Renal Dysfunction

Question 1

Why is urine normally clear/ amber coloured?

Answer 1

Urobilinogen - breakdown product of haemoglobin

Question 2

What does SG stand for?

Answer 2

Specific gravity? 1003-1030

Question 3

pH of urine?

Output?

Answer 3

5-6.5 (due to hydrogen)

0.5ml per kg per hour

Question 4

What is the composition of urine?

Answer 4

96% water
2% urea
others: creatinine, ammonia, sodium, chlorides, sulphates, potassium

Question 5

Dip stick?

Lab tests?

Answer 5

Variety of info about urine e.g. SG, nitrates, bilurubin, urobilinogen, proteins etc.

Urine specific gravity test - lab

1.003-1030 is normal range
Above 1030 = dehydration, higher = more dehydration
Why? Sweating,

SG- pneumonia - fast resp rates

Question 6

What causes high Specific gravity?

Answer 6

Increased concentration of solutes...
Anything that makes you dehydrated:
- sweating 
- temperature
- fast respiratory rates
- UTI - more urination, dehydration
- decreased renal blood flow (poor perfusion to kidney)
- Excessive ADH secretion (anti-diuretic hormone)

Question 7

What does HIGH specific gravity indicate?

Answer 7

You have extra substances in your urine e.g.
- 
- 
- 
-

Question 8

What does LOW specific gravity indicate?

Answer 8

Decreased concentration of solutes:

• Renal Failure
• Pylophrenitis
• Diabetus insipidus*
• Acute tubular necrosis*
• Interstitial nephritis

Question 9

What is diabetes insipidus?

Answer 9

Condition where you produce large amounts of urine, feel thirsty,

AKA POLYURIA
POLYDIPSIA

Question 10

What is Acute tubular necrosis/

Answer 10

Acute tubular necrosis (ATN) is a medical condition involving the death of tubular epithelial cells that form the renal tubules of the kidneys. ATN presents with acute kidney injury (AKI) and is one of the most common causes of AKI. Common causes of ATN include low blood pressure and use of nephrotoxic drugs.

Question 11

What does Urine Osmolarity measure?

Answer 11

Number of dissolved particles in urine
It’s more accurate than SG

Useful in diagnosing diabetes insipidus, diagnosing dehydration status

Question 12

What can high Urine Osmolarity indicate?

Answer 12

• Congestive Heart Failure
• Dehydration
• Acute Kidney Injury
• High glucose

Question 13

What can LOW Urine Osmolarity indicate?

Answer 13

• Excessive fluid intake
• Kidney failure
• Renal tubular necrosis

Question 14

What should urine not contain (measured on dipstick)

Answer 14

• Proteins (proteinuria)
• Albumin (albuminuria)
• Red blood cells (haematuria) (small amount = grey /smokey)
• White blood cells

(they’re too large particles)

• glucose (glycosuria)
• keytones - associated with weight loss & diabetes
• nitrites -

Question 15

Urinary tract infection - what is urine like?

What is the most common cause?

What CAN show on dipstick?

Answer 15

Smelling bad - bacteria acting on urea to increase ammonia levels
Cloudy urine - due to exudate (infection, increased calcium or phosphates)

90% of UTIs are caused by Gram Negative Bacteria which produce nitrate reductase, an enzyme that breaks down nitrate

Dipstick - nitrites CAN show

Question 16

When WBC count is high?

Answer 16

= inflammation in urine or

Bacterial UTI - bladder or kidney infection

Question 17

Lab tests - serum blood

Renal disease - mega principle?
- elevated electrolytes e.g. potassium, sodium
- elevated urea in bloods
- elevated creatinine in bloods
-

Answer 17

ACIDOSIS

Question 18

Urine Osmolarity

• normal range
• what does lower score mean?

Answer 18

Normal is 270-300 mOsm/kg water

Lower - fewer particles in urine - less concentrated
associated with overhydration, oedema

Higher - ADH (antidieretic hormone)
deficient fluid volume, dehydrated

Question 19

Hypovoalemic Shock - definition

Answer 19

Hypovoalemic shock refers to a medical or surgical condition in which rapid fluid loss results in multiple organ failure due to inadequate perfusion/ poor oxygen delivery

Question 20

Hypovoalemic Shock

Answer 20

Pre-renal renal failure cause of AKI

Question 21

Two forms of Hypovoalemic Shock - define!

Answer 21

‘Absolute’ is due to a lower circulating blood volume for a given vascular capacity e.g Hemorrhage, trauma,post op bleeding

‘Relative’ is expanded vascular capacitance for a given blood volume e.g sepsis, anaphalayxis, drops BP, drops perfusion, … internally hypovoalemic

Question 22

Hypovoalemic Shock - relevance

Answer 22

In almost all medical and surgical emergencies, consider hypovoalemia to be the primary cause of shock until proven otherwise. RCUK 2015

By far the most common type of shock in children

Question 23

Shock and Blood pressure

Answer 23

Urine output reflects to a degree your caridovascular function - reflective of cardio output - perfusion to kidney is good

Perfusion poor (due to shock) - may have symptoms of renaldysfunction

Question 24

When should you be worried about urine output?

Answer 24

When is less than 0.5ml/kg/hour, AKA oliguria

Question 25

When should you be worried about urine output? (as a principle)

Answer 25

When is less than 0.5ml/kg/hour, AKA oliguria

Question 26

How is urine produced?

Answer 26

Via glomerular filtration (125ml per min) Relies on relatively high perfusion pressure within the glomerular capillary and adequate blood flow

Question 27

What autoregulates urine output?

Answer 27

Pre-glomerular afferent arteriole until the mean arterial pressure falls below 80

Question 28

What regulates urine output when blood pressure is low?

Answer 28

Hormonal control - (renananti intensive system? mystery word) e.g. Aldosterone ADH - Anti-dieretic hormone

Question 29

Why does urine output fall when perfusion to kidney is reduced?

Answer 29

Renal system responds to shock by stimulating an increase in RENIN secretion from the juxtaglomerular apparatis. Renin converts angiotensin to angiotensin 1, which is subsequently converted to angiotensin 2. --> vasoconstriction and stimulation of aldosterone ... leads to SALT & WATER conservation - retain instead of excrete.

Question 30

What are the 2 x main effects of angiotensin 2?

Answer 30

Vasoconstriction of arteriolar smooth muscle and stimulation of aldosterone secretion by the adrenal cortex.

Question 31

ADH (anti-diretic hormone) Where is is released from, and when? What does it do?

Answer 31

ADH is released from the posterior pituitary gland in response to a decrease in BP (detected by baroreceptors) and a decrease in SODIUM concentration (as detected by osmorecepetors) Indirectly leads to an increased reabsorption of water and salt by the distal tubule, the collecting ducts, and the loop of Henle

Question 32

Critical pressure ?

Answer 32

pressure less than 65 (or sometimes lower than 80) - > will produce kidney injury

Question 33

Triad of three variables freq. mentioned in pathophysiology world

Answer 33

Cardiac output - reflects cardio function, normal is stroke*rate = 5 cardio output - falls pH - normal is 7.35-7.55 - renal prob=acidotic aerobic to anaerobic -> lactic acid, c02 functions as acid PaO2 - normal 11-14 kilopascals Hypovoalemic shock - lose red blood cells, less capacity, o2 falls

Question 34

What amount of cardiac output goes to kidneys each minute?

Answer 34

20-25%

Question 35

1999 Goldhill

Answer 35

Respiritatory rate is the most sensitive predictor of impending deterioration and that rate, depth and ease of respiriations needs to be assessed BUT - poor urine output VERY important

Question 36

Hypovoalemic shock - exists as a spectrum, Early? Late?

Answer 36

Early - subtle pathophysiological tissue insults Late - multi-system organ dysfunction

Question 37

How to assess hypovoalemic shock?

Answer 37

(Assess for safety, PPE, early call for help) Airway: Breathing(LLF): fast resp due to acidosis (phrenic nerve stimulation), Circulation: decreased blood pressure (cardiovascular collapse) cold hands (poor perfusion), poor urine output due to poor perfusion Increased HR due to adrenaline release Increased blood glucose - glycogen->glucose in liver, tehn released. Nausea and vomitting due to pain OR blood redirection to major organs (big GI changes- ++fluid) Disability: Consciousness impaired due to hypoxia Exposure:

Question 38

Objective way to assess hypovoalemic shock?

Answer 38

Full blood count, repeated a few hours on. If red blood cells count remains the same, can't be bleeding