Electrolyte disturbance Flashcards
What are some clinical features of hyponatraemia?
Nausea and vomiting Headache Confusion Lethargy Fatigue Anorexia Irritability Muscle weakness Cramps Seizures Drowsiness Coma
A lot of the symptoms of hyponatraemia are cerebral in nature, why is this?
When there is low sodium in the blood the osmotic pressure changes and water starts to move into tissues. Due to the fixed pressures in the skull this causes compression and symptoms to occur much sooner
CEREBRAL OEDEMA
What are some common causes of hyponatraemia?
IATROGENIC - Inappropriate fluid replacement Burns Excessive exercise w/o replacing electrolytes Diarrhoea Polydipsia Taking ecstasy SIADH Nephrotic syndrome Renal impairment Hepatic cirrhosis
If someone is symptomatically hyponatraemic what investigations should you do?
FBC
U&E
CT head and neck
ECG
How should hyponatraemia be treated?
If mild then just fluid restriction
If neurological symptoms start to occur people will need SODIUM BOLUS - 200mL 2.7% NaCl over 30 mins
IF Na <120mmHg THIS IS ASSOCIATED WITH BRAIN HERNIATION
Why is it important to know whether the hyponatraemia is acute or chronic?
If hyponatraemia is CHRONIC then you shouldn’t replace it too quickly - can lead to CENTRAL PONTINE MYELINOLYSIS (particularly in patients with low k+ or alcoholics)
Do NOT treat faster than 10mmol/L over 24h
What are the main symptoms of hypernatraemia and why do they occur?
Confusions
Muscle twitching
Seizures
Comas
Occurs because as Na cones increase osmotic pressure is such that water moves out of brain tissue and the brain shrinks?
What are some common causes of hypernatraemia and who does it commonly occur in?
Poor fluid intake - leads to increased concentration in the blood. Happens in the ELDERLY
Excessive water loss e.g. due to glycosuria
Diarrhoea and vomiting
Hypetonic fluid replacement
Cushing’s syndrome
Diuretics
What are some common complications of hypernatraemia?
Seizures, extra-dural and sub-dural haemorrhage, ischaemic strokes and dural sinus thrombosis
What investigations should be done if someone has hypernatraemia?
FBC, U&E and any investigations relevant to their symptoms (possibly CT head or MRI)
How should hypernatraemia be corrected?
SLOWLY. No more than a 1mmol/L drop every hour
Use a 0.9%NaCL fluid to correct hypovolaemia and when the patient is euvolaemic use 0.45% saline
How do we classify hyperkalaemia?
MILD (5.5-6.0mmol.L)
MODERATE (6.1 - 6.9mmol/L)
SEVERE (>7.0mmol/L)
What are some symptoms of hyperkalaemia?
Muscle weakness/cramps, parasthesia, hypotonia, focal neurological deficits
What are some common causes of hyperkalaemia?
IATROGENIC - giving too much K+ in fluids (although quite often the sample is wrong - if someone is having an infusion into that arm do not take bloods from the same side)
AKI
K sparing diuretics (spironolactone and amilioride)
Cell injury (crush injuries, rhabdomyolysis, burns, tumour cell necrosis)
ACIDOSIS FROM ANY CAUSE (causes IC-EC K shift)
Suxamethonium and B-blockers
Hypoaldosteronism (Addison’s)
What are some relevant investigations if you suspect someone is hyperkalaemic?
FBC, U&E
ECG
Blood glucose
How should hyperkalaemia be managed?
URGENT TREATMENT REQUIRED if K >6.5mmol/L
DO AN ECG - if there are no ECG changes then repeat blood test from a different site (measure using gas machine for instant result)
If hyperkalaemia persists or there are ECG changes start treatment
10mL of 10% CaCl slowly IV (over 5mins) - this does not affect K but will ANTAGONISE the cardiac myocyte reducing the chance of arrhythmias
10U short acting human soluble insulin with 50mL of 50% glucose IV
5mg Nebulised salbutamol
Correct volume deficiencies
Correct acidosis
Contact renal team
What are some signs of hypocalcaemia?
Neuromuscular excitability
Numbness around the mouth and peripheral limb parasthesia
Hyper-reflexia
Carpopedal spasm
Focal or generalise seizures
Hypotension and bradycardia
Tetanic contractions
Chvostek’s sign - tapping the facial nerve just behind the ear leads to facial spasm
Trousseau’s sign - inflate BP cuff to just above SysBP and mild ischaemia, hyperexcitability and carpospasm will be seen
What investigations should be done in hypocalcaemia?
Plasma Ca, Po4 and albumin Plasma Mg U&E ECG Plasma PTH (parathyroid hormone)
How should hypocalcaemia be managed?
Management based around helping symptoms rather than correcting calcium
10mls 10% calcium gluconate for frank tetany - slow IV over 10mins
Oral calcium and vitamin D
What are some causes of hypocalcaemia?
Vitamin D deficient Hypoparathyroidism Chronic renal failure Acute pancreatitis Hyperphosphataemia Magnesium deficiency Sepsis burns
What are some causes of hypercalcaemia?
Hyperparathyroidism Hyperthyroidism Sarcoidosis Immobilisation (Paget's disease) Pheochromocytoma Adrenal failure Rhabdomyolysis Drugs - Lithium, thiazide like diuretics, theophylline toxicity
What are some presenting features of hypercalcaemia?
Depression, weakness, tiredness, fatigue
Constipation, anorexia, N&V and weight loss
Renal calculi, polydipsia and polyuria
Anxiety, depression, coma or obtundation
Hypertension or cardiac dysarrythmias
When should urgent treatment be given in hypercalcaemia?
If Ca is >3.5mmol/L
IF there is clouding of the consciousness or confusion
If there is hypotension
If there is severe dehydrations
How should hypercalcaemia be managed?
REHYDRATE with 0.9% NaCl
If the patient does not pass urine for 4h then put in a catheter
DIURETICS - once you are confident the patient is rehydrated then give them furosemide
Monitor K and Mg levels respectively
BISPHOSPONATES can be considered - they inhibit osteoclast activity therefore reducing further increase in Ca
