Specimen Name Result Units Range
Plasma Sodium 143 mmol/L (135-145)
Potassium 2.7 mmol/L (3.5-5.5)
Chloride 98 mmol/L (100-109)
Bicarbonate 37 mmol/L (22-32)
Glucose 5.8 mmol/L (3.8-5.5)
Urea 6.6 mmol/L (2.7-7.2)
Creatinine 110 μmol/L (60-110)

47yo female with weakness & BP = 180/110mmHg.
Primary Hyperaldosteronism

Causes of hypertension and hypokalaemic alkalosis

  • essential hypertension & diuretic use
  • primary hyperaldosteronism
  • essential hypertension & 2° hyperaldosteronism
    • malignant hypertension
    • renovascular hypertension
    • drugs - steroids, oestrogen
    • renin-secreting tumour
  • Cushing's syndrome
  • congenital adrenal enzyme deficiencies
  • carbenoxolone
  • Liddle's syndrome - 'pseudohyperaldosteronism'

 

Conn's Syndrome

  • benign adenoma of the zona glomerulosa of the adrenal cortex
  • rarely due to bilateral hyperplasia or carcinoma
  1. hypertension - mild diastolic hypertension ± headaches
  2. hypokalaemia
    • often severe
    • weakness ± paralysis
    • polyuria 2° nephrogenic DI
    • ECG : U-waves, PVCs, arrhythmias
  3. metabolic alkalosis
  4. polyuria ∝ hypokalaemic nephrogenic DI ± polydipsia
  5. biochemistry
    • hypokalaemic metabolic alkalosis
    • hypernatraemia : often normal ± mild Na+ retention / nephrogenic DI
    • low plasma renin-activity
  6. oedema → classically absent
    • exhibit intrinsic renal "escape" from mineralocorticoid
    • may occur in longstanding cases 2° to CCF & azotaemia

 

Hypokalaemic Metabolic Alkalosis
Diuretics (esp. loop agents) - low Na+, Cl- / high urea
Mineralocorticoid excess - normal-high Na+, Cl- / normal urea
Vomiting / Gastric outlet obs. - very low Cl- / low-normal Na+ / high urea
Diarrhoea / laxatives - low Cl- / normal Na+ / high urea
Post massive transfusion - citrate metabolism & acidosis correction