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Renal + Urology > Potassium + calcium > Flashcards

Potassium + calcium Flashcards

1
Q

What causes increased secretion of K+?

A

aldosterone
increased delivery of Na and water
high potassium

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2
Q

What value is classed as hypokalaemia?

A

<3.5mmol/L

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3
Q

Clinical features of hypokalaemia

A

neuromuscular - weakness, constipation, confusion, rhabdo

cardiac - arrhythmias, ECG changes, digoxin toxicity, hypertension

renal - polydipsia/polyuria, metabolic alkalosis

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4
Q

Hypokalaemia ECG changes

A

ST segment depression
flattened T wave
U wave

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5
Q

Hypokalaemia aetiology

A

pseudohypokalaemia
decreased potassium intake/reduced absorption
increased entry into cells
increased GI losses
increased urinary losses

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6
Q

What is pseudohypokalaemia?

A

blood sample with large number of abnormal white cells (eg. AML) - take up extracellular K+ - reduced conc.

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7
Q

What causes increased entry of potassium into cells?

A

insulin - stimulates Na-K ATPase
B2 agonists
alkalosis - metabolic or respiratory
hypokalaemic periodic paralysis

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8
Q

What can cause increased urinary loss of potassium?

A

increased mineralocorticoid activity (primary or secondary hyperaldosteronism)

diuretics - loop + thiazide

renal tubular acidosis

Liddles

Bartters

Gitelmans

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9
Q

Mild-moderate hypokalaemia treatment

A

K3-3.4
oral potassium replacement
(if primary hyperaldosteronism - give aldosterone antagonists)

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10
Q

Severe hypokalaemia management

A

<2.5
IV potassium
10-20mmol per hour via peripheral line
careful ECG monitoring

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11
Q

What potassium level is considered hyperkalaemia?

A

> 5

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12
Q

Hyperkalaemia clinical features

A

asymptomatic
cardiac
weakness - muscle weakness, paralysis of diaphragm

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13
Q

ECG changes in hyperkalaemia

A

mild (5.5-6.5) = peaked T waves, prolonged PR segment

moderate (6.5-8) = loss of P wave, prolonged QRS, ST elevation, ectopic beats

severe (>) = sine wave, VF, asystole, axis deviations, bundle branch blocks, fascicular blocks

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14
Q

Hyperkalaemia aetiology

A

pseudohyperkalaemia
redistribution
reduced renal clearance

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15
Q

What causes pseudohyperkalaemia?

A

movement of K out of cells after specimen taken - eg. fist clenching, mechanical trauma

severe leucocytosis (CLL)

thrombosis (K released from platelet after clotting)

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16
Q

What things cause redistribution that causes hyperkalaemia?

A

increased tissue breakdown - tumour lysis, rhabdo, haemolysis, ischaemia

metabolic acidosis

hyperosmolality and hyperglycaemia

17
Q

What can cause reduced renal clearance leading to hyperkalaemia?

A

mineralocorticoid deficiency
mineralocorticoid resistance
drugs - K sparing diuretics
acute on chronic kidney disease

18
Q

What drugs can induce hyperkalaemia?

A

potassium-containing drugs
beta blockers
ACE-i
ARB
aldosterone receptor antagonist
K-sparing diuretics
NSAID, COX-2i
CNI (calcineurin inhibitors eg. cyclosporin, tacrolimus)

19
Q

Hyperkalaemia treatment

A

monitor if K>6
treat if K>6.5 or ECG changes
calcium gluconate

20
Q

What does calcium gluconate do in hyperkalaemia and how is it given?

A

antagonises membrane effect of K+ (stabilises cardiac membrane)
20ml of 10% calcium gluconate over 10 mins
effect <1h
repeat - max 40ml until ECG normalises

21
Q

What should be given in hyperkalaemia >6.5 or ECG changes?

A

calcium gluconate
insulin-glucose (10 units actrapid in 50ml 50% dextrose over 10mins)
monitor BMs

22
Q

How do you reduce total body potassium?

A

urinary K wasting - diuretics
gut wasting - calcium exchange resins
extracorporeal wasting = haemodialysis or haemofiltration

23
Q

Hypercalcaemia symptoms

A

abdominal pain
vomiting
constipation
renal stones and failure
polyuria
polydipsia
confusion
depression
cardiac arrest (shortens QT interval)

24
Q

Hypercalcaemia treatment

A

treat underlying cause
stop exacerbating drugs
ensure good hydration - IV saline
primary hyperparathyroidism - surgery, calcimimetics
malignancy - treat, bisphosphonates
lymphomas/myeloma.granulomatous- - steroids
furosemide - loop diuretics lose calcium
calcitonin - inhibits osteoclasts
dialysis

25
Q

Hypocalcaemia clinical features

A

paraesthesia
muscle twitching
Trousseau’s sign
Chvostek’s sign
seizures
prolonged QT interval
arrhythmia

26
Q

Hypocalcaemia treatment

A

based on severity and cause
<1.9, symptoms or signs - IV calcium gluconate
>1,9 - oral calcium

correct hypomagnesaemia
Vit D/hypoparathyroidism - vit D

27
Q

Key calcium regulators

A

Vit D
PTH
calcitonin

28
Q

What is corrected calcium corrected for?

A

albumin

29
Q

Calcium functions

A

bone structure
muscle contraction
cellular metabolism
wound healing
nerve impulse transmission

Renal + Urology (36 decks)

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