What Happens When Kidneys Stop Working

Question 1

What happens when kidneys stop working

Answer 1

Loss excretatory function - accumulation of waste products
Loss homeostatic function - electrolyte function, acid base, volume control
Loss endocrine - loss erythropoietin production, failure of 1 alpha hydroxylase vit D
Abnormality of glucose homeostasis - decrease gluconeogenesis

Question 2

Ways to assess kidney function

Answer 2

Urea
Creatinine
Creatinine clearance
Inulin clearance
Radionuclide studies

Question 3

Why is inulin clearance not useful

Answer 3

Complicated and invasive but is the best test, used in labs only

Question 4

What are the cons of creatinine clearance test for kidney function

Answer 4

Affected by muscle mass, race, age

Vary way to much from person to person

Question 5

What are the cons of urea conc test for kidney function

Answer 5

Urea up if urine output down
Up if urea production increase eg GI bleed
Urea down if liver failure
Urea up if catabolic bc on steroids

Urea level vary too much between situations

Question 6

What is eGFR

Answer 6

Estimated GFR using equation and creatinine and patient factors eg age and race

Question 7

What are the pros and cons of radionuclide clearance test for kidney function

Answer 7

Radionuclide version of inulin clearance
EDTA clearance
Reliable but expensive
Used by oncologists when planning chemo regimes

Question 8

Symptoms of renal failure?

Answer 8

Extreme lethargy
Weakness
Anorexia
Clinical volume depleted leading to severe hypotension

Question 9

What is tested and shown in order to diagnose renal failure?

Answer 9

Elevated plasma urea and creatinine

Question 10

What complicates renal failure?

Answer 10

Hypekalaemia
Hyponatraemia
Metabolic acidosis
Anaemia

Question 11

What causes lethargy and anorexia?

Answer 11

FAILURE OF EXCRETION causes nitrogenous waste, hormones, peptides and other middle sized molecules to build up to build up
FAILURE OF HOMEOSTASIS, acidosis, hyponatraemia, volume depletion (low bp)
FAILURE OF ENDOCRINE FUNCTION, anaemia

Question 12

What causes a salt and water imbalance in renal failure? What does that lead to?

Answer 12

Tendency to retain sodium leading to hypertension, oedema, pulmonary oedema, volume depletion (low bp)

Question 13

When can salt and water loss be seen in renal failure patients?

Answer 13

If they have tubulointerstitial disorders in which the concentrating mechanisms have been damaged

Question 14

What causes acidosis in renal failure patients?

Answer 14

Decreased excretion of H+ ions and by retention of acid bases

Question 15

What effect can acidosis have on renal failure patients?

Answer 15

It is buffered by H+ ions passing into cells in exchange for K+ ions therefore aggravates tendency to hyperkalaemia, increases CO2 loss through lungs - kussmahls respiration, exacerbates anorexia and increases muscle catabolism

Question 16

What causes hyperkalaemia in renal failure patients?

Answer 16

Failure of distal tubule to secrete potassium

Question 17

What exacerbates hyperkalaemia in renal failure patients?

Answer 17

Acidosis - causing shift of K+ from intracellular to extracellular space

Question 18

What can hyperkalaemia cause in renal failure patients?

Answer 18

Cardiac arrhythmias (loss of p waves and bradycardia) and arrest, affect neural and muscular activity

Question 19

What are clinical features of hyperkalaemia dependent on?

Answer 19

Chronicity of the hyperkalaemia

Question 20

Why can severe hyperkalaemia sometimes lead to heart block?

Answer 20

Increase plasma K+ can lead to membrane depolarisation, which can be large enough that a portion of Na channels inactivate so can’t contribute to AP upstroke leading to less conduction and excitability

Question 21

How can severe hyperkalaemia lead to bradycardia?

Answer 21

Depolarisation due to increased plasma K+ can lead to reduced SA nodal cell upstroke leading to less firing rate

Question 22

What does a lower erythropoietin production in renal failure lead to?

Answer 22

Anaemia

Question 23

What does low 1-25 Vit D levels result in in the long and short term?

Answer 23

Poor intestinal calcium absorption
Short term = hypocalcaemia
Long term = hyperparathyroidism

Question 24

What is a major predictor of end stage renal failure?

Answer 24

CKD - chronic kidney disease

Question 25

What is a major outcome for patients with CDK?

Answer 25

Cardiovascular disease

Question 26

How is a renal failure patient initially managed?

Answer 26

Intravenous normal saline to correct fluid depletion
Intravenous sodium bicarbonate to correct acidosis
Intravenous insulin and dextrose to lower plasma potassium by driving back in cells
Transfer to CX for dialysis

Question 27

Traditional ways to assess GFR?

Answer 27

Urea
Creatinine
Creatinine clearance
Inulin clearance
Radionuclide studies

Question 28

How to estimate GFR => serum creatinine?

Answer 28

1. modification of diet in renal disease MDRD

2. CKD epidemiological collaboration CKD-EPI - better estimate true DFR at >45mL/min

Question 29

How is renal failure managed long term?

Answer 29

Haemodialysis for 4 hrs 3x a week
Low K+ diet and fluid restriction
Erythropoietin injections to correct anaemia
1,25VitD supplements to prevent hyperparathyroid bone disease

Question 30

What is osmotic diuresis

Answer 30

the increase of urination rate caused by the presence of certain substances in the small tubes of the kidneys. The excretion occurs when substances such as glucose enter the kidney tubules and cannot be reabsorbed (due to a pathological state or the normal nature of the substance)