Renal Failure

Question 1

Key roles of the kidneys

Answer 1

• Elimination of waste products- norma GFR >120ml/min
• control of fluid balance
• regulate acid-base balance
• produce hormones
• regulate electrolytes

Question 2

Stages of AKI

Answer 2

Look at creatinine and urine output. Either or

1: Creatinine 1.5-1.9x baseline; UO <0.5ml/kg/hr for 6-12 hours
2: Creatinine 2-2.9x baseline; UO <0.5”” for >12 hours
3: Creatinine 3x baseline; <0.3ml >24hr or anuria >12

Question 3

Baseline risk factors for AKI

Answer 3

• CKD, DM, >75years old, CHF, liver failure, nephrotoxic (NSAIDs, ACEi, gentamicin, diuretics) medications, past history of AKI,
• Acute illness (sepsis, hypovolemic, hypotension, high EWS)
• Surgery: emergency surgery, intraperitoneal, CKD, diabetes, CHF, age >75, toxic medications

Question 4

Types of AKI with examples

Answer 4

Pre renal: hypovolemic, hypotension, cardiogenic shock (low output), haemorrhage, severe renal artery stenosis

Renal: ATN following pre renal cause, RPGN, acute interstitial nephritis, nephrotoxic drugs

Post renal: Obstruction/blockage (cancer, stone), prostatic hypertrophy, urinary retention (hydronephrosis)

Question 5

General approach to AKI

Answer 5

Identify at risk patients
Stop nephrotoxic agents
Assess volume status (rehydrate or restrict)
monitor creatinine and UO
Urinaylsis, electrolytes, blood, protein
Blood tests
revise drugs
Diet, restrict with Ca/Po4

Question 6

CKD defintion

Answer 6

Abnormality of kidney structure or function present for greater than 3 months with health implications.

Is based on cause, GFR an albuminuria

Question 7

Insulin clearance

Answer 7

Gold standard of measuring GFR
Not reabsorbed or secreted in tubule, used to inject insulin into blood, and measure clearance in urine.

Invasive, used in research

Question 8

Isotope clearance

Answer 8

Infuse radioactive substrate in blood and measure volume degradation. Very accurate. Maybe used in kidney donors.
51Cr-EDTA/125I-IOT
Labour intensive

Question 9

Creatinine clearance and catch to it

Answer 9

Easiest way to measure GFR. Estimate
Urine Cr x Urine volume/ serum creatinine x time period

Reflects body size and muscle mass: smaller people may have lower CrCL but normal for them, vice versa for larger muscular person.

Question 10

CKD and CrCL

Answer 10

Confounds creatinine clearance. As GFR declines, extrarenal creatinine excretion increases, so over estimates GFR

Question 11

How do we estimate GFR now easily?

Answer 11

Formula
Cockcroft and Gault
CKD-EPI formula, used more commonly. Will have standardisations for sex, age etc

Question 12

CKD stages and eGFR

Answer 12

1: >90ml/min
2: 60-90
3: 30-60
4: 15-30
5: <15

Question 13

Albuminuria stages IN CKD

Answer 13

A1: 30mg/mmol
A2: 30-300mg/mmol
A3: > 300mg/mmol

Question 14

Renal function and age

Answer 14

Renal function declines with age, important to note a low GFR as older is only important if has health implications or persistent declining fuction

Question 15

CKD sociodemographic risk

Answer 15

Age, male>female, smoking, low income, Maori/Pacific Islands or Asian, obesity

Question 16

Causes of CKD

How progression typically occurs

Answer 16

Diabetic nephropathy 40%
Glomerulonephritis 30%, IgA nephropathy
HT nephrosclerosis 15%
PCKD 5%

Lack of control of primary disease accelerate progression to ESKD (end stage). Typically secondary factors are what cause the progression

Question 17

Secondary factors that progress CKD

Answer 17

HT, systemic and in glomeruli
Glomerular hypertrophy
Calcium + phosphate
Dyslipidaemia
Proteinuria
Toxicity of ammonia, iron

Question 18

Hypertension in CKD patients
Aim
Changes that can be made

Answer 18

140/90mmHg for most part, even lower if possible
Lifestyle: weight loss, exercise, stop smoking, salt restriction, alcohol moderation.
DRUGS
RAAS blockers: ACEi, A2A, aldosterone antag
SNS block: BB, CCB, AB
Diuretics: thiazide, loop

Question 19

how to modify proteinuria and why

Answer 19

Proteinuria important prognostic factor.
Modify by: weight loss; ACEi + A2A, statins, protein restriction
ACEi most effective in CKD, first line

Question 20

Why improving Ca/PO4 important

Answer 20

At about Stage 3 CKD, serum phosphate increases, with secondary hyperparathyroidism. This accelerates damage, and even cause ectopic deposition.

Returning to normal will slow progression. Limit dairy/nuts, and phosphate. Can use phosphate binders such as calcium carbonate, AlOH3. Aim for less than 4.5

Question 21

Kidney as an endocrine organ

Answer 21

Epo, 1,25(OH)2 vit D (can give calcitriol in CKD/ESKD pateints), BMP-7, renin, A, bradykinin

Question 22

Acid base regulation role of kidney and CKD

Answer 22

In CKD a metabolic acidosis may occur, due to less excretion of non organic acids. Can use oral sodium bicarbonate if need be

Question 23

Uraemia and its manifestations

Answer 23

Occurs with organ dysfunction, resembles sytemic intoxication. No single molecule causes the symptoms. typically stage 4/5 CKD

Neural: Lethargic, fatigue. Seizures
Haematological: Anaemia, bleeding and infection tendency
CV: Pericarditis*, HT, IHD, HF
Pulmonary: Pleuritis, pleurisy
GIT: Nausea/vomiting, anorexia
Metabolic: glucose intlerance
Skin: itching, pigementation
Pyschological: depression/anxiety

Question 24

CKD management

Answer 24

Treating primary and secondary disease and avoiding nephrotoxic drugs.
Correcting abnormailities etc

Question 25

CKD treatment options

Answer 25

Conservative, leave it, many drugs, palliative care.

Dialysis: Haemodialysis or peritoneal. Expensive

Renal transplant: best qol after