Most abundant element in body. Important element in ATP energy systems, intracellular signalling (cAMP) and the synthesis of nucleic acids. 80-85% is in bone. Normally renal excretion = gastrointestinal absorption
• decrease in plasma phosphate concentration – due intracellular shift (when carbohydrate metabolism is increased – eg IV glucose, insulin; also occurs in respiratory and metabolic alkalosis), increased excretion (eg hyperparathyroidism) or decreased absorption (eg starvation).
• weakness is most common symptom
• management – oral replacement
• increase in plasma phosphate concentration – occurs when load from absorption, exogenous administration and cellular release exceeds renal excretion and uptake by tissues – most often in association with acute or chronic renal disease.
• most commonly complain of muscle cramping may progress to tetany
• can have neuromuscular hyperexcitability and parathesia (especially distal extremities)