Phosphorus

Hypophosphatemia

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Hypophosphatemia, Low Serum Phosphorus

  • Causes
  1. Starvation
  2. Diabetic Ketoacidosis
  3. Total Parenteral Nutrition (TPN)
  4. Insulin
  5. Nasogastric Suction (NG Suction)
  6. Diuretics
  7. Vomiting
  8. Vitamin D Deficiency
  9. Hypoparathyroid
  10. Pseudohypoparathyroidism
  11. Medications
    1. Corticosteroids
    2. Aluminum Hydroxide Antacids
  12. Gram Negative Sepsis
  • Evaluation
  1. Check Urinary Phosphate excretion (Urine Phosphorus)
  2. Low Urine Phosphorus: under 100 mg/d (FePO4 under 10%)
    1. Internal Redistribution
      1. Glucose administration
      2. Alkalosis
      3. DKA recovery
    2. Gastrointestinal Losses
      1. Malabsorption
      2. Vomiting
      3. Diarrhea
      4. Aluminum or MagnesiumAntacids
  3. High Urine Phosphorus: over 100mg/d (FePO4 over 20%)
    1. Check for wasting in urine of other Electrolytes
      1. Glucose
      2. Amino Acid
      3. Uric Acid
      4. Bicarbonate
    2. Electrolyte Wasting present
      1. Fanconi's Syndrome
        1. Idiopathic
        2. Sporadic
        3. Familial
      2. Cystinosis
      3. Amyloidosis
      4. Multiple Myeloma
      5. Wilson's Disease
      6. Nephrotic Syndrome
      7. Cadmium toxicity
      8. Acute Lead Toxicity
    3. Electrolyte Wasting absent
      1. Increased Serum Calcium
        1. Primary or ectopic Hyperparathyroidism
      2. Normal or Low Serum Calcium
        1. Secondary Hyperparathyroidism
        2. Androgen or Estrogen treatment
        3. Thiazide Diuretics
        4. Vitamin D resistant Rickets
        5. Post Acute Tubular Necrosis
        6. Post-transplant
  • Management
  1. See Phosphorus Replacement