electrolytes Flashcards
(49 cards)
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
