From the Guidelines
Hypophosphatemia is caused by several mechanisms, including decreased intestinal absorption, increased urinary excretion, or intracellular shifting of phosphate, with common causes including malnutrition, vitamin D deficiency, and certain medications, as well as genetic disorders like X-linked hypophosphatemic rickets, as noted in a 2019 study published in Nature Reviews Nephrology 1.
Causes of Hypophosphatemia
- Decreased intestinal absorption
- Increased urinary excretion
- Intracellular shifting of phosphate
- Malnutrition
- Vitamin D deficiency
- Chronic alcoholism
- Refeeding syndrome
- Certain medications, such as antacids containing aluminum or magnesium, diuretics, and certain antibiotics
- Hyperparathyroidism
- Diabetic ketoacidosis
- Respiratory alkalosis
- Genetic disorders, including X-linked hypophosphatemic rickets and tumor-induced osteomalacia
Treatment of Hypophosphatemia
- Phosphate supplementation, either orally or intravenously in severe cases
- Oral phosphate supplements typically contain sodium or potassium phosphate
- Severe cases may require IV phosphate at 0.08-0.16 mmol/kg over 4-6 hours
- Addressing the underlying cause is essential for long-term management of phosphate levels, as emphasized in a 2021 study published in Clinical Nutrition 1.
Important Considerations
- Monitoring of electrolytes, including phosphate, potassium, and magnesium, is crucial in patients with acute or chronic kidney disease, as highlighted in a 2021 guideline published in Clinical Nutrition 1.
- Hypophosphatemia can have significant clinical implications, including worsening respiratory failure, increased risk of prolonged weaning from mechanical ventilation, and cardiac arrhythmias, as noted in a 2019 study published in Nature Reviews Nephrology 1.
From the Research
Causes of Hypophosphatemia
- Inadequate intake, decreased intestinal absorption, excessive urinary excretion, or a shift of phosphate from the extracellular to the intracellular compartments can cause hypophosphatemia 2
- Renal phosphate wasting can result from genetic or acquired renal disorders, such as vitamin D deficiency hyperparathyroidism, oncogenic osteomalecia, and Fanconi syndrome 2
- Genetic disorders of renal hypophosphatemic disorders generally manifest in infancy and are usually transmitted as an X-linked hypophosphatemic rickets 2
- Certain medications, such as diuretics, bisphosphonates, antibiotics, insulin, and antacids, can also cause hypophosphatemia 3
- Insulin treatment for diabetic ketoacidosis can result in hypophosphatemia, even in patients with mild hypophosphatemia 4, 5
Factors Associated with Hypophosphatemia
- Higher glycohemoglobin levels are associated with greater odds of hypophosphatemia 5
- Older age, male sex, longer duration of type 1 diabetes mellitus, and initial normal conscious state are associated with lower odds of developing hypophosphatemia 5
- Hypophosphatemia is associated with longer hospital length of stay 5
Underlying Mechanisms
- Phosphate metabolism is an evolving area of basic and clinical research, and disturbances of phosphate homeostasis can have significant clinical consequences 6
- The clinical evaluation of hypophosphatemia should initially focus on the assessment of pathophysiological mechanisms leading to low serum phosphate concentrations 6