Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y3 Medicine > Electrolyte Abnormalities > Flashcards

Electrolyte Abnormalities Flashcards

1
Q

what is hyponatraemia?

A

sodium < 135 mmol/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the presentation of hyponatraemia?

A
  • anorexia
  • nausea
  • malaise
  • headache and irritability
  • decreased GCS and confusion
  • weakness
  • seizures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the main causes of hyponatraemia?

A

SIADH
diuretics - esp thiazide
heart failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how is hyponatraemia sub-categorised?

A
  • hypotonic (inc hypovolaemic, euvolaemic and hypervolaemic)
  • isotonic
  • hypertonic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is hypotonic hyponatraemia caused by, generally?

A

an increase in intravascular volume (but the subcategories are based on total body water differences)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

describe hypovolaemic hyponatraemia

A

there is a deficiency in both total body water and sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe the pathophysiology of hypovolaemic hyponatraemia

A

low fluid volume due to decreased total body water causes ADH release. ADH causes water retention which increases intravascular volume (even though total body water is decreased), diluting the Na.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what are the causes og hypovolaemic hyponatraemia?

A
  • diuretics (thiazide)
  • intrinsic renal disease
  • mineralocorticoid deficiency (Addison’s disease)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

describe euvolaemic hyponatraemia

A

total body water remains the same but water moves into the intravascular space, diluting the sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the causes of euvolaemic hyponatraemia?

A

SIADH - causes increased resorption of water by the kidney (can be euvolaemic or hypervolaemic)
iatrogenic (surgery causes impaired water excretion, certain types of surgical procedures)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe hyervolaemic hyponatraemia

A

excess total body water means that there is also excess intravascular fluid, causing dilution of sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the causes of hypervolaemic hyponatraemia?

A
  • chronic renal failure
  • congestive heart failure
  • liver cirrhosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is redistributive hyponatraemia?

A

hypertonic hyponatraemia
- hypertonic blood with excess osmolytes causes water to shift from the intracellular to the extracellular compartment (into blood), diluting the extracellular sodium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what can cause redistributive hyponatraemia?

A

hyperglycaemia

or administration of hypertonic fluids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is pseudohyponatraemia?

A

isotonic hyponatraemia

= artefact produced by high serum lipid or protein levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what investigations are carried out in a patient with hyponatraemia?

A
  • serum sodium concentration
  • U&E
  • creatinine
  • glucose
  • serum osmolality
  • urine sodium concentration - SIADH
  • CT brain, chest, abdomen/pelvis (malignancy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the management of hyponatraemia?

A 
acute (<48 hours):
- hypertonic (3%) saline (give in 100 ml increments - up to 300 ml initially over 10 mins)
- treat underlying cause 
chronic:
hypovolaemic:
- give isotonic fluid (250 - 1000 ml boluses to maintain BP)
- treat underlying cause 
hypervolaemic:
- fluid restriction - 1 L/day 
- treat underlying cause
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what rate of correction of sodium is aimed for in hyponatraemia and why?

A

up to 8 mmol/L/day correction over 24 hours

- to avoid central pontine myelinolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is SIADH?

A

body produces too much ADH, which causes excess retention of water by the kidneys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the normal action of ADH?

A
  • produced by the hypothalamus and released from the posterior pituitary
  • acts on aquaporin 2 receptors in the distal convoluted tubule, increasing the number of aquaporin receptors on the apical surface of cells and increasing water reabsorption
21
Q

what are the causes of SIADH?

A
  • brain injury (meningitis, subarachnoid haemorrhage)
  • malignancy - small cell lung adenocarcinoma can produce ADH
  • drugs - carbamazepine/SSRIs/amitriptylline
  • infectious - lung/cerebral abscess/ atypical pneumonia
  • hypothyroidism
22
Q

what are the symptoms/signs of SIASH?

A

symptoms and signs of hyponatraemia

  • anorexia
  • nausea
  • malaise/weakness
  • irritability / headache
  • low GCS
  • confusion
  • seizures
23
Q

what investigations are carried out when suspecting SIADH?

A
  • fluid status
  • serum sodium (hyponatraemia <135)
  • serum potassium and cortisol (considering Addison’s disease as alternative cause of hyponatraemia)
  • plasma osmolality (reduced)
  • urine osmolality (high due to water reabsorption)
  • urine sodium concentration (high due to water reabsorption (>40 mmol/L - normal is 20))
  • TFTs - hypothyroidism is a cause of SIADH
  • imaging (e.g. CXR for cancer - can be a cause of SIADH)
24
Q

how would you manage SIADH?

A
  • treat underlying cause
  • fluid restriction
  • replace Na - IV or orally (careful not to correct Na too rapidly)
25
Q

what is hypernatraemia?

A

serum sodium >145 mmol/L

26
Q

what are the causes of hypernatraemia?

A
  • iatrogenic (most common) -giving hypertonic fluids (patient will be hypervolaemic)
  • dehydration ( burns, diarrhoea vomiting, burns) (patient will be hypovolaemic)
  • diabetes insipidus
27
Q

what are the symptoms of hypernatraemia?

A
  • thirst
  • irritable
  • seizures
  • muscle spasms
  • nausea and vomiting
28
Q

what investigations are carried out when suspecting hypernatraemia?

A
  • full history
  • U&Es
  • FBC - haemoatocrit, to look for dehydration
  • blood osmolarity
  • urine osmolarity
  • urine output
  • imaging (CT head - hypopituitarism which can be causing cranial DI)
29
Q

what is the management of hypernatraemia?

A
  • give 0.45% NaCl if euvolaemic or 0.9% NaCl if hypovolaemic
  • aiming for a 12 mol/L/day decrease in sodium
30
Q

what is hypocalcaemia?

A

serum calcium <2.2 mmol/L

31
Q

what is the presentation of hypocalcaemia?

A
  • mild - asymptomatic
  • paraesthesia
  • carpopedal spasm
  • muscle cramps
  • tetany
  • ckvostek’s sign (tapping the facial nerve in front of the ear below the zygomatic arch causes a muscular spasm)
  • trousseau’s sign (inflating a pressure cuff above systolic BP and keeping it there induces a carpopedal spasm)
  • prolonged QT interval (can lead to heart block or VF)
  • laryngospasm
  • bronchospasm
  • dementia, confusion and papilloedema when prolonged
32
Q

what are the causes of hypocalcaemia?

A
  • hypoparathyroidism (causing decreased Ca absorption)
  • 2ry hyperparathyroidism (caused by low vitamin D levels which causes low Ca levels which leads to hyperparathyroidism)
  • chronic kidney disease (reduced active vitamin D and increase in serum phosphorous levels which binds Ca)
  • acute pancreatitis
33
Q

what investigations need to be carried out when suspecting hypocalcaemia?

A
  • U&E
  • creatinine (renal function)
  • amylase (for pancreatitis)
  • serum phosphate
  • serum PTH levels
  • vitamin D levels
  • ECG to rule out long QT (can occur in hypocalcaemia)
34
Q

how would you manage hypocalcaemia?

A
  • IV calcium gluconate
  • Oral Ca preparations alongside IV
  • Oral vitamin D
35
Q

what are the symptoms of hypercalcaemia?

A
  • Moans (tired, depressed, confused)
  • Groans (constipation, pancreatitis, peptic ulcers)
  • Stones (kidney stones, polyuria)
  • Bones (Muscle and bone aches)
  • polyuria and polydipsia
  • ectopic calcification (deposition of calcium in tissues)
36
Q

what are the causes of hypercalcaemia?

A
  • malignancy most commonly (ectopic production of parathyroid-related peptide or ectopic calcitriol or osteolysis from bone tumours)
  • granulomatous conditions such as sarcoidosis and TB
  • Drugs - thiazide diuretics and vitamin D supplements
  • primary hyperparathyroidism (parathyroid gland adenoma)
  • dehydration (urea raised)
37
Q

what investigations are carried out when suspecting hypercalcaemia?

A
  • serum calcium
  • U&Es
  • PTH levels
  • Vitamin D levels
  • Alkaline phosphatase (bony mets or liver involvement in sarcoidosis)
  • albumin levels - low in malignancy
  • phosphate levels - affected in hyperparathyroidism
  • phosphate levels
  • X-rays - bone abnormalities
38
Q

what is the management of hypercalcaemia?

A
  • treat underlying cause
  • 0.9% saline to flush out the Ca
  • Bisphosphonates IV (to reduce bone turnover)
  • denosumab - used when resistant to bisphosphonates
39
Q

what is the presentation of hypokalaemia?

A
  • asymptomatic when mild
  • weakness (beginning in lower extremities and extending upwards)
  • muscle pain
  • constipation
  • respiratory failure
  • ileus (due to involvement of GI muscles)
  • paraesthesia
  • tetany
40
Q

what are the causes of hypokalaemia?

A
  • renal tubular acidosis
  • hypomagnasaemia
  • K-losing diuretics (bendroflumethiazide, furosemide)
  • high aldosterone levels - hyperaldosteronism (inc Conn’s syndrome), Cushing’s disease, Renal artery stenosis
  • diarrhoea, vomiting (causes alkalosis and therefore hypokalaemia)
  • inadequate K replacement in IV fluids whilst nil by mouth
41
Q

what investigations are carried out when suspecting hypokalaemia?

A
  • U&E
  • Serum bicarbonate
  • Serum glucose
  • Serum magnesium (low Mg)
  • ECG
42
Q

what is seen on an ECG when a patient has hypokalaemia?

A
  • Flat T waves
  • ST depression
  • Prominent U waves
43
Q

how would you manage hypokalaemia?

A
  • mild - potassium replacement (potassium chloride supplements). review after 3 days. if needed, consider repeating replacement. if taking thiazide diuretic consider adding a k sparing diuretic
  • if severe, give Iv K cautiously and slowly (NEVER give IV K as a stat bolus)
44
Q

what is the presentation of hyperkalaemia?

A
  • weakness and fatigue
  • muscle paralysis
  • shortness of breath
  • palpitations/chest pain
  • bradycardia
45
Q

what are the causes of hyperkalaemia?

A
  • ischaemia/necrosis
  • infection
  • trauma - crush injuries
  • autoimmune - SLE
  • acidosis (e.g. in DKA)
  • Addison’s disease (aldosterone low- less K excreted)
  • CKD/AKI
  • K-sparing diuretics (spironolactone, amiloride)
  • ACEi/ARBs
  • neoplasia (tumour lysis syndrome, malignancies)
  • haemolytic anaemia, causing K release from RBCs
46
Q

what investigations are carried out when suspecting hyperkalaemia?

A
  • FBC (normochromic, normocytic anaemia suggests acute haemolysis)
  • U&E
  • capillary blood glucose and plasma glucose
  • ABG (acidosis)
  • Creatinine (renal cause)
  • 24 hr urine output - for renal causes
  • ECG
47
Q

what is seen on an ECG in hyperkalaemia?

A
  • tall tented T waves
  • no P waves
  • wide QRS
  • bradycardia
48
Q

how would you manage hyperkalaemia that is causing ECG changes or K>7 mmol/L?

A
  • Stop medications that can be causing the hyperkalaemia (spironolactone, amiloride, ACEi/ARBs)
  • IV calcium gluconate to protect the heart
  • Insulin and dextrose (causes K to move into cells)
  • sodium bicarbonate if acidotic
  • salbutamol (IV or nebulised) (drives K into cells)
  • calcium resonium + lactulose (binds K in intestines and removes it via faeces)
  • Dialysis - gold standard for removing K from body

Y3 Medicine (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions