URR calculator

Pre-dialysis urea must be a finite number greater than zero; a zero pre-dialysis value cannot define a ratio and fails with invalid_input. Successful API calls use the published $0.002 per item; invalid input is not billed.

What the urea reduction ratio measures and which inputs you need

Send required field pre_urea as the pre-dialysis concentration and required field post_urea as the post-dialysis concentration; aliases such as pre_bun, bun_pre, pre_dialysis_bun, post_bun, and c_post are accepted when documented. Identical inputs always yield identical JSON because the path is pure arithmetic with no network, no model, no random seed, and no wall clock.

Reading the percentage, response fields, and error paths

The unit field is always percent. A textbook adequacy-threshold pair of one hundred and thirty-five yields sixty-five percent. Equal pre and post concentrations yield a zero percent URR, which is a valid if poor session arithmetic rather than an error. Negative concentrations fail because a negative urea reading is not a valid laboratory input for this calculator. On success the JSON echoes the cleaned pre_urea and post_urea values, reports urea_removed as pre minus post in the same concentration unit, and reports urr as that difference divided by pre times one hundred. The formula string restates URR equals open parenthesis pre minus post close parenthesis over pre times one hundred, and method is always urea_reduction_ratio so downstream code can branch without sniffing shapes. Use urr alone when you only need the percentage for a worksheet; use urea_removed when teaching the numerator of the identity. A classic adult example of pre-dialysis eighty and post-dialysis twenty-four yields urea_removed fifty-six and a seventy percent URR. Missing fields, empty strings, non-numeric text, NaN, and Infinity fail with invalid_input naming the field. A zero pre_urea fails with a message that a zero pre-dialysis urea cannot define a urea reduction ratio, because the percentage would require division by zero. When post_urea exceeds pre_urea, the task returns invalid_input stating that post-dialysis urea cannot be greater than pre-dialysis urea, and the call is not billed. Do not confuse this endpoint with Kt/V, equilibrated Kt/V, standard Kt/V, or urea generation models—those are different search intents and different contracts. Pricing for successful API calls is the published $0.002 per item; validation failures do not consume prepaid balance.

API usage, pricing, product workflows, and practical limits

Send a JSON body with required pre_urea and post_urea values in the same concentration unit. Use the prepaid API when a health SaaS, electronic worksheet, simulation lab, tutoring platform, or school LMS needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with your own laboratory units and workflow—confirm that both readings are BUN in milligrams per decilitre or both are urea in millimoles per litre, not a mixed pair—then store urr alongside the raw panel for dashboards. Authors shipping SDKs can map urr into tables, educational reference bands you define yourself, and step-by-step teaching cards that show the formula string and urea_removed.