Hypophosphate

Question 1

What are the clinical features of low phosphate/ CONSEQUENCES

Answer 1

• Generally asymptotic if mild 
	• Can cause systemic features
		○ CNS and MSK: weakness, myalgia, myopathy, rhabdomyolysis lethargy, confusion, seizures, coma, hallucinations, somnolence, irritability
		○ Cardiorespiratory failure
		○ Arrythmias cardiomyopathy
		○ Rickets/osteomalacia if chronic 
Consequences
	• red blood cell haemolysis
	• white blood cell and platelet dysfunction
	• muscle weakness and rhabdomyolysis
central nervous system dysfunction

Question 2

What causes low phosphate

Answer 2

• Redistribution into cells: respiratory alkalosis, drug therapy insulin, catecholamines
  
  • Increased urinary excretion: metabolic or respiratory acidosis (e.g DKA), hyperparathyroidism
  • Decrease intestinal absorption e.g antacid abuse, vitamin D deficiency, chronic diarrhoea, Malabsorption
  • Acute liver failure
  • Renal tubular dysfunction
• Refeeding

Question 3

How do you investigate low phosphate

Answer 3

Check calcium, UE, Renal function

Question 4

How do you manage low phosphate

Answer 4

• Use local guidelines
• Typically oral replacement for a mild deficiency (e.g. phosphate Sandoz) & IV therapies if moderate or severe
• PO therapy risks diarrhoea
IV therapy via phosphate polyfusor has a large amount of potassium. Be careful of this contraindication in patients with hyperkalaemia

Question 5

When should you never give IV phosphate

Answer 5

Never give IV phosphate to a patient who is hypercalcaemic or oliguric