Kidney Disease and Renal Failure

Question 1

Define “pre-renal acute kidney injury”

Answer 1

Sudden reduction in blood flow to the kidneys, causing a loss of kidney function . Nothing is wrong with the kidney itself

Question 2

Define “post-renal acute kidney injury”

Answer 2

acute kidney injury caused by disease states downstream of the kidney and most often occurs as a consequence of urinary tract obstruction

Question 3

What is the functional unit of the kidney?

Answer 3

Nephron

Question 4

State the route which a filtrate takes as it passes through a nephron

Answer 4

Afferent arteriole
Glomerulus
Bowman's capsule
Efferent arteriole
Proximal convoluted tubule
Descending loop of Henle
Ascending loop of Henle
Distal convoluted tubule
Collecting duct

Question 5

How can we express mathematically the three renal processes which comprise urine formation?

Answer 5

Urine excretion rate = Filtration rate - Reabsorption rate + Secretion rate

Question 6

How does the Glomerular capillary membrane differ to other capillary membranes?

Answer 6

Normal capillary membranes have two layers: Fenestrated endothelium and basement membrane.

Glomerular capillary membranes have an additional layer of epithelial cells (podocytes), surrounding the outer surface

Question 7

In the glomerular capillary membrane, there are large fenestrations in the endothelium. Why are large plasma proteins still not passed through?

Answer 7

The endothelial cells have fixed negative charges which prevent this

Question 8

Discuss the structure of the podocytes

Answer 8

Podocytes encircle the outer surface of capillaries. They are seperated by gaps called slit junctions. They also have negative charges which provide additional restriction to filtration

Question 9

What are the four characteristics of Nephrotic syndrome?

Answer 9

Peripheral oedema
Proteinuria
Hypoalbuminaemia
Hypercholesterolaemia

Question 10

How is Nephrotic syndrome biochemically defined?

Answer 10

Proteinuria / Hypoalbuminaemia < 30g/L

Question 11

What is the Macula Densa, and briefly what is its role?

Answer 11

It is a specialisation of the Distal Convoluted Tubule, and monitors level of NaCl in fluid of DCT

Question 12

Outline the role of the Macula Densa if NaCl levels are low in the fluid

Answer 12

1. Macula Densa releases renin from Juxtoglomerular cells, which cause an increase in angiotensin II and aldosterone
2. Angiotensin II acts on the PCT
3. Aldosterone acts on the collecting duct
4. This stimulates NaCl and water reabsorption

Question 13

What maintains capillary oncotic pressure?

Answer 13

Albumin

Question 14

Define oncotic pressure

Answer 14

A pressure exerted by proteins i.e. albumin in a blood vessel’s plasma that tends to pull water into circulation

Question 15

What are three main PRIMARY causes which can lead to Nephrotic syndrome?

(Tends to occur in children)

Answer 15

1. Minimal change disease (MCD)
2. Focal segmental glomerulosclerosis (FSGS)
3. Membranous nephropathy (MN)

Question 16

State some SECONDARY causes of Nephrotic syndrome?

Tends to occur in adults

Answer 16

1. Diabetic nephropathy
2. Systemic Lupus Erythematous
3. Amyloidosis
4. Cancer
5. Chronic viral infection

Question 17

State the four characteristics of Nephritic Syndrome

Answer 17

1. Proteinuria
2. Haematuria
3. Oligouria
4. Hypertension

Question 18

State some conditions associated with Nephritic syndrome

Answer 18

Post-streptococcal glomerulonephritis
IgA nephropathy
Goodpasture’s syndrome

Question 19

Outline how SLE can cause disease of the glomerulus

Answer 19

Autoantibodies form or are deposited in the glomeruli, causing complement activation, leading to inflammation

Question 20

Outline how Goodpasture’s Syndrome can cause disease of the glomerulus

Answer 20

In situ autoantibodies in kidneys, causing inflammation

Question 21

Outline how IgA nephropathy can cause disease of the glomerulus

Answer 21

IgA form deposits in the glomerulus, causing inflammation

Question 22

Outline how Alport syndrome can cause disease of the glomerulus

Answer 22

Mutations in the collagen biosynthetic pathway, leading to dysfunctional collagen network production in the glomerulus and improper filtration

Question 23

Outline how Post-streptococcal glomerulonephritis can cause disease of the glomerulus

Answer 23

Strep bacteria does not attack kidneys directly, but an infection may stimulate the immune system to produce antibodies which deposit in the glomeruli

Question 24

Outline how diabetic nephropathy can cause disease of the glomerulus

Answer 24

Elevated glucose levels appear to increase speed of blood flow into kidney, putting a strain of glomerular filtration and raising blood pressure

Question 25

Outline how Membraneous Nephropathy can cause disease of the glomerulus

Answer 25

Unusual deposits of IgG and complement C3 in the glomerulus

Question 26

Chronic Kidney Disease can be divided into how many stages? What is the first and last stage?

Answer 26

Stage 1: Normal GFR
Stage 2
Stage 3
Stage 4
Stage 5: < 15ml/min or RRT