Renal Function

Question 1

Describe the gross anatomy of the kidneys

Answer 1

• 2 retroperitoneal organs
• receive 25% of cardiac output
• right is slightly lower than the liver

Question 2

Main functions of the kidneys

Answer 2

• excretion of waste
• maintain EFC volume & composition
• endocrine function

Question 3

Briefly describe urine formation

Answer 3

• glomerulus forms filtrate and tubules process the filtrate to form urine

Question 4

Describe kidney disease

Answer 4

• heterogenous disorder
• usually destruction of complete nephrons
• acute kidney injury

Question 5

How do we assess a patient with kidney disease ?

Answer 5

• through clinical examination
• laboratory investigations
• urinalysis
• GFR
• urea & electrolytes

Question 6

Signs & symptoms of renal failure

Answer 6

• symptoms of Uraemia
• disorders of Micturition
• disorders of urine volume
• alterations in urine composition
• pain
• oedema

Question 7

Define symptoms of Uraemia

Answer 7

nausea , vomiting , lethargy

Question 8

Define disorders of micturition

Answer 8

• frequency
• nocturia
• retention

Question 9

What are some biochemical tests for renal function?

Answer 9

• Urinalysis = appearance, pH, glucose, protein, sediment
• proteinuria
• measurement of GFR = clearance tests, plasma creatinine

Question 10

Describe GFR

Answer 10

• Glomerular Filtration Rate
• essential to normal function
• quantity of filtrate formed each minute

Question 11

How do you work out clearance ?

Answer 11

Clearance = (U x V) /P

Question 12

What does U stand for in clearance equation?

Answer 12

U = urinary conc. of substance

Question 13

What does V stand for in the clearance equation?

Answer 13

V = rate of urine formation (mL/min)

Question 14

What does P stand for in the clearance equation ?

Answer 14

P = plasma conc. of a substance

Question 15

What is normal for GFR?

Answer 15

100ml/min

Question 16

What are some direct measurements of GFR?

Answer 16

• insulin clearance
• EDTA clearance
• creatinine clearance

Question 17

What are some estimated assessments of GFR?

Answer 17

• Cockroft & Gault
• MDRD formula
• CKD-EPI

Question 18

Describe Creatinine Clearance

Answer 18

• fairly straightforward
• times urine collection for creatinine measurement
• blood sample taken within measurement period

Question 19

What are some problems with creatinine clearance?

Answer 19

• practical problems of accurate urine collection and volume measurement
• interference in creatinine measurement

Question 20

Describe Serum Creatinine Concentration

Answer 20

• simple test to assess glomerular function
• useful in monitoring changes in CKD

Question 21

What are some limitations of Serum Creatinine Conc?

Answer 21

• conc. depends on balance between input & output
• production determined by muscle mass - related to age,sex,weight
• reference limits can be misleading

Question 22

Describe Cockroft & Gault

Answer 22

• uses serum creatinine & weight to predict creatine clearance
• unreliable if patients is obese

Question 23

What are advantages of eGFR ?

Answer 23

• doesn’t require any infusion
• easy to measure
• lab computer automatically
• doesn’t require urine collection