Rn. Dickerson et al., A comparison of renal phosphorus regulation in thermally injured and multiple trauma patients receiving specialized nutrition support, J PARENT EN, 25(3), 2001, pp. 152-159
To compare phosphorus intake and renal phosphorus regulation between therma
lly injured patients and multiple trauma patients, 40 consecutive criticall
y ill patients, 20 with thermal injury and 20 with multiple trauma, who req
uired enteral tube feeding were evaluated. Phosphorus intakes were recorded
for 14 days from the initiation of tube feeding which was started 1 to 3 d
ays postinjury. Serum for determination of phosphorus concentrations was co
llected at days 1, 3, 7, and 14 of the study period. A 24-hour urine collec
tion was obtained during the first and second weeks of nutrition support fo
r urinary phosphorus excretion, fractional excretion of phosphorus, renal t
hreshold phosphate concentration, and phosphorus clearance. Average total d
aily phosphorus intake during the 14-day study for thermally injured patien
ts and multiple trauma patients was 0.99 0.26 mmol/kg/d vs 0.58 +/- 0.21 mm
ol/kg/d, respectively, p < .001. Serum phosphorus concentration on the thir
d day of observation was significantly lower in the thermally injured group
than those with multiple trauma (1.9 +/- 0.8 mg/dL vs 3.0 +/- 0.8 mg/dL, p
less than or equal to .01). A trend toward hypophosphatemia in the thermal
ly injured group persisted by the seventh day of feeding (2.7 +/- 1.2 mg/dL
vs 3.3 +/- 0.6 mg/dL, p less than or equal to .04). Differences in urinary
phosphorus excretion was not statistically significant between the thermal
ly injured and multiple trauma groups (271 +/- 213 mg/d vs 171 +/- 181 mg/d
for week 1, and 320 +/- 289 mg/d vs 258 +/- 184 mg/d for week 2, respectiv
ely). Urinary phosphorus clearance, fractional excretion of phosphorus, or
renal threshold phosphate concentrations were also not significantly differ
ent between thermally injured and multiple trauma patients. During nutritio
n support, serum phosphorus concentrations are lower in thermally injured p
atients compared with multiple trauma patients despite receiving a signific
antly greater intake of phosphorus. Renal phosphorus regulation does not si
gnificantly contribute to the profound hypophosphatemia observed in thermal
ly injured patients when compared with multiple trauma patients during nutr
ition support.