Health
Fractional Excretion of Sodium (FENa)
Calculate the Fractional Excretion of Sodium (FENa) to differentiate prerenal from intrinsic acute kidney injury: FENa (%) = [U_Na × S_Cr] / [S_Na × U_Cr] × 100. In oliguric AKI, FENa <1% suggests prerenal azotemia (sodium-avid state: volume depletion, heart failure, hepatorenal syndrome), while FENa ≥1% suggests intrinsic injury (typically ATN). FENa >4% is sometimes cited as supportive of post-obstructive pathology. Caveats: unreliable on diuretics (use FEUrea <35%), contrast/sepsis ATN can present with low FENa, chronic CKD and glucosuria elevate FENa independently. Derived from Espinel CH, JAMA 1976. Most useful in oliguric AKI; interpret with full clinical context. Not medical advice.
Quick start
Call this tool from your code in three languages.
curl -X POST 'https://api.elysiatools.com/en/api/tools/fractional-excretion-sodium' \
-H 'Content-Type: application/json' \
-d '{"urineSodium":20,"serumCreatinine":1.5,"serumSodium":140,"urineCreatinine":120,"decimalPlaces":4}'API reference
Send a POST request with your inputs as JSON. File parameters require a separate upload first.
Endpoint
POST https://api.elysiatools.com/en/api/tools/fractional-excretion-sodiumParameters
| Name | Type | Required | Description |
|---|---|---|---|
| urineSodium | number | Yes | Urine sodium concentration in mmol/L. Must be ≥0. |
| serumCreatinine | number | Yes | Serum creatinine in mg/dL. Must be positive. |
| serumSodium | number | Yes | Serum sodium concentration in mmol/L. Must be positive. |
| urineCreatinine | number | Yes | Urine creatinine concentration in mg/dL. Must be positive. |
| decimalPlaces | number |
MCP integration
Add this tool to your Model Context Protocol server so AI agents can list and call it.
Server configuration
Add this block to your MCP client configuration:
{
"mcpServers": {
"elysiatools-fractional-excretion-sodium": {
"name": "fractional-excretion-sodium",
"description": "Calculate the Fractional Excretion of Sodium (FENa) to differentiate prerenal from intrinsic acute kidney injury: FENa (%) = [U_Na × S_Cr] / [S_Na × U_Cr] × 100. In oliguric AKI, FENa <1% suggests prerenal azotemia (sodium-avid state: volume depletion, heart failure, hepatorenal syndrome), while FENa ≥1% suggests intrinsic injury (typically ATN). FENa >4% is sometimes cited as supportive of post-obstructive pathology. Caveats: unreliable on diuretics (use FEUrea <35%), contrast/sepsis ATN can present with low FENa, chronic CKD and glucosuria elevate FENa independently. Derived from Espinel CH, JAMA 1976. Most useful in oliguric AKI; interpret with full clinical context. Not medical advice.",
"baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=fractional-excretion-sodium",
"command": "",
"args": [],
"env": {},
"isActive": true,
"type": "sse"
}
}
}List available tools
After connecting to the SSE endpoint, list the exposed tools:
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/list"
}Call this tool
Invoke the tool by its id, passing arguments built from its parameters:
{
"jsonrpc": "2.0",
"id": 2,
"method": "tools/call",
"params": {
"name": "fractional-excretion-sodium",
"arguments": {
"urineSodium": 20,
"serumCreatinine": 1.5,
"serumSodium": 140,
"urineCreatinine": 120,
"decimalPlaces": 4
}
}
}