Hypophosphatemia-factors associated with its development and 90-day mortality effect: a prospective observational...

Several factors are associated with hypophosphatemia. There is a paucity of data regarding the effects of restrictive energy delivery and phosphate renal handling with hypophosphatemia in the critically ill patient.

This is a single-center observational study. Patients were included if they were admitted ventilated and their ICU stay was at least 48 h. Baseline characteristics were recorded upon admission; other variables were collected daily during the first five admission days: SOFA1 score, serum phosphate, energy delivery, phosphate delivery and fluid balance. A 6-h urine collection for phosphate and creatinine was performed daily. Creatinine clearance (CrCl_6hr), tubular reabsorption of phosphate (TRP), and tubular maximal reabsorption rate of phosphate adjusted to the glomerular filtration rate (TmP/GFR) were calculated. Mortality follow up time was 90 days. A comparison was made between patients who developed hypophosphatemia (serum phosphate < 2.5 mg/dl), and those who did not. Univariate and multivariate regressions for hypophosphatemia and for 90-day mortality were performed.

One hundred eighty-one patients were included in the analysis. One hundred and nine (60.22%) developed hypophosphatemia. They were younger, had lower APACHE2 score, and were admitted more frequently due to trauma. No association of energy delivery with hypophosphatemia was found. In a multivariate analysis only log of CrCl_6hr and TmP/GFR were associated with hypophosphatemia. Hypophosphatemia was associated with 90-d mortality in univariate analysis, but not in multivariate analysis.

Creatinine clearance based on a 6-h urine collection and TmP/GFR were associated with hypophosphatemia, whereas energy delivery was not. Age and APACHE2 were associated with 90-d mortality, but hypophosphatemia was not.