Order of draw- Cultures
- Clotting
- Chemistry (no additives)
- EDTA
- Can give falsely low Ca, Mg
- Also falsely low Alk-Phos, because it's an Mg-dept.reaction
- Fluoride-oxylate
Sodium limits - Phone for help
- Less than 125 mM
- More than 150 mM
- Life-threatening
- Less than 115 mM
- More than 160 mM
- NB hypernatraemia can be just as dangerous as hyponatraemia
- 40-50% mortality / 7X mortality increase
- Although not corrected for co-morbidities
Excreting products of metabolism - Require minimum 600 ml of urine to enable excretion, in a healthy adult
- Can be up to 1200 ml if sick
- Calculate how much sodium your patient has had!
- Antibiotics + fluids contribute LOADS of sodium
- May require up to 4 litres of urine per day to excrete
- HONK => Need extra water for excretion
- Make sure you give enough water, or 5% dextrose
- Even if they're diabetic, give dextrose (not significant in terms of blood glucose)
Causes of polyuria - Glucose
- Hypercalcaemia
- Hypokalaemia
- Diabetes insipidus
Hyponatraemia - UTI can => Tubule dysfunction => Hyponatraemia
- Drugs
- Schizophrenia => Polydipsia ?
- Some anaesthetics => ADH production
- Glycine buffer
- Used for irrigation in prostate, bladder, uterus surgery
- As it doesn't conduct as well as saline?
- Can get into blood => Hyponatraemia
- Pseudohyponatraemia
- Volume displacement causes raised blood volume and so apparently low sodium
- But the [Na] in the aqueous phase is actually normal
Hepatorenal syndrome
Notes - Renal failure => Hypocalcaemia
- Failure of vitamin D hydroxylation
- => High PTH
- => Renal bone disease
- Plasma sample
- Lithium heparin
- Orange / Green tube
- Doesn't clot => No risk of potassium release from platelets
- Be very wary of using half- or twice- normal saline
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