Chronic kidney disease

Question 1

What is the definition of chronic kidney disease?

Answer 1

Kidney damage or eGFR<60ml/min per 1.73m^2 for 3 months or more

Question 2

Describe creatinine clearance

Answer 2

• Serum creatinine is a product of muscle metabolism
• Production and serum levels are fairly constant
• 24hr creatinine clearance is often inaccurate
• It is freely filtered but there is tubular secretion

Question 3

What are the problems with using serum creatinine to calculate GFR?

Answer 3

1. Exponential relationship lead to a slow recognition of the loss of the first 70% of renal function i.e. lag time and surprise at the sudden rise of creatinine with a late renal referral
2. Effect of muscle mass leads to the overestimation of function in low muscle groups e.g. amputees, RA, elderly

Question 4

What are the problems with eGFR?

Answer 4

• Only validated in whites and African Americans
• Mean age 50 so is not validated in the elderly
• Values above 60ml/min are not distinguishable so reported as eGFR>59ml/min
• Drug dosing - doesn’t take weight into account
• Not valid in AKI as creatinine must be steady state
• Not validated in pregnancy

Question 5

Explain the NKF classification

Answer 5

2 measurements taken over 1 month apart
•Stage 1: GFR>90: Normal or increased eGFR with other evidence of kidney damage
•Stage 2: GFR 60-89: Slight decrease in eGFR with other evidence of kidney damage
•Stage 3a: eGFR 45-59: moderate decrease in eGFR
•Stage 3b: eGFR 30-44: moderate decrease in eGFR
•Stage 4: eGFR 15-29: severe decrease in eGFR
•Stage 5: Established renal failure

Question 6

What can cause a 1+ protein result on a dipstick?

Answer 6

• Fever
• exercise
• normal

Question 7

What can we use to quantify proteinuria?

Answer 7

• 24 hour urine collection
• PCR
• ACR

Question 8

What is a normal ACR?

Answer 8

<2.5

Question 9

What is a normal PCR?

Answer 9

<20

Question 10

What is a normal albuminuria:ACR?

Answer 10

> 30

Question 11

What is the nephrotic range proteinuria?

Answer 11

PCR>300

Question 12

Describe the appearance of diabetic nephropathy on histology

Answer 12

Kimmelstien-Wilson nodules

Question 13

What is the aetiology of reflux nephropathy/chronic pyelonephritis?

Answer 13

• Valve between the bladder and ureter remains open
• Urine refluxes up the ureter
• Kidney becomes scarred, inflammation response

Question 14

What are the symptoms of advanced chronic kidney disease?

Answer 14

• Pruritus
• Nausea, anorexia, weight loss
• Fatigue
• Leg swelling (due to salt and fluid clearance)
• Breathlessness
• Nocturia
• Joint/bone pain
• Confusion

Question 15

What are the signs of advanced CKD?

Answer 15

• Peripheral and pulmonary oedema
• Pericardial rub and pericarditis
• Rash/excoriation
• Hypertension
• Tachypnoea
• Cachexia
• Pallor and/or lemon yellow tinge

Question 16

What are the general principles for the mangement of CKD?

Answer 16

• Targeted screening for CKD
• Interventions to slow the rate of progression of CKD and reduce cardiovascular risk
• Medicines to replace impaired individual functions of the kidney
• Advanced planning for future renal replacement therapy (RRT)
• Renal replacement therapy

Question 17

How do you slow the progression of chronic kidney disease?

Answer 17

• Aggressive BP control
• Good diabetic control
• Smoking cessation
• Diet
• Lowering cholesterol
• Treat acidosis

Question 18

Which drugs should you use for hypertension in CKD?

Answer 18

• ACEi/ARBs but caution if bilateral renal artery stenosis

* All BP lowering drugs will reduce the rate of progression

Question 19

Explain anaemia in CKD and its management

Answer 19

• Common, especially when eGFR<30
• Iron absorption and utilisation suboptimal
• Replace iron, B12 and folate first if low
• ESA e.g. darbepoietin alfa every 2 weeks
• Target Hb 100-120g/l

Question 20

Describe the pathophysiology of secondary hyperparathyroidism

Answer 20

• Chronic kidney disease results in increased phosphorus due to reduced clearance and decreased vitamin D
• This causes a reduction in calcium resulting in the thyroid increasing production of PTH

Question 21

What is the treatment of CKD-MBD?

Answer 21

• Activated vitamin D
• Occasionally Mg supplements
• Phosphate binders : calcium based and non calcium based
• Calcimimetic
• Partathyroidectomy

Question 22

What are the phosphate binders?

Answer 22

• Calcium based: calcium carbonate/acetate

* Non-calcium: sevelamer, lanthanum, aluminium

Question 23

What are the types of RRT?

Answer 23

• Conservative care
• Transplant
• Hospital based therpaies
• Home based therapies

Question 24

When should you start dialysis?

Answer 24

• Individual approach based on symptoms
• Most start with eGFR 6-8ml /min
• Weight loss, persistent nausea, persistent hyperkalaemia, acidosis, severe hyperphosphataemia or pruritis
• Problematic fluid overload
• Best to have permanent access