Hypophosphatemia

Hypophosphatemia is defined as a serum phosphate of < 2.5 mg/dL. It is more common in patients with alcohol use disorder and in critically unwell patients, who have high phosphate demands. Particularly in mild deficiency, symptoms can be nonspecific or absent entirely. However, severe hypophosphatemia can cause serious complications such as seizures, respiratory failure, and arrhythmias. Treatment may be oral or intravenous, depending on the severity of the deficiency, and should occur in conjunction with investigation of underlying causes. Supplementation regimens are covered in electrolyte repletion.

• Serum phosphate of < 2.5 mg/dL ^[1]
• Severe hypophosphatemia occurs at < 1 mg/dL. ^[1]

Although mild hypophosphatemia rarely causes symptoms, moderate to severe hypophosphatemia is associated with various cardiac, musculoskeletal, neurological, and hematological abnormalities. ^[3][4]

• Cardiac: arrhythmias
• Musculoskeletal
  • Generalized muscle weakness
  • Respiratory muscle dysfunction
  • Muscle pain
  • Osteomalacia
• Neurological
  • Fatigue
  • Dysarthria
  • Paresthesia
  • Altered mental state
  • Seizures
• Hematological
  • Signs of anemia, hemolysis, and thrombocytopenia
  • Impaired immunity

• Identify and treat the underlying cause (see etiology of hypophosphatemia).
• Consider discontinuation or dose reduction of any contributing medications.
• Phosphate supplementation (see repletion regimens for hypophosphatemia)

• Arrhythmias
• Seizures
• Respiratory failure

We list the most important complications. The selection is not exhaustive.