Acid Base Balance And AKI

Question 1

How does alkalemia lower free calcium?

Answer 1

1. High pH causes a low H+ concentration
2. Albumin donates H+ from its carboxyl groups and becomes negatively charged
3. Serum Ca2+ binds to albumin, reducing it in free circulation

Question 2

What are the symptoms of alkalemia that arise due to a drop in free calcium?

Answer 2

Muscle twitches,
Numbness and tingling,
Tetany and paralysis of respiratory muscles.

Question 3

How does acidosis increase free calcium?

Answer 3

More H+ bound to albumin means that calcium cannot bind or is displaced.

Question 4

What calcium related signs occur in acidemia?

Answer 4

Arrhythmias,

Denaturing of proteins too, but this isn’t a sign obviously, stupid question lol 😝

Question 5

What percentage of acid base regulation occurs at the kidney?
How long does this regulation take to occur?

Answer 5

25% (75% lungs)

1-2 days

Question 6

What mechanism occurs in the proximal convoluted tubule epithelial cells to buffer urine?

Answer 6

Breakdown of glutamine into ammonia which diffuses freely over the membrane into nephron and binds H+ ions, becoming ammonium ions that cannot cross the membrane back.

Question 7

What titratable buffer is found in the nephron?

Answer 7

Hydrogen phosphate HPO2- (forms H2PO4-)

Question 8

How do alpha intercalated cells help reduce acidosis?

Answer 8

Bicarbonate ions produced in the cell are exchanged for chloride ions in the blood to increase buffering.
Hydrogen ions are excreted into tubular lumen in exchange for potassium

Question 9

How do beta intercalated cells help reduce alkalosis?

Answer 9

Produce H+ from H20 and C02 in the cell via carbonic anhydrase enzyme. H+ then selectively reabsorbed into the blood, exchanged for potassium.

Question 10

What can all cells do to help buffer pH changes?

Answer 10

Exchange potassium for hydrogen, in each direction.

Question 11

Acidosis is intrinsically linked to which type of potassium imbalance?
Which is alkalosis linked to?

Answer 11

Acidosis - hyperkalaemia

Alkalosis - hypokalaemia

Question 12

How is respiratory acidosis caused?

What is it associated with?

Answer 12

CO2 retention reacting with water to produce H+,

Alveolar hypoventilation and raised pCO2

Question 13

How is respiratory alkalosis caused?

Answer 13

Hyperventilation increases excretion of CO2, lowering pCO2

Often caused by excessive artificial ventilation

Question 14

How is metabolic acidosis caused?

Answer 14

Raise in H+ outside of the respiratory pathways, such that metabolic input exceeds excretion

Question 15

How can the body compensate for metabolic acidosis?

Answer 15

Respiratory - increased ventilation

Renal - secretion of H+ at DCT and CD, reabsorption of HCO3-

Question 16

What is the anion gap?

What is the normal range for the anion gap?

Answer 16

Difference between measured (not all) anions and cations.

Normally 10-18mmol/L

Question 17

How can you tell if there is a renal cause for acidosis?

Answer 17

Anion gap remains unchanged. HCO3- is not produced in great enough quantities but is replaced by Cl-, which is also a measured anion

Question 18

What causes metabolic alkalosis?

Answer 18

Excessive vomiting - excretion of H+ ions in form of stomach acid. Excessive bicarbonate or antacid ingestion.

Question 19

What respiratory compensation is there for metabolic alkalosis?
What renal compensation exists?

Answer 19

Hypoventilation (CO2 retention produces more H+ but also HCO3- that must be excreted)
HCO3- not absorbed in proximal tubule
HCO3- secreted at DCT/CD and H+ reabsorbed

Question 20

What is uraemia?

Answer 20

Build up of nitrogenous waste in the bloodstream (Particularly urea and creatinine). Caused by poor filtration by the kidneys

Question 21

What is AKI?

Answer 21

deterioration of renal function occurring over hours or days

Question 22

What features are associated with AKI?

Answer 22

Urea and creatinine raise rapidly,
Oliguria (low urine production),
Often reversible.

Question 23

What are pre renal causes for AKI?

Answer 23

decreased blood flow:
Portal hypertension,
Hypovolaemia,
Shock,
Renal artery stenosis

Question 24

Which drugs increase incidence of pre renal causes of AKI by impairing renal auto regulatory systems?

Answer 24

NSAIDS and ACEi

Question 25

What intrinsic causes are there for AKI?

Answer 25

Any damage to kidney:
Acute tubular necrosis and ischaemia,
Rhabdomyolysis,
Glomerular disease,
Acute interstitial nephritis.

Question 26

What are post renal causes of AKI?

Answer 26

Outflow obstruction:
BPH or urethral stricture,
Tumours,
Bilateral kidney stones,
Retroperitoneal fibrosis causing urethral obstruction.

Question 27

What investigations should be done in acute bladder injury?

Answer 27

Urine dipstick: culture, cytology and microscopy.
Blood test - U and E
X-ray kidney, ureter, bladder
Ultrasound renal tract.

Question 28

What biochemical changes occur in AKI?

Answer 28

increase in plasma urea and creatinine concentration
increase in plasma potassium
icrease in plasma phosphate and plasma calcium

Question 29

What symptoms indicate a pre renal cause of AKI?

Answer 29

Thirst
Weight loss
Hypotension
hypovolaemia

Question 30

What symptoms indicate intrinsic cause of AKI?

Answer 30

hypertension
Proteinuria
Haematuria
Previous normal urinalysis

Question 31

What symptoms indicate post renal AKI?

Answer 31

Frequency,
Hesitancy,
Crystalluria,
Distension of bladder or enlarged prostate.

Question 32

What are the life threatening complications of AKI?

Answer 32

Hyperkalaemia,
Pulmonary oedema,
Bleading.

Question 33

How might obstruction of bladder outflow be managed?

Answer 33

Urinary or suprapubic catheter. If ureters are obstructed, nephrostomy tube may be inserted