{"uid":"cap_hQ6ePDepZL1l_mS1R0joX","slug":"bun-creatinine-ratio-calculator-richards-1990-43d652dc","name":"BUN/Creatinine Ratio Calculator (Richards 1990)","description":"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.","url":"https://api.magentlab.com/api/calc/bun_creatinine_ratio","method":"GET","headers":{},"bodySchema":{"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"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_UqTIqVlBFudyHY8n3Bc_A","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the BUN-to-creatinine ratio and flags whether it meets the Richards 1990 threshold (≥36) suggesting upper gastrointestinal bleeding.","exampleAgentPrompt":"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?","exampleUseCases":[{"title":"ED triage for GI bleed source","prompt":"My ED patient has a BUN of 72 mg/dL and a creatinine of 1.8 mg/dL — calculate the BUN to creatinine ratio and tell me if it hits the Richards 1990 cutoff of 36 suggesting upper GI bleeding."},{"title":"ICU lab review with SI units","prompt":"I have a creatinine of 115 µmol/L and a BUN of 28 mg/dL for my ICU patient — compute the BUN/creatinine ratio for me and flag whether it's above or below 36."},{"title":"Hospitalist rounding decision support","prompt":"Can you work out the Richards BUN/creatinine ratio for a BUN of 90 mg/dL and creatinine of 2.5 mg/dL, and let me know if that's consistent with an upper GI source?"}],"resultDescription":"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.","failureModes":["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"],"whenToPreferThis":"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.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T06:57:44.268Z","isFirstParty":false}