Electrolytes Flashcards
List causes of hyponatraemia
Dry (hypovolaemia)
Body loses Na and water, often in combination with an ↑ in H2O intake.
- R: Diuretics, osmotics, CRF, RTA, Nephritis
- E: ↓ Aldo….What does aldosterone do?
- G: D + V, GIT Fistula, NGT losses, pancreatitis (with 3rd space losses)
- S: Sweat +++, Burns
Wet (hypervolaemia)
There is an excess of total body water
- R: ARF, Nephrotic syndrome
- E: ↑ Aldo (eg. CCF)
- G: Cirrhosis (low albumin/protein)
- S: I.V. Fluids (too much hypotonic stuff eg 5% Dextrose)
Euvolaemic (Normal)
- R: Drugs (lots of them….like NSAIDS, TCA’s, Carbamazepine)
- E: ↓ Thyroid
- G: H2O Intoxication
- S: S.I.A.D.H. ( Nothing to do with skin this time)
What are some causes of SIADH?
- small cel cancer
- bronchogenic carcinoma
- leukaemia
- pancreatic adenocarcinoma
- iatrogenic
- post op state
- pain/nausea
- airway
- pneumonia
- lung abscess
- TB
- asthma
- COPD
- drugs
- TCAs, SSRIs
- oxytocin
- carbamazapine
- nicotine
- heat injury
- stroke
- encephalopathy
- subarach
List some causes of hypernatraemia
Due to H2O loss:
- R: Intrinsic disease (amyloid, sarcoid, myeloma) ATN, CRF Osmotic agents (eg. High glucose, mannitol) Diuretics
- E: ↑Ca2+ D.I. (a complex issue we’ll get to later)
- G: D+V, Fistula, NGT, Cathartics
- S: Sweat, Burns
Due to excess Na+ load:
- R: Dialysis
- E: ↑ Aldo (eg. Cushing’s syndrome)
- G: I.V. Fluids, NGT feeds
Clinical manifestations of hyponatraemia
- CNS:
- Increased water into brain so…..
- Confusion, apathy, agitation
- Headache
- Focal weakness, hemiparesis, ataxia
- Fit, coma
- CVS:
- Depends on volume state
- Potentiates shock state…..WHY? Vasoconstriction
- MSkel: Cramps, weakness
- You should usually only raise the sodium by ½ mmol/hr.
Clinical manifestations of hypernatraemia
- Often Pt is O.K. until Na+ > 160
- CNS: Due to the brain shrinking so….
- Lethargy, confusion, apathy
- Fits, coma
- Vascular rupture due to vessel stretch (ICH, SAH, CVA) (Note: Mortality with CNS changes due to high sodium is 50%)
- CVS:
- Hypotension
- Tachycardia
- MSkel: weakness, cramps
You should usually only lower the sodium by ½ mmol/hr
How do you calculated how the bag of fluid you are about to give a patient will change their sodium level?
Infusate [Na+] - Serum [Na+]
TBW + 1
Total body water (TBW) is based on a percentage of body
Males / Kids = 60%
Old males / Females = 50%
Old females = 45%
How much Sodium is in a bag of:
- Normal saline?
- Hartmans?
- 5% Dextrose?
- Hypertonic Saline?
- N/2?
- Normal saline? 154
- Hartmans? 130
- 5% Dextrose? 0
- Hypertonic Saline? 514
- N/2? 78
List causes of hyperkalaemia
- 1.Pseudo…..not high in Pt, just in the sample
- 2.Shift….Whole body levels remain the same but K+ moves out of cells
- 3.Load…too much going in and
- 4.Loss….not enough going out
- Pseudo:
- Haemolysed blood specimen
- Sample from arm with iv line running
- Very high WCC
- Shift :
- Acidosis
- Exercise
- Not enough insulin
- Digoxin toxicity
- Hyperkalemic periodic paralysis
- Load:
- Too much from external K+ supplements
- Blood transfusion
- Too much from inside
- Rhabdomyolysis
- Red cell haemolysis
- Suxamethonium induced
- Loss:
- Renal failure
- K+ sparing diuretics
- ↓ Aldosterone
Clinical manifestations of hyperkalaemia
- CNS: Weakness, ↓ Reflexes, Paresthesia
- CVS: Arrhythmias (PVC’s, VF, CHB, Asystole)
- GIT: Nausea, D+V, Colicky Pain
Treatment of hyperkalaemia
Treatment Onset Lasts Dose Mechanism
- Ca Gluconate - Antagonist
- onset 1m, lasts 2hrs
- Bicarbonate - Antag/Redis.
- onset 5m, lasts 2hrs
- I.V. Insulin/Glucose - Redistribution
- onset 30m, lasts 6hrs
- Frusemide - diuresis
- onset 1hr, lasts 6hrs
- Polystyrene Sulphate - Cation exchange
- onset 1hr
Can also use salbutamol
Causes of hypokalaemia
- Shift….Whole body levels remain the same but K+ moves out of cells
- Loss …too much going out (back to the “REGS” list)
- Drugs…..and
- Other
- Shift:
- Alkalosis Insulin
- Catecholamine infusion
- Loss:
- Renal
- Liquorice
- RTA
- Endo
- ↑ Aldo -1˚
- -2˚ due to CCF, Cirrhosis, Ascites.
- Low magnesium
- Renal
- Drugs:
- Diuretics
- Penicillin
- Lithium
- Anti-parkinsonian drugs
- Other:
- Bartter’s syndrome
- Acute Myeloid Leukaemia
Clinical manifestations of hypokalaemia
CNS: Weakness, ↓ Reflexes, Paresthesia
CVS: Tachycardia,
GIT: Nausea, D+V, Colicky Pain
Treatment for hypokalaemia?
Slow K
KMag
Chlorvescent Kayciel
I.V.: Replace at a maximum of 20 mmol/hr via a peripheral line Or 40 mmol/hr via a central line
And, obviously, correct the underlying cause.
Causes of hypercalcaemia
- primary hyperparathyroidism
- malignant disease
- venous stasis
- thiazided diuretics
- Addison’s disease
- increased Vit D/ thyroid
Clinical manifestations of hypercalcaemia
- Bones: Bone pain, osteoporosis
- Stones: Renal and gall stones
- Groans: Pancreatitis, peptic ulcers and constipation
- Moans: Confusion and psychos
Cardiac problems can arise such as:
- Brady arrhythmias
- Complete heart block
- Hypotension due to ↓ myocardial contractility
Other general symptoms include: Lethargy, nausea and vomiting, weight loss, thirst.
ECG changes for hypercalcaemia
- short QT
- J waves
ECG changes for hypocalcaemia
- long QT
ECG changes for hyperkalaemia
- peaked T waves
- ST elevation
- flat P waves
- short QT
- Widening of QRS
- can progress to VF
ECG changes for hypokalaemia
- prominent U waves
- flat T waves/inverted
- ST depression
- prolonged PR
- heart block (1,2,3)
