Red flag to remember
Respiratory muscle weakness or respiratory failure - report and support ventilation immediately.
What is hypophosphatemia?
Phosphorus is essential for cellular energy (ATP), so deficiency impairs energy-dependent functions throughout the body. Phosphorus and calcium have an inverse relationship, so signs of hypophosphatemia overlap with high calcium states.
Key points to remember
- Phosphorus and calcium are inversely related; as phosphorus falls, calcium tends to rise.
- Low phosphorus impairs ATP production, causing muscle weakness, including weakness of respiratory muscles.
- Neurologic signs include irritability, confusion, paresthesias, and seizures in severe deficiency.
- Hematologic effects include impaired oxygen delivery and increased risk of bleeding and infection.
- Bone pain and demineralization occur with chronic deficiency.
- Refeeding syndrome in malnourished clients can cause an abrupt, dangerous drop in phosphorus.
Common causes
- Refeeding syndrome
- Alcoholism, DKA, antacids
- Inverse to Ca (↑Ca = ↓Phos)
Signs & symptoms
- Muscle weakness, ↓ strength
- Confusion, irritability
- Bone pain, rhabdomyolysis
Nursing priorities
- Identify and correct the cause, and advance nutrition slowly in malnourished clients to prevent refeeding syndrome.
- Administer oral or IV phosphorus replacement as ordered, infusing IV phosphate slowly with monitoring.
- Monitor respiratory and muscle strength, since respiratory muscle weakness can compromise ventilation.
- Monitor serum phosphorus and calcium together during replacement.
- Encourage phosphorus-rich foods such as dairy, meat, fish, poultry, and whole grains.
Labs & values
Serum phosphorus normal3.0-4.5 mg/dL; hypophosphatemia is less than 3.0 mg/dL
Monitor calcium (normal9.0-10.5 mg/dL), which often rises as phosphorus falls
Patient teaching
- Eat phosphorus-rich foods such as dairy, meat, fish, poultry, nuts, and whole grains.
- Avoid overuse of aluminum or calcium-based antacids that bind phosphate.
- Report muscle weakness, numbness, tingling, or confusion.
Red flags: report now
- Respiratory muscle weakness or respiratory failure - report and support ventilation immediately.
- Seizures or acute confusion - notify provider and protect the client.
- Watch malnourished clients closely when feeding is started, since refeeding can cause a sudden severe drop.
References
Clinical references for this topic
Study Hypophosphatemia in the app4,000+ NCLEX questions with a rationale on every answer, NGN case studies and timed mock exams.See how CinnaRN works
Start free Want more Physiological Adaptation questions?We'll email you a free set on Hypophosphatemia. No account needed.
Was this helpful?