Module 8 Part 3 Phosphorus

Hypophosphatemia Major Causes

Malnutrition, hyperparathyroidism (increased urinary loss), burns, calcium/magnesium-based antacids, refeeding syndrome

Hypophosphatemia CNS Signs

Irritability, confusion, seizures

Hypophosphatemia Cardiac Signs

Decreased contractility and cardiac output, slow peripheral pulses

Hypophosphatemia Musculoskeletal/Bone Signs

Rhabdomyolysis; decreased bone density, altered bone shape; risk of pathological fracture

Hypophosphatemia Management

Discontinue contributing medications; oral phosphorus + Vitamin D; IV phosphorus if level

Hyperphosphatemia Major Causes

Increased intake, CKD (decreased excretion), tumor lysis syndrome, hypoparathyroidism

Hyperphosphatemia CNS Signs

Anxiety, irritability, seizures

Hyperphosphatemia Cardiac Signs

Bradycardia, hypotension, diminished pulses; EKG: prolonged ST and QT intervals

Hyperphosphatemia Musculoskeletal Signs

Hyperactive DTRs, skeletal muscle twitching/cramping, paresthesias; positive Trousseau's and Chvostek's signs

Hyperphosphatemia GI Signs

Increased GI motility, hyperactive bowel sounds, cramping, diarrhea

Hyperphosphatemia Management

Manage co-occurring hypocalcemia; phosphate-binding medications (PhosLo/calcium acetate, Renvela/sevelamer); avoid phosphate-containing laxatives/enemas; limit phosphate-rich foods

Hyperphosphatemia → Hypocalcemia Link

High phosphorus binds calcium → lowers serum calcium → causes hypocalcemia signs (tetany, Trousseau's, Chvostek's, prolonged QT)

Hypo vs Hyperphosphatemia Cardiac

Hypophosphatemia = decreased contractility, slow pulses; Hyperphosphatemia = bradycardia, hypotension, prolonged ST/QT