Electrolyte disturbances Flashcards
(10 cards)
Hypokalaemia:
- Definition
- Symptoms (7)
- ECG changes (4)
- Treatment
- Causes (pseudo, extra-renal, renal, hormonal)
- Describe how it affects the action potential
Hypokalaemia:
- Definition: <3.5
- Symptoms (7): fatigue, muscle weakness, constipation, arrhythmias, htn
- ECG changes (4): peaked p, inc pr, small flattened t, u wave
- Treatment: oral k if >2.5, if <2.5 iv 0.9% nacl + k 40mmol x3 - if mg deficient replace this first as hypomag decreases k absorption
- Causes (pseudo, extra-renal, renal, hormonal):
Pseudo: leukaemia
Extra renal: reduced intake, diarrhoea/ ileostomy, hyperaldosteronism, cushings (think also will have htn in endocrine ones)
Renal: diuretics, steroids, hypomagnesia
Other: refeeding, vigorous exercise, insulin, b agonists
Tends to associated with acidosis (dirrhoea, renal tubular acidossis, acetazolamide, dka)
Also can with alkalosis (vomiting, thiazides, cushings, conns)
- Describe how it affects the action potential: dec conc outside cell means k channels work less causing delay in repolarisation hence lengthening AP which can lead to early after depolarisations hence excitement of myocytes
Hyperkalaemia:
- Definition
- ECG changes (4)
- Treatment (5)
- Causes (6)
- Describe how it affects the action potential
Hyperkalaemia:
- Definition: >5.5
- ECG changes (4): p flattening, wide qrs, tall tented t, slurring st - then becomes a sin wave
- Treatment (5): only treat if >6.5 or ecg changes
Ca gluconate 10% 30ml over 5-10mins stabilises myocardium otherwise VF
Iv insulin actrapid 10 units: shifts k into cells
IV dextrose 50ml 50%
Salbutamol 10mg neb
Ca resonium dec absorption
NaHco3 if acidotic
- Causes (6): k rich diet, ckd, addisons, aki, dka, acei/spironolactone/nsaids/amiodarone, rhabdo
- Describe how it affects the action potential: dec conc grad means cell deps and na channels inactivate causing slower ap upstroke dec AP
Hypernatraemia:
- Definition
- Symptoms (6)
- Causes (hypervolaemic, hypovolaemic, euvolaemic)
- Treatment
- Complications (2)
Hypernatraemia:
- Definition: >146
- Symptoms (6): thirsty, irriable, weak, confusion, seizures, hyperreflexia
- Causes (hypervolaemic, hypovolaemic, euvolaemic)
Hypervol: hyperaldosteronism, cushings, hypertonic dialysis
Hypovol: sweating, burns, d+v, loop, renal disease
Euvol: diab insipidus
- Treatment: iv fluids
- Complications (2): dehydration, thrombosis
Hyponatraemia:
- Definition
- Symptoms
- Causes (pseudo, hypovolaemic, hypervolaemic, euvolaemic)
- Investigations
- Treatment
- Complications (4)
Hyponatraemia:
- Definition: <135
- Symptoms: n+v, headaches, confusion, lethargic, seizures, irritable, ataxia
- Causes (pseudo, hypovolaemic, hypervolaemic, euvolaemic)
Hypovolaemic: (urine na>20 means renal loss: thiazides, addisons). (urine <20: burns, sweating, pancreatitis, dirrhoea)
Hypervolaemic: nephrotic, chf, liver failure
Euvolaemic: siadh, primary polydipsia, hypothyrodism
Pseudo: hyperlipidaemia
- Investigations
1. assess fluid status
2. plasma + urine osmolality
- Treatment
Acute <48 hours: if symptomatic 3% hypertonic saline on HDU
Chronic: If hypovol then normal 0.9% nacl. If hypervol then fluid restrict. If euvol restrict fluid to 500-100 - Complications (4): seizures if untreated (sudden shift into cell causing cerebral oedema), resp distress, central pontine osmotic demyelination (aim to correct <12 mmol day)
SIADH:
- Definition
- Causes (7)
- Symptoms (5)
- Investigations
- Management
SIADH:
- Definition: inc release ADH (post pit) inc h20 absorption in kidneys
- Causes (7): post op, pneumonia/tb, haemorrhage head, ssris, carbamazepine, sclc, meningitis
- Symptoms (5): n+v, headaches, muscle aches, drowsy, seizures
- Investigations: diagnosis of exclusion - review diuretics, cortisol, recent d+V, failure of organs. Urine osm is high and urine na conc is high/
- Management: 800ml fluid restrict, tolvaptan, demeclocycline, oral nacl
Diabetes insipidus:
- Definition
- Causes
- Main DD
- Symptoms (3)
- Investigations
- Management
Diabetes insipidus:
- Definition: dec ADH causing inc h20 reabsorption
- Causes
Cranial: dec synthesis (trauma, tumour, tb, meningitis, sarcoidosi, haemochromatosis)
Nephrogenic: resistance (congen, lithium, hypokal, hypercalc, pckd)
- Main DD: primary polydipsia
- Symptoms (3): polyuria, dipsia
- Investigation: high plasma os, low urine os <700, water deprivation test
- Management: for cranial desmopressin injection. For nephro salt + protein restriction, thiazides
Hypercalcaemia:
- Definition
- Causes (6)
- Symptoms (5)
- Investigations
- Treatment of hyperparathyroidism
- Complications
Hypercalcaemia:
- Definition: >2.6
- Causes (6): primary hyperpara, malig (parathy adenoma), familial hypocalciuric hypercalc (defect in ca sensing rec dec ca: creatinine), pthrp in squamous lung ca + RCC (dec PTH), thiazides, tb, ckd
- Symptoms (5): stones, moans, groans abdo, bones, polyuria/dipsia, shortened qt
- Investigations: u+es, pth, lfts (inc alp if vit d def), renal uss, xray (brown tumours)
- Treatment of hyperparathyroidism: surgery if >2.85, calcimimetics (cinacalcet), iv fluids 1L nacl over 4 hrs, bisphosphonates takes 7 days to work (calcitonin is quicker)
- Complications: dehydration + renal impairment
Hypocalcaemia:
- Definition
- Causes (3)
- Symptoms (4)
- Signs (2)
- Management
- What is pseudohypoparathyroidism
Hypocalcaemia:
- Definition: <1.9
- Causes (3): post parathyroidectomy, vit d deficiency/ckd, hypomagnesia, acute pancreatitis
- Symptoms (4): laryngospasm, perioral parasthesia, muscle cramps + tetany, seizures, carpal spasm, depression
- Signs (2): prolonged qt, + chvosteks (tapping over parotids = facial muscle twitching), trousseaus sign (carpal spasm if brachial art occluded during bp reading)
- Management: vit d cholecalciferol, oral ca, iv ca gluconate 10ml 10% if tetany/spasm iv mg
- What is pseudohypoparathyroidism: PTH rec mutation causing hypocalc - short, round face, short 4/5th metacarpal
Causes of raised ALP
If ca also raised:
- bone mets
- hyperparathyroidism
If ca low:
- osteomalacia
- ckd
No ca change:
- cholestasis
- liver hepatitis/neoplasia
Hypomagnesia:
- causes
- symptoms
- mx
Hypomagnesia:
- causes: diuretics/ppis, tpn, diarrhoea, alc, hypokal, hypercalc
- symptoms: paraesthesia, tetany, seizures, arrhythmias, ecg similar to hypoka
- mx: if <0.4 or tet/seizures/arrhythmia then iv mg, if >0.4 then oral mg salts (diarrhoea!!)
