Y Lecture 9&10: Acute and Chronic renal failure 1 & 2

Question 1

What is a normal GFR?

Answer 1

120mls/ min

Question 2

What are the roles of the proximal and distal convoluted tubules?

Answer 2

Proximal: bulk resorption of glomerular filtrate

Distal: fine tuning of composition of filtrate

Question 3

What is the gold-standard measure of GFR?

Answer 3

Inulin clearance

Question 4

What is the most clinically-viable measure of GFR?

Answer 4

51Cr-EDTA and 99Tc-DTPA

Question 5

How can plasma creatinine be used to estimate GFR?

Answer 5

Clearance = P(U x V) P = plasma concentrationU = urinary concentrationV = plasma volume

Question 6

What would invalidate a creatinine-based measurement of GFR?

Answer 6

If function is not in a steady state

Question 7

Why does plasma urea have a limited clinical value for measuring renal function?

Answer 7

Because it can be affected by many things so is highly variable

Question 8

Describe the movement of creatinine from blood to urine

Answer 8

Freely filteredActively transported into urine by tubular cells

Question 9

What equation can be used to refine your interpretation of creatinine clearance?

Answer 9

Cockcroft Gault Equation

Question 10

What is the equation for estimated creatinine clearance?

Answer 10

((1.23 x (140- age) x weight))/ serum creatinineAdjust by 0.85 if female

Question 11

What is cystatin C, and why is it particularly useful?

Answer 11

Alternative to creatinine clearance Largely unaffected by muscle mass/ gender/ age

Question 12

In what condition does cystatin C not give a reliable result for GFR estimation?

Answer 12

Hypo/ hyperthyroidism

Question 13

How can proteinuria be quantified?

Answer 13

Spot urine measurement

Question 14

What can a 24-hour urine collection be used for?

Answer 14

1. Creatinine clearance estimation2. Examination for stone-forming elements3. Proteinuria quantification (but this can also be done on spot urine testing) 4. Electrolyte estimation (but this can also be done on spot urine testing)

Question 15

What is the first choice of imaging in a suspected renal stone?

Answer 15

Abdo X ray

Question 16

What is the first choice of imaging to assess renal blood flow?

Answer 16

USS with doppler

Question 17

What is the first choice of imaging in investigating renal structural abnormalities?

Answer 17

CT

Question 18

What options are available for functional imaging of the kidney?

Answer 18

Static and dynamic renograms

Question 19

Recall the increases in creatinine that define each stage of AKI

Answer 19

Stage 1: 1.5-1.9 x the referenceStage 2: 2-2.9 x the referenceStage 3: >=3 x the reference (or >354)

Question 20

Systematically recall some differentials for pre-renal AKI

Answer 20

Water loss: diuresis/ vomiting
Selective ischaemia: renal artery stenosis
Blood loss: road traffic accident/ drugs affecting renal blood flow
Oedematous states: heart failure

Question 21

Recall 5 drug classes that can predispose to pre-renal AKI and the mechanism of each of these

Answer 21

NSAIDs - decrease afferent arteriolar dilatationCalcineurin inhibitors - decrease afferent arteriolar dilatationACE inhibitors: decrease efferent constrictionARBs: decrease efferent constriction Diuretics: affect tubular function and pre-load

Question 22

When does AKI become only partially reversible?

Answer 22

When acute tubulr necrosis occurs

Question 23

Recall 3 differentials for the causes of post-renal AKI

Answer 23

It’s an obstructive pathology: 1. Stone in renal pelvis2. Bilateral ureteric obstruction (BPH) 3. Blocked urinary catheter

Question 24

Systematically recall some causes of intrinsic renal AKI

Answer 24

Vascular causes (vasculitis/ vasculitides) Glomerular (glomerulonephritis) Tubular (ATN) Interstitial (analgesic nephropathy) Big proteins that clog up nephron - myoglobin (rhabdomyolysis), immunoglobin (amyloidosis, myeloma) Toxins (contrast/ drugs)

Question 25

What is the most common cause of intrinsic renal AKI?

Answer 25

Acute tubular necrosis

Question 26

What are the 2 best measures of AKI severity?

Answer 26

CreatinineUrine output

Question 27

How is CKD stage 1 defined?

Answer 27

Kidney damage with normal GFR (>90)

Question 28

How is CKD stage 5 defined?

Answer 28

End-stage - GFR <15

Question 29

What is the best measure of prognosis in CKD?

Answer 29

Albumin creatinine ratio

Question 30

What is the most common cause of CKD?

Answer 30

Diabetes by a long mile

Question 31

How can CKD cause a failure of homeostatsis?

Answer 31

1. Can cause acidosis due to reduced H+ excretion2. Can cause hyperkalaemia due to reduced K+ excretion

Question 32

How can CKD cause a failure of hormonal function?

Answer 32

1. Can lead to a normochromic normacytic anaemia due to failure of EPO production2. Can cause renal bone disease due to failure of PTH action

Question 33

How can end-stage CKD affect the heart?

Answer 33

CKD –> less PTH action –> calcium elevated –> cardiac myocyte dysfunction –> uraemic cardiomyopathy

Question 34

How should renal bone disease be treated (3 ways)?

Answer 34

1. Phosphate control (phosphate binding drugs) 2. Vitamin D receptor activators (eg 1 alpha calcidol) 3. PTH suppression (cinacalcet)