Chronic Kidney Disease

Question 1

what are the functions of the kidney?

Answer 1

Question 2

Measurement of kidney function and definition of chronic kidney disease

Question 3

How do we assess for kidney disease?

Answer 3

• Filtration (excretory) function - remove
• Filtration (barrier) function - retain
• Anatomy - abnormality

Question 4

what is glomerular filtration rate?

Answer 4

estimates how much blood passes through the glomeruli each minute

One method of determining GFR from creatinine is to collect urine (usually for 24 h) to determine the amount of creatinine that was removed from the blood over a given time interval

Pressure difference leads to glomerular filtration

Normal GFR = 120/min

Question 5

How do you measure excretory Renal Function?

Answer 5

• Inulin clearance
• Isotope GFR
• 24 hour urine collection plus blood test
• GFR estimating equations

Creatinine will not be raised above the normal range until 60% of total kidney function is lost

Serum creatinine is the basic thing used to measure kidney function

Need to lose around 50% or more of GFR before you see a rise in your creatinine

There are pitfalls to using it

African Americans will have a higher serum creatinine level at any level of creatinine clearance because they have a higher muscle mass

Question 6

What is the problem of the relationship between serum creatinine and GFR?

Answer 6

Creatinine is generated from breakdown of muscle

Not everyone has the same muscle mass

Question 7

What does the relationship between serum creatinine and GFR depend on?

Answer 7

Age

Ethnicity

Gender

Weight

Other issues eg liver disease

Question 8

What are some formulae that may be used to estimate GFR from serum creatinine?

Answer 8

• Cockcroft Gault = ([140-age] x weight x 1.23) / SCr x (0.85 if female)
• MDRD 4 variable equation = 175 x [SCr/88.4] -1.154 x [age] -0.203 x (0.742 if female) x (1.212 if black)
• CKD-EPI equation

Question 9

How do we assess kidney excretory function?

Answer 9

International CKD Classification System

Question 10

What things do we test for kidney disease?

Answer 10

• Filtration (excrete out) function – use estimates of GFR (eGFR) from creatinine blood test
• Filtration (keep in) function
• Anatomy

Question 11

what things can cross the glomerular basement membrane (GBM)?

Answer 11

–Water

–Electrolytes

–Urea

–Creatinine

Question 12

what things cross the GBM but are reabsorbed in the proximal tubule?

Answer 12

–Glucose

–Low molecular weight proteins (α2 microglobulin)

Question 13

what things do not cross the GBM?

Answer 13

–Cells (RBC, WBC)

–High molecular weight proteins (albumin, globulins)

Question 14

what should there be none of in the urine if it is being filtered properly?

Answer 14

•Should be no blood or protein measurable in urine if filtering properly

Question 15

• Urinalysis (“dipstick”) can detect what in the urine?

Answer 15

blood

protein

Question 16

How is protein quantification done?

Answer 16

Protein creatinine ratio (PCR)

Question 17

How do we check filtration (excrete out) function?

Answer 17

use estimates of GFR (eGFR) from creatinine blood test

Question 18

How do we assess filtration (keep in) function?

Answer 18

check for presence of blood or protein in urine

Question 19

how do we check the anatomy?

Answer 19

histology

imaging

Question 20

What is the current CKD definition?

Answer 20

• Chronic kidney disease (CKD) is defined by either the presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR<60 ml/min/1.73m2 that is present for ≥3 months

Must have at least 2 samples spaced out by a couple of months to be called chronic kidney disease

Question 21

Prevalence of CKD

Question 22

what is the prevelance of CDK and what does it increase with?

Answer 22

• Increases with age
• ~8-12% UK

Question 23

Why is CKD important?

Question 24

does CDK cost a lot of money?

Answer 24

yes costs lots of money to care for a patient

Question 25

Are numbers for Renal replacement therapy (for end stage renal disease) increasing or decreasing?

Answer 25

Prevalent numbers on RRT are increasing every year Numbers of dialysis not increasing over last few years due to increased transplant

Question 26

what is the mortality of CDK like?

Answer 26

High mortality with patients with chronic kidney disease as often underlying condition hat are increased cardiac risk Increases with worsening renal function

Question 27

Aetiology of CKD

Question 28

what is the aetiology of CDK?

Answer 28

lots of different causes Depends on the population studied Often difficult to establish But if we can find out the cause…could be important to management and outcome

Question 29

what is the clinical approach to dealing with CDK?

Answer 29

* Detection of the underlying aetiology - Treatment for specific disease * Slowing the rate of renal decline - Generic therapies * Assessment of complications related to reduced GFR - Prevention and Treatment * Preparation for Renal Replacement Therapy

Question 30

Clinical assessment

Question 31

What are the symptoms and signs of CKD?

Answer 31

Mainly asymptomatic Often incidentally picked up on blood test for things like diabetes management or in hospital Don’t have signs till very advanced This shows some of the things that someone may have

Question 32

Detection of the underlying aetiology - how is this done?

Answer 32

Question 33

what investigations may be used for the detection of underlying aetiology?

Answer 33

biopsy last, others are for when you dont know exactly what is going on

Question 34

what chemistry investigations can be used to detect aetiology?

Answer 34

–Urea, creatinine, electrolytes (Na, K, Cl) –Bicarbonate –Total protein, albumin –Calcium, phosphate – Liver function tests –Creatine kinase –Immunoglobulins, serum protein electrophoresis

Question 35

what haemotology investigations can be used to detect underlying aetiology?

Answer 35

Full blood count: - Hb - MCV - MCH - WBC - Platelets - % hypochromic RBCs Coagulation screen: - PT - APPT - +/- Fibrinogen

Question 36

what are some urine investigations to detect aetiology?

Answer 36

• Urinalysis (“dipstick”): - Blood - Protein • Protein quantification: - Protein creatinine ratio (PCR) - Albumin creatinine ratio - 24 hour urine collection

Question 37

Renal disease is often __________ – only sign may be abnormal __ or \_\_\_\_\_\_\_\_

Answer 37

asymptomatic BP urinalysis

Question 38

one imaging technique used to detect aetiology is ultrasound, what are the positives of this? and what are the negatives?

Answer 38

Non-invasive No ionising radiation May provide information about chronicity of renal disease No functional data Operator dependant

Question 39

what pathology technique can be used to detect aetiology?

Answer 39

kidney boiopsy

Question 40

Management

Question 41

what are some potential interventions to slowing down the rate of kidney decline?

Answer 41

* BP control \*\*\*\*most important\*\*\* * Control proteinuria (particularly ACE inhibitors / ARBs) * Treat underlying cause * Others

Question 42

Assessment of complications related to reduced GFR - what are some potential ones?

Answer 42

* Acidosis * Anaemia * Bone disease * CV risk * Death & Dialysis * Electrolytes * Fluid overload * Gout * Hypertension * Iatrogenic issues

Question 43

complications ar emor elikely with a wrosening \_\_\_\_

Answer 43

eGFR

Question 44

What is the management of complications related to reduced GFR?

Answer 44

* Acidosis - bicarb * Anaemia – EPO and iron * Bone disease – diet and phosphate binders * CV risk – BP, aspirin, cholesterol, exercise, weight * Death & Dialysis – counsel and prepare * Electrolytes – diet and consider drugs * Fluid overload – salt and fluid restriction, diuretics * Gout – optimise +/- meds * Hypertension – weight, diet, fluid balance, drugs * Iatrogenic issues – BE AWARE

Question 45

Most important thing I think about __ risk as many people will die form that before they reach end stage kidney disease

Answer 45

CV

Question 46

What preperation may be required for end stage renal disease and renal replacement therapy

Answer 46

* Education & information * Selection of modality - HD / PD ?transplant ??conservative care * Planning access * Deciding when to start RRT (renal replacement therapy) * Multidisciplinary team

Question 47

Summary: * CKD is \_\_\_\_\_\_\_ * Kidney function is assessed with ___ (often estimated) in stages * There is a ____ morbidity (RRT, CV events) and mortality * Worse kidney _______ and more _________ is associated with worse outcomes * Early identification and management should ____ rate of decline * In health the kidneys contribute to many ___________ functions – loss of these with ___ leads to many complications including anaemia, acidosis and bone disease. * Good CKD care involves the _____________ team to help manage these complications and help make choices for end stage renal disease and RRT

Answer 47

Summary: * CKD is **_common_** * Kidney function is assessed with **_GFR_** (often estimated) in stages * There is a **_high_** morbidity (RRT, CV events) and mortality * Worse kidney **_function_** and more **_proteinuria_** is associated with worse outcomes * Early identification and management should **_slow_** rate of decline * In health the kidneys contribute to many **_homeostatic_** functions – loss of these with **_CKD_** leads to many complications including anaemia, acidosis and bone disease. * Good CKD care involves the **_multidisciplinary_** team to help manage these complications and help make choices for end stage renal disease and RRT