K+

Potassium is controlled by the 

• kidneys (aldosterone)

• transcellular shift (insulin, catecholamine)

Hypokalemia

• Redistribution into cells - insulin, alkalosis, beta agonists

• Loss

  • • renal - diuretics, hyperaldosteronism, low Mg2+, RTA

    • GI - fistula, vomiting/diarrhoea

Hyperkalemia

• Decreased excretion - CKD, ACEi/ARB, Addison's, Spiranolactone

• Shift from cell - Acidosis, tumour lysis, scoline

Never give Calcium in digoxin toxicity

Potassium-Hydrogen Balance

• Controlled by Aldosterone, Insulin, pH, Catecholamines, and renal flow.

• Endocrine disorders that affect it: 

  • • Conn’s (Primary hyperaldosteronism): K⁺ ↓, metabolic alkalosis

    • Addison’s: K⁺ ↑, Na⁺ ↓, hypotension

    • Cushing’s: K⁺ ↓ (cortisol cross-reacts with mineralocorticoid receptors)

    • Hypoinsulinaemia (DKA): K⁺ ↑ in serum but total body K⁺ ↓

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