Specimen Name Result Units Range
Plasma Sodium 140 mmol/L (135-145)
Potassium 3.3 mmol/L (3.5-5.5)
Chloride 96 mmol/L (100-109)
Bicarbonate 27 mmol/L (22-32)
Anion Gap 20 mmol/L (7-17)
Urea 2.5 mmol/L (2.7-7.2)
Creatinine 80 μmol/L (60-110)
Phosphate 1.91 mmol/L (0.80-1.45)
Magnesium 0.50 mmol/L (0.70-0.95)
Total Calcium 1.66 mmol/L (2.10-2.55)
Albumin 37 g/L (34-48)
ALP 180 U/L (30-110)

7yo child with seizures.

What is the Ca++ disorder?
Hypomagnesaemic Hypocalcaemia (& hypokalaemia)

Very low Mg++ →

  • ↓PTH
  • ↑bone exchange : Ca++↔Mg++
  • bone resistance to PTH

 

Hypomagnesaemia Aetiology:

  1. factitious - haemodilution, severe hypoalbuminaemia
  2. common - GIT losses, diuretics, renal failure
  3. acute
    • β-adrenergic agonists - catecholamines
    • diarrhoea, vomiting, SI fistulae
    • acute pancreatitis
  4. chronic
    • nutritional - NBM, malnutrition, TPN, infants + cows milk
    • cirrhosis & chronic alcoholism
    • GIT - diarrhoea, malabsorption, SI fistulae, NG aspiration
    • drugs:
      • diuretics
      • gentamicin/aminoglycosides
      • cisplatinum
    • endocrine:
      • hyperthyroidism, hyperparathyroidism
      • hyperaldosteronism, DM
      • osteitis fibrosa cystica
    • renal - chronic diseases, haemodialysis / haemoperfusion
    • SIADH
    • familial hypomagnesaemia

NB:

  • ∴ Mg++ deficiency frequently → hypokalaemia and hypocalcaemia
  • Mg++ frequently follows K+ in the ICF environment
  • when deficits of Mg++ and K+ coexist, Mg++ repletion is often required to correct the later
  • the interaction of the two ions is thought to be mediated by the effects of adrenal steroids on renal excretion