclear mineralocorticoid receptors (MR) within the principal cells of the distal tubule and the collecting duct of the kidney nephron.
• It upregulates and activates the basolateral Na+/K+ pumps, which pumps three sodium ions out of the cell, into the interstitial fluid and two potassium ions into the cell from the interstitial fluid. This creates a concentration gradient which results in reabsorption of sodium (Na+) ions and water (which follows sodium) into the blood, and secreting potassium (K+) ions into the urine (lumen of collecting duct).

Question 16

Define oliguria

Answer 16

Low urine output

Oliguria is defined as a urine output that is less than 400 mL or 500 mL per 24h in adults - this equals 17 or 21 mL/hour.

Question 17

What can cause oliguria?

Answer 17

Dehydration. Dehydration is the most common cause of decreased urine output.

Infection or trauma.

Urinary tract obstruction. A urinary tract obstruction or blockage.

Medications e.g. NSAIDs

Question 18

How does dialysis work?

Answer 18

Blood is pumped into a machine.

The machine contains a semipermeable membrane with diaylsis fluid on the other side. The dialysis fluid is very salty.

Small solutes will moves down the concentration gradient into the dialysis solution e.g. potassium

The blood is pumped back into the patient with the unwanted material removed.

Question 19

Patients with chronic kidney disease are at risk of what?

Answer 19

• Patients with chronic kidney disease (CKD) are at risk of progressive deterioration in kidney function (and eventually the need for kidney replacement therapy).
• Patients with CKD are at risk of cardiovascular disease

Question 20

Describe chronic kidney disease

Answer 20

• Defined as the presence of kidney damage or decreased kidney function that persists for at least 3 months.
• CKD is often associated with progressive and irreversible loss of large numbers of functioning nephrons.
• Serious clinical symptoms usually do not occur until the number of functional nephrons falls to at least 70 to 75 percent below normal.

Question 21

Describe the pathogenesis of chronic kidney disease

Answer 21

An initial insult to the kidney leads to progressive deterioration of kidney function and further loss of nephrons

A slowly progressing vicious cycle that eventually terminates in end stage renal disease