Fractional excretion of urea (FEUN) from BUN, urine urea nitrogen, and plasma/ur
Fractional excretion of urea (FEUN) from BUN, urine urea nitrogen, and plasma/urine creatinine (Carvounis 2002). Use when diuretics make FENa unhelpful. Deterministic published formula with citation; not a diagnosis.
Asked 1.4x its listed price for its own exampleour last check, 2026-09-28
1 of 1checks answered this week
266 msmedian answer time
$0.005listed price per call
$0.007price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://api.magentlab.com/api/calc/feurea
| Category | Everything else |
|---|---|
| Provider host | api.magentlab.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 0 from 0 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-28 | valid payment request | 402 | $0.007 | 266 ms |
Example input (from the provider)
{
"body": {
"items": [
{
"bun_mg_dl": 20,
"creatinine_mg_dl": 2,
"creatinine_umol_l": 176.84,
"urine_creatinine_mg_dl": 100,
"urine_creatinine_umol_l": 8842,
"urine_urea_mg_dl": 200
},
{
"bun_mg_dl": 20,
"creatinine_mg_dl": 2,
"creatinine_umol_l": 176.84,
"urine_creatinine_mg_dl": 100,
"urine_creatinine_umol_l": 8842,
"urine_urea_mg_dl": 200
}
]
},
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"properties": {
"items": {
"items": {
"properties": {
"bun_mg_dl": {
"description": "Blood urea nitrogen in mg/dL (1-200). Same units as urine urea nitrogen.",
"type": "number"
},
"creatinine_mg_dl": {
"description": "Plasma creatinine in mg/dL. Provide this or creatinine_umol_l.",
"type": "number"
},
"creatinine_umol_l": {
"description": "Plasma creatinine in \u00b5mol/L. Converted as mg/dL = \u00b5mol/L / 88.42.",
"type": "number"
},
"urine_creatinine_mg_dl": {
"description": "Urine creatinine in mg/dL (1-500). Provide this or urine_creatinine_umol_l.",
"type": "number"
},
"urine_creatinine_umol_l": {
"description": "Urine creatinine in \u00b5mol/L (88-44210). Converted as mg/dL = \u00b5mol/L / 88.42.",
"type": "number"
},
"urine_urea_mg_dl": {
"description": "Urine urea nitrogen in mg/dL (1-2000). Same units as BUN.",
"type": "number"
}
},
"required": [
"bun_mg_dl",
"urine_urea_mg_dl"
],
"type": "object"
},
"maxItems": 25,
"minItems": 1,
"type": "array"
}
},
"required": [
"items"
],
"type": "object"
},
"headers": {
"additionalProperties": {
"type": "string"
},
"type": "object"
},
"method": {
"const": "POST",
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}