electrolytes Flashcards
what are ECG changes suggestive of hyperkalaemia?
tall tented T waves
small P waves
widened QRS leading to sinusoidal pattern + asystole
what are causes of hyperkalaemia?
AKI
metabolic acidosis
DKA
addison’s disease
rhabdomyolysis
cell lysis- tissue necrosis, tumour lysis syndrome, trauma, burns
massive blood transfusion
malignant melanomas
drugs: potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, heparin
what are symptoms of hyperkalaemia?
weakness
palpitations
n+v
paraesthesia
what investigations do you need for hyperkalaemia?
blood tests: UE, Ca, PO4, Mg, digoxin level, VBG
bedside: ECG, fluid balance
how do you manage hyperkalaemia?
if >6.5 or ECG changes:
- calcium gluconate 10% 10ml IV over 5 minutes
repeat up to every 15 mins to max 50ml - actrapid 10 units IV + glucose 50% 50ml IV over 10 mins then glucose 5% 1L IV over 12h
- salbutamol 5mg nebs
- consider calcium resonium resin 15g TDS PO or 30g PR
- monitor K+ 2 hourly
- low potassium diet
what foods are high in potassium?
salt substitutues
bananas
oranges
kiwi
avocado
spinach
tomatoes
what are the causes of hypercalcaemia?
hyperparathyroidism- primary or tertiary
hyperthryoidism
malignancy- squamous cell lung ca - PTHrP causes overproduction of ADH; colorectal adenocarcinoma- paraneoplastic syndromes
dehydration
spurious
sarcoidosis
tuberculosis
addison’s disease
drugs - thiazide diuretics, lithium, excess calcium containing antacids, excess vit D, excess ca supplements
what are symptoms of hypercalcaemia?
bones: bone pain
stones: renal calculi/abdo pain
groans: constipation/abdo pain, n+v
thrones: polyuria, polydipsia
moans: fatigue, depression, confusion
what are examination findings of hypercalcaemia?
dehydration
hyporeflexia
muscle weakness
what are the investigations needed for hypercalcaemia?
blood tests: UE, Mg, PO4, albumin, ALP, PTH, vit D, VBG, myeloma screen
ECG: shortening QT interval
what is the management of hypercalcaemia?
- hold thiazides (+ diuretics if dehydrated)
- rv antacids, lithium, ca+ vit d supplements
- aggressive fluid resuscitation- 3-6L/day
may use furosemide if cannot tolerate this as well
- if refractory or severe neurological or dysrhythmic complications- consider pamidronate 60-90mg IV at 20mg/h (if eGFR<30 then 30mg)
- following rehydration- bisphosphonates (take 2-3 days to work, max effect at 7 days)
calcitonin- quicker effect than bisphosphonates
steroids in sarcoidosis, lymphomas or myeloma w heavy proteinuria
what are the causes of hypocalcaemia?
vitamin d deficiency/osteomalacia
CKD
refeeding syndrome
rhabdomyolysis (initial stages)
hypomagnesaemia - due to end organ PTH resistance
hypoparathyroidism- post surgery
pseudohypoparathryoidism- target cells insensitive to PTH
acute hyperventilation
osteoblastic metasteses
spurious- hypoalbuminaemia, drip arm
alkalosis
acute pancreatitis
alcoholism
drugs- phenytoin, massive blood transfusion
what are symptoms of hypocalcaemia?
tetany: carpopedal spasm, muscle twitch, cramp
fatigue
perioral tingling
paraesthesia
if chronic: depression, cataracts
what are examination findings of hypocalcaemia?
chvostek’s sign- percussion over facial nerve triggers facial spasm
trousseau’s sign - carpal spasm if brachial arery occluded (inflate BP cuff); wrist flexion + fingers drawn together
hyperreflexia
spasm
paraesthesia
what are investigations needed for hypocalcaemia?
blood tests: UE, Mg, PO4, albumin, ALP, PTH, vit D, VBG
ECG: prolonged QT
how do you manage hypocalcaemia?
if <1.9
- 10ml 10% calcium gluconate in 100ml 5% dextrose IV over 10 mins
- then infusion 100ml 10% calcium gluconate in 1L 0.9% N. Saline (or 5% dex at 50-100ml/hr)
- check calcium levels after 6 hours and adjust rate until calcium >1.9
if >1.9
oral replacement- adcal 1.5g 1-2 tablets PO BD
Sandocal 1000 1 tablet PO BD
what is SIADH?
syndrome of inappropriate ADH/vasopressin secretion characterised by hyponatraemia secondary to dilutional effects of excessive water retention. euvolaemic
leads to water retention. volume expansion + dilutional hyponatraemia
what are the causes of SIADH?
malignancy
neurological
infections
drugs
PEEP
porphyrias
what malignancies can cause SIADH?
small cell lung cancer
pancreas
prostate
what are neurological causes of SIADH?
stroke
SAH
subdural haemorrhage
meningitis/encephalitis/abscess
what infections can cause SIADH?
pneumonia
tuberculosis
what drugs can cause SIADH?
sulfonylureas - glimepiride + glipizide
SSRIs, tricyclics
carbamazepine
vincristine
cyclophosphamide
what are investigation results suggestive of SIADH?
urine osmolality inappropriately high in relation to serum osmolality (kidneys should normally dilute urine in setting of low serum osmolality) >100mOsm/kg
urine sodium concentration is typically high due to action of ADH on renal tubules ?40mmol/l
how do you treat SIADH?
slow correction to avoid precipitating central pontine myelinolysis CPM
fluid restriction
demeclocycline- reduces responsiveness of collecting tubule cells to ADH
ADH/vasopression receptor antagonist
what are the causes of raised ALP and raised calcium
bone metastases
hyperparathyroidism
what are the causes of raised ALP and low calcium
osteomalacia
renal failure
what are the causes of raised alp?
LIVER- cholestasis, hepatitis, fatty liver, neoplasia
Paget’s
physiological- pregnancy, growing children, healing fractures
w low ca:
osteomalacia
renal failure
w high ca:
hyperparathyroidism
bone mets
what are the causes of hypokalaemia?
- increased potassium loss:
drugs- thiazides, loop diuretics, laxatives, glucocorticoids, abx
GI losses- d + v, ileostomy
renal causes- dialysis
endocrine- hyperaldosteronism/conns syndrome, cushing’s syndrome - trans-cellular shift
insulin/glucose therapy
salbutamol
theophylline
metabolic alkalosis - decreased potassium intake
- magnesium depletion
what are the symptoms of hypokalaemia?
weakness
cramps
n+v
paraesthesia
what are the ecg findings in hypokalaemia?
prolonged PR
ST depression
flat or inverted T waves
U waves
what blood tests are needed in hypokalaemia?
UE, Mg, Ca, PO4, VBG
predisposes to digoxin toxicity
what is the management of hypokalaemia?
severe <2.5 or symptomatic hypoK- IV replacement w cardiac monitoring. infusion rate should not exceed more than 20mmol/hr
mild-moderate 2.5-3.4 0 oral potassium if no ECG changes
what are the causes of hypovolaemic hyponatraemia?
- renal losses
diuretics
osmotic diuresis - hyperglycaemia
addison’s disease
salt-losing nephropathy - non-renal losses
d + v
fistulae
burns
bowel obstruction
heat
what are the causes of euvolaemic hyponatraemia?
excess salt
polydipsia
severe hypothyroidism
SIADH
- drugs- SSRIs, tricyclics, carbamazepine, opiates, PPI
- lung- infection, tumour
- malignancy
- CNS disease- SOL, infx, inflm
what are the causes of hypervolaemic hyponatraemia?
heart failure
renal failure
liver failure
nephrotic syndrome
what are spurious causes of hyponatraemia?
drip arm
lipaemic sample
hyperglycaemia
what are the symptoms of hyponatraemia?
weakness
cramps
n+v
headache
what investigations are needed for hyponatraemia?
UE, LFT, TFT, glucose, urinary + serum osmolality, urinary sodium
fluid balance chart
what are the causes of hypovolaemic hypernatraemia?
- water loss
osmotic diuresis- hyperglycaemia
sweating, diarrhoea
diabetes insipidus
- nephrogenic- hyperCa, hypok, lithium, demecloycline
- central - pituitary surgery/disease, SOL, HI - poor intake
reduced thirst- hypothalamic disease
what are the causes of euvolaemic hypernatraemia?
excess salt
hyperaldolsteronism
cushing’s syndrome
hypertonic dialysis
what investigations are needed for hypernatraemia?
UE, Ca, glucose, serum + urine osmolalities, urinary Na
gluid balance chart
what are the causes of hypophosphataemia?
GI loss
- d+v, intestinal malabsorption
drugs
- diuretics, insulin, salbutamol, phosphate binders, theophylline, insulin
refeeding syndrome
alkalosis
hyperparathyroidism
post-DKA treatment
alcoholism
what are the symptoms of hypophosphataemia?
tremor
muscle twitch
cramps
weakness
parasthesia
what investigations are needed for hypophosphataemia?
ECG
fluid balance chart
bloods- UE, Mg, Ca, PTH
how do you manage hypophosphataemia?
0.6-0.8- oral tablets TDS
<0.6/ECG changes- IV phosphate polyfusor up to 50mmol (500ml) over 12-24hrs
what are the causes of hypomagnesaemia?
GI loss
- diarrhoea, stoma, intenstinal malabsorption
drugs
- diuretics, PPI, aminoglycosides, ciclosporin, insulin
refeeding syndrome
hypoparathyroidism
critical illness
alcoholism
what are the symptoms of hypomagnesaemia?
tremor
muscle twitch
cramps
weakness
paraesthesia
what are the investigations for hypomagnesaemia?
ECG
fluid balance chart
bloods- UE, Ca, PO4, PTH
how do you manage hypomagnesaemia?
> 0.5- PO replacement TDS
<0.5- IV 16-20mmol magnesium sulphate in 100ml 5% dex over 4-6hrs
