# BUN/Creatinine Ratio Calculator (Richards 1990)

> BUN/Creatinine Ratio Calculator (Richards 1990) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Computes the BUN-to-creatinine ratio and flags whether it meets the Richards 1990 threshold (≥36) suggesting upper gastrointestinal bleeding.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/bun_creatinine_ratio
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/bun-creatinine-ratio-calculator-richards-1990-43d652dc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hQ6ePDepZL1l_mS1R0joX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability bun-creatinine-ratio-calculator-richards-1990-43d652dc
```

Example prompt: My patient has a BUN of 45 mg/dL and a creatinine of 1.2 mg/dL — can you compute the Richards 1990 BUN/creatinine ratio and tell me whether it meets the ≥36 threshold for suspected upper GI bleeding?

## When to prefer this

Use this endpoint when you need a fast, single-call computation of the Richards 1990 BUN/creatinine ratio from discrete lab values. Prefer it when your agent already holds BUN and creatinine values and needs to apply the ≥36 threshold for upper GI bleeding risk stratification. If you need Glasgow-Blatchford scoring or ADHERE CART classification, use the corresponding sibling endpoints instead.

## Known failure modes

- Both creatinine_mg_dl and creatinine_umol_l provided simultaneously — endpoint rejects the request
- BUN value outside 1–200 mg/dL range — validation error
- Creatinine mg/dL outside 0.1–20 range or µmol/L outside 9–1768 — validation error
- Missing required bun_mg_dl parameter — returns error
- Non-numeric input for numeric fields — returns error

## How this service works

Richards 1990 BUN/creatinine ratio as bun_mg_dl / creatinine_mg_dl, rounded to one decimal. A ratio of 36 or greater suggests upper gastrointestinal bleeding. A ratio below 36 is not helpful in locating the source and is not a lower-GI class. Provide creatinine_mg_dl (0.1-20) or creatinine_umol_l (9-1768), not both. Not a diagnosis, endoscopy order, or Blatchford urea band. magent does not locate a bleed.

## Output

Returns the BUN/creatinine ratio rounded to one decimal place, along with an indication of whether the ratio is ≥36 (suggestive of upper GI bleeding per Richards 1990). Does not provide a diagnosis, endoscopy order, or localization of the bleeding site.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "bun_mg_dl"
     ],
     "properties": {
      "bun_mg_dl": {
       "type": "number",
       "description": "Blood urea nitrogen in mg/dL (1-200). Richards 1990 ratio uses BUN in mg/dL. Not a Glasgow-Blatchford urea band. magent does not assay BUN."
      },
      "creatinine_mg_dl": {
       "type": "number",
       "description": "Serum creatinine in mg/dL (0.1-20). Provide this or creatinine_umol_l, not both. magent does not assay creatinine."
      },
      "creatinine_umol_l": {
       "type": "number",
       "description": "Serum creatinine in µmol/L (9-1768). Converted as mg/dL = µmol/L / 88.42. Provide this or creatinine_mg_dl, not both."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/bun-creatinine-ratio-calculator-richards-1990-43d652dc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)