Phosphorus

Question 1

Importance of phosphorus

Answer 1

• Major anion in intracellular space
• Component of ATP (Adenosine triphosphate)
• Cell membranes - phospholipids

Question 2

What are the causes of Hyperphosphatemia?

Answer 2

• Increased phosphorus intake due to vitamin D overdose
• Phosphate enemas
• > IV administration of phosphate
• Renal failure = most common
• more common in acute renal failure
• Decrease in excretion of phosphate:
• Uroabdomen or urethral obstruction
• Hypoparathyroidism and Hyperthyroidism
• Phosphate to translocate extracellularly:
• Metabolic acidosis
• Release of phosphorus from damaged cells into ECF space:
• Tumor cell lysis
• Tissue trauma
• rhabdomyolysis
• thromboembolic disease
• hemolysis

Question 3

What are the clinical signs of hyperphosphatemia?

Answer 3

• Results in compensatory hypocalcemia and clinical signs may be related to low calcium (tetany)
• often the most serious complication
• Hypotension and diarrhoea
• Secondary hyperparathyroidism - speed the progression of renal disease
• Soft tissue mineralisation

Question 4

Treatment of hyperphosphatemia

Answer 4

*Treat underlying cause
*Limit phosphate intake (low protein diet)
*IVF with 0.9%NaCl will dilute phosphorus in ECF and enhance renal excretion
*Administration of glucose with or without insulin
:temporarily reduces serum phosphate concentration
*Administration of phosphate binders with meals
:decrease phosphate absorption from food
:Aluminium hydroxide
:Aluminium carbonate
:90-100mg/kg/day
:divided into 2-3 doses