A systematic literature search and review of sodium concentrations of body fluids .

Background: Wide ranges of sodium concentrations for different body fluid losses have been noted with minimal substantiating data and variability among sources, leading to use of "cumulative fluid balance" regardless of composition in hospitalized patients.

Aims: To define the sodium concentrations of fluid losses from the body.

Method: We performed a systematic search and literature review in adult humans using PubMed database.

Results: Inclusion criteria were met for 107 full-text articles. Mean sodium concentrations were significantly lower for acidic (mean ± SD: 44 ± 12 mEq/L) than for alkaline (55 ± 13 mEq/L) gastric fluid, higher for bile (185 ± 24 mEq/L) or pancreatic fluid (156 ± 3 mEq/L) than for all other body fluids, and similar for intact small bowel (119 ± 14 mEq/L) and ileostomy outputs (116 ± 25 mEq/L). Sodium concentrations were significantly greater for cholera-induced diarrhea (128 ± 18 mEq/L) and lower for osmotic-induced diarrhea (28 ± 16 mEq/L) than all other causes of diarrhea. For osmotic diarrheas, sorbitol-induced diarrhea sodium concentration was higher (63 ± 17 mEq/L) than for carbohydrate malabsorption (43 ± 20 mEq/L), lactulose (26 ± 19 mEq/L), Idolax (16 ± 13 mEq/L), or polyethylene glycol (13 ± 7 mEq/L). For secretory diarrheas, sodium concentration for idiopathic causes (53 ± 22 mEq/L) was lower than for neuroendocrine and villous tumors (75 ± 13 mEq/L) or nonosmotic laxatives (88 ± 33 mEq/L). For pleural, peritoneal, and edema fluid, sodium concentrations (137 ± 13 mEq/L) were similar to plasma. No data were found for wound fluid. Sodium concentration for sweat was 44 ± 17 mEq/L.

Conclusions: This is the first in-depth review of verifiable sodium concentrations of body fluids most commonly lost in hospitalized patients. Sodium concentrations are fluid-specific and consistent. Sodium concentrations for diarrhea are associated with specific mechanisms/causes. These data should be useful to more accurately replace sodium and water content for specific body fluid losses.
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