fluid + electrolyte imbalance

Question 1

ranges of electrolytes

Answer 1

calcium 2.2 - 2.6 mmol/L
magnesium 0.6 - 1 mmol/L
phosphate 0.87 - 1.45 mmol/L
potassium 3.5 - 5.3 mmol/L
sodium 133 - 146 mmol/L

Question 2

SEs of low and high K, Na, Ca

Answer 2

hypokalaemia - muscle cramp, rhabdomyolysis, fatigue, arrhythmia, palpitations

hyperkalaemia - fatigue, numbness, chest pain, SOB, palpitations

hyponatraemia - nausea, headache, confusion, fatigue, irritability, seizures

hypernatraemia - thirst, fatigue, confusion

hypocalcaemia - muscle cramps, confusion, depressed, forgetful

hypercalcaemia - muscle cramps, lethargy, confusion, arrhythmias

Question 3

potassium imp points - which drugs cause hypo and hyper

Answer 3

hypokalaemia:
A - aminophylline/theophylline
B - beta agonists
C - corticosteroids
D - diuretics (thiazide/loop)
E - erythromycin/clarithromycin
I - insulin

hyperkalaemia:
T - trimethoprim
H - heparins
A - ACEi/ARBs
N - NSAIDs
K S - k sparing diuretics
B - beta blockers

imbalance in K leads to cardiac SEs like arrhythmias

hypokalaemia predisposes pt taking digoxin to toxicity

Question 4

management of hypokalaemia and hyperkalaemia

Answer 4

mild to moderate hypokalaemia
- oral K replacement - sando-K

severe hypokalaemia
- IV KCL in Nacl

in renal impairment - replace cautiously - risk of hyperkalaemia due to impaired K excretion

acute severe hyperkalaemia (>6.5)
- urgent treatment
- IV calcium chloride 10%/calcium gluconate 10%
- IV soluble insulin 5-10 units with 50ml glucose 50% given over 5-15 mins
- salbutamol (nebs or slow IV injection)
- stop drugs causing hyperkalaemia

mild-moderate hyperkalaemia (>5.5)
- ion-exchange resins used to remove excess potassium (calcium resonium)
- patiromer calcium
- sodium zirconium cyclosilicate

Question 5

sodium imp points

Answer 5

hyponatraemia:
C - carbamazepine
D - diuretics
D - desmopressin/vasopressin
S - SSRI

Certain Drugs Ditch Salt

hypernatraemia:
S - sodium bicarb/chloride
C - corticosteroids
E - effervescent formulations
O - oestrogens/androgens

Salty CEO

hyponatraemia:
mild-moderate - oral sodium bicarb/chloride tabs

severe - IV NaCl

Question 6

hypocalcaemia and hypercalcaemia and hypercalciuria treatment

Answer 6

if dietary calcium intake insufficient:
- calcium supplements with vit D - ADCAL D3

severe acute hypocalcaemia:
- initial slow IV calcium gluconate 10% (arrhythmias if given rapidly)
- follow with continuous IV infusion to prevent recurrence
- calcium chloride but more irritant

severe hypercalcaemia:
- correct dehydration with IV NaCl 0.9%
- stop drugs causing it

• bisphosphonates and pamidronate disodium used
• corticosteroid used if hypercalcaemia due to sarcoidosis or vit D toxicity
• calcitonin used if due to malignancy

hypercalciuria:
- increase fluid intake + bendroflumethiazide
- reduce calcium intake but not severe

Question 7

hyperparathyroidism and treatment

Answer 7

excessive parathyroid hormone - hypercalcaemia, hypophosphataemia, hypercalciuria

SEs: thirst, polyurea, CVD, kidney stones, osteoporosis

affects 2x women as men, most common in 50-60 year old women

1st line treatment for primary hyperparathyroidism - parathyroidectomy surgery
- assess for CVD and fracture risk

drug treatment:
- cinacalcet if surgery inappropriate
- measure vit D levels - supplement if needed
- to reduce fracture risk - bisphosphonate

Question 8

magnesium imp points

Answer 8

Mg - essential in enzyme systems, stored in bones

Mg excreted by kidneys - retained in renal failure - hypermagnesaemia

hypermagnesaemia:
- muscle weakness, arrythmias
- calcium gluconate injection

hypomagnesaemia: often causes secondary hypocalcaemia and hypokalaemia
- symptomatic/severe - IV/IM magnesium sulfate
- asymptomatic/mild - oral magnesium aspartate + citrate - treatment and prevention of mg deficiency
- oral Magnesium glycerophosphate licensed for hypomagnesaemia

Question 9

phosphate imp points

Answer 9

hypophosphataemia:
- oral phosphate supplements
- common in alcohol dependence or severe dka

hyperphosphataemia:
- phosphate binding agents (calcium based or non-calcium agents)
- in pts with stage 4/5 CKD - manage diet + dialysis before starting agents
- 1st line calcium acetate (calcium based)
- 2nd line sevelamer (non Ca based)
- 3rd line Calcium carbonate (calcium based) or sucroferric oxyhydroxide (non-calcium based)
- 4th line - lanthanum (non Ca based) - only considered if other Phosphate binders cannot be used

can combine Ca based with non Ca based phosphate binder