What is the most common cause of hypophosphatemia in hospitalized patients?

From the Guidelines

The most common cause of hypophosphatemia in hospitalized patients is glucose overload (option c). When patients receive high glucose loads, especially through intravenous feeding or refeeding after malnutrition, insulin is released which drives phosphate into cells along with glucose. This intracellular shift reduces serum phosphate levels, resulting in hypophosphatemia. This phenomenon is particularly common during total parenteral nutrition (TPN) administration or when refeeding malnourished patients. The body uses phosphate to metabolize glucose, and increased carbohydrate metabolism depletes serum phosphate stores. While renal failure typically causes hyperphosphatemia rather than hypophosphatemia, and both sepsis and diarrhea can cause hypophosphatemia, they are not as common as glucose-related causes in the hospital setting, as supported by the ESPEN guideline on clinical nutrition in hospitalized patients with acute or chronic kidney disease 1.

According to the most recent study, the initiation of kidney replacement therapy (KRT) is also a major risk factor for the development of hypophosphatemia 1. However, the use of dialysis solutions containing potassium, phosphate, and magnesium can help prevent electrolyte disorders during KRT 1. Clinicians should monitor phosphate levels closely when administering high glucose loads and consider phosphate supplementation when necessary to prevent complications like muscle weakness, respiratory failure, and cardiac dysfunction. The prevalence of hypophosphatemia in ICU patients can be as high as 60-80% 1, highlighting the importance of careful monitoring and management of phosphate levels in hospitalized patients.

Some key points to consider in the management of hypophosphatemia in hospitalized patients include:

• Monitoring phosphate levels closely in patients receiving high glucose loads or undergoing KRT
• Using dialysis solutions containing potassium, phosphate, and magnesium to prevent electrolyte disorders during KRT
• Considering phosphate supplementation when necessary to prevent complications
• Being aware of the high prevalence of hypophosphatemia in ICU patients and taking steps to prevent and manage it.

From the Research

Causes of Hypophosphatemia

• The most common causes of hypophosphatemia in hospitalized patients include:
  • Sepsis, as implicated in 26% of patients in one study 2
  • Glucose overload, which can occur due to intravenous administration of glucose, as seen in several studies 3, 4
  • Diarrhea, although not directly mentioned as a common cause in the provided studies
  • Renal failure, which can contribute to hypophosphatemia, but is not identified as the most common cause in the provided studies
• Other causes of hypophosphatemia mentioned in the studies include:
  • Refeeding syndrome 2, 4
  • Neoplastic disease 2
  • Medications such as diuretics, antacids, and steroids 4
  • Gram-negative septicemia 4
  • Surgery and postoperative fasting with intravenous glucose administration 4
  • Alcoholism and respiratory alkalosis 3

Prevalence of Hypophosphatemia

• Hypophosphatemia occurs in about 25% of patients admitted to the intensive care unit 5
• Severe hypophosphatemia (serum phosphorus less than or equal to 0.48 mmol/L) was found in 120 patients admitted to a major university hospital over a period of 16 months 4
• The mortality rate for patients with severe hypophosphatemia can be as high as 30% 2, 4