From the Guidelines
The most common cause of hypophosphatemia in hospitalized patients is glucose overload (option c). When patients receive high glucose loads, either through intravenous glucose administration 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), refeeding syndrome, and treatment of diabetic ketoacidosis. The rapid cellular uptake of phosphate occurs without actual phosphate depletion in the body, but creates a measurable drop in serum levels. While sepsis, renal failure, and diarrhea can all affect phosphate levels, glucose-induced intracellular shifting is encountered most frequently in hospital settings, especially in critically ill patients or those receiving nutritional support after periods of starvation. According to the most recent study 1, electrolyte disorders are common among hospitalized patients, and hypophosphatemia has a high reported prevalence (60-80%) in the ICU. The initiation of KRT is a major risk factor for the development of hypophosphatemia, but glucose overload is still considered the most common cause.
Some key points to consider:
- Hypophosphatemia is associated with a global negative impact on patients’ outcome, including worsening respiratory failure and increased risk of prolonged weaning from mechanical ventilation, cardiac arrhythmias, and prolonged hospitalization 1.
- Phosphate balance is maintained through a complex interaction between phosphate uptake and phosphate excretion, and in hospitalized patients, the mechanisms regulating this interaction are frequently disrupted, leading to an increased risk for hypophosphatemia 1.
- The use of dialysis solutions containing potassium, phosphate, and magnesium can help prevent electrolyte disorders during KRT, including hypophosphatemia 1.
Overall, glucose overload is the most common cause of hypophosphatemia in hospitalized patients, and it is essential to monitor and manage phosphate levels closely in these patients to prevent complications and improve outcomes.
From the Research
Causes of Hypophosphatemia
- The most common causes of hypophosphatemia in hospitalized patients are:
- 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 45 cases in another study 3
- Diarrhea is not mentioned as a primary cause in the provided studies
- Renal failure is not explicitly mentioned as a primary cause in the provided studies, but it can be a contributing factor to hypophosphatemia
Prevalence of Hypophosphatemia
- Hypophosphatemia is common in hospitalized patients, with 2% of requests for serum phosphate determination resulting in levels ≤0.5 mmol/l in one study 2
- Severe hypophosphatemia is associated with a high mortality rate, with 30% of patients dying in one study 2 and 80.8% of patients with severe hypophosphatemia dying in another study 4
Patient Groups at Risk
- Patients in intensive care units (ICUs) are at high risk of developing hypophosphatemia, with 45% of patients with low phosphate levels occurring in an ICU setting in one study 2
- Patients with neoplastic diseases, possible refeeding syndrome, and septic patients are also at high risk of developing hypophosphatemia 2