Mild hypophosphatemia is defined as a serum phosphorus level of 0.65-0.80 mmol/L. For subjects with mild hypophosphatemia, the phosphorus supplementation dose is 0.306 mmol/(kg·d) based on the subject's actual body weight. During treatment, venous blood is drawn daily between 5:00 and 6:00 AM to measure serum phosphorus levels and evaluate the effectiveness of supplementation. The investigator determines the severity of hypophosphatemia based on the day's serum phosphorus level and administers the corresponding phosphorus supplementation dose for mild, moderate, or severe cases.

Moderate hypophosphatemia is defined as a serum phosphorus level of 0.32-0.64 mmol/L. For subjects with moderate hypophosphatemia, the phosphorus supplementation dose is 0.612 mmol/(kg·d) based on the subject's actual body weight. During treatment, venous blood is drawn daily between 5:00 and 6:00 AM to measure serum phosphorus levels and evaluate the effectiveness of supplementation. The investigator determines the severity of hypophosphatemia based on the day's serum phosphorus level and administers the corresponding phosphorus supplementation dose for mild, moderate, or severe cases.

Severe hypophosphatemia is defined as a serum phosphate level <0.32 mmol/L. For subjects with severe hypophosphatemia, the phosphorus supplementation dose is 0.816 mmol/(kg·d) based on the subject's actual body weight. During treatment, venous blood is drawn daily between 5:00 and 6:00 AM to measure serum phosphorus levels and evaluate the effectiveness of supplementation. The investigator determines the severity of hypophosphatemia based on the day's serum phosphorus level and administers the corresponding phosphorus supplementation dose for mild, moderate, or severe cases.

After signing the informed consent form (ICF), eligible subjects were stratified based on the severity of hypophosphatemia during the screening period: mild hypophosphatemia (0.65-0.80 mmol/L), moderate hypophosphatemia (0.32-0.64 mmol/L), or severe hypophosphatemia (<0.32 mmol/L).

Following enrollment, subjects entered a treatment period of up to 14 days. All subjects received a differentiated phosphate supplementation strategy based on actual body weight: subjects with mild hypophosphatemia received 0.306 mmol/(kg·d); those with moderate hypophosphatemia received 0.612 mmol/(kg·d); and those with severe hypophosphatemia received 0.816 mmol/(kg·d). During the treatment period, venous blood was drawn daily between 5:00 and 6:00 AM to measure serum phosphorus levels and evaluate the efficacy of supplementation. Based on the daily serum phosphorus level, the investigator determined the severity of hypophosphatemia and administered the corresponding phosphate dose.

Among patients receiving enteral phosphate supplementation during the study period, the proportion achieving the target serum phosphate level (≥0.80 mmol/L). This proportion ranges from 0% to 100%, with a higher value indicating better treatment efficacy of enteral phosphate supplementation.

The magnitude of serum phosphorus elevation per 1 mmol of enteral phosphorus supplementation in patients during the study period. A greater magnitude of serum phosphorus elevation indicates better treatment efficacy of phosphorus supplementation.