Electrolyte Disturbances - Hyponatraemia
Electrolyte Disturbances - Hyponatraemia
KCL 1g = 13.3 mmol K+
KCL SOLUTION=250mg/5ml
KCL 15% 1ml = 2mmol K+
Think about diagnosis in children with:
- Gastro ±seizures
- Oedema
- Polyuria/Polydipsia
- Diabetes Mellitus
- TBM
- Congenital adrenal hyperplasia
- Hypothyroidism
- Water overload
- What replacement fluid has child been getting?
- Water retention
- SIADH
- Sodium loss (skin/renal/GIT)
- False secondary to hyperglycaemia / hyperlipidaemia
Management:
Normal or Overhydration:
- Cut back on IV fluids restrict to 60ml/kg.
- Consider changing to 0.9% N/S with dextrose as maintenance.
- Check serum and urine osmolality and urine electrolytes.
Dehydrated:
- Check glucose to exclude hyperglycaemia
- Consider stopping diuretics
- Check serum and urine osmolality and urine electrolytes only if not D & V
- Use 1/2 N/S as base for rehydration add dextrose and K+ as required and rehydrate slowly over 24-48 hrs
Use 5% sodium chloride for life threatening hyponatremia (<125mmol/l) in discussion with consultant.
Calculating Sodium Correction:
Sodium deficit (mmol) = (130- Pt Na+) X 0.6 X Wt(kg)
Volume of 5% NaCl = mmol deficit / 0.855
5% sodium chloride = 855mmol/l Na+
0,9% sodium chloride = 154mmol/l Na+
5% Sodium Chloride (855mmol/l Na+) correction
Only to correct severe hyponatremia Na+< 125mmol/l
- Stop once corrected to >130mmol/l
- Go slow, aim for 0.5 - 1mmol/l/hr correction
- Recheck the Na+ regularly 4-6 hrs
- Na+ deficit = (130-serum Na+) x 0.6 = mmol Na+
- No of mls to give = Na deficit / 0.855 = mls of 5%NaCl
- Run the solution over (2 x deficit) hrs
Therefore ml 5% NaCl needed to correct: [(130-Na) X 0.6X Wt] ÷ 0.855
Eg. 12kg child with hyponatremia Na 119mmol/l and BE -12
Deficit: (130 – 119) X 0.6 X 12 = 79mmol
Volume of 5% NaCl: 79/0.855 =92 ml
Rate of 5% NaCl: 92 ml/24hours = 3,8ml/hr 5% NaCl as side infusion