# Creatinine Clearance Calculator

> Estimates creatinine clearance in mL/min with the Cockcroft-Gault equation from age, weight, sex and serum creatinine, and, when height is given, also reports the values using ideal (Devine) and adjusted body weight.

- Calculator id: `creatinine-clearance` · Category: Medical & Clinical (`medical`) · Tool name: `calculate_creatinine_clearance`
- Canonical page: https://tttkmbb.com/medical/creatinine-clearance · This document: https://tttkmbb.com/medical/creatinine-clearance.md · JSON definition: https://tttkmbb.com/medical/creatinine-clearance.json

## Purpose

Estimates creatinine clearance in mL/min with the Cockcroft-Gault equation from age, weight, sex and serum creatinine, and, when height is given, also reports the values using ideal (Devine) and adjusted body weight.

**Use when:** You need the creatinine clearance used by drug-dosing references (renal dose adjustment) for an adult.

**Do not use when:** You need a BSA-indexed CKD stage (use egfr), the person is under 18, or creatinine is changing rapidly (acute kidney injury).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `sex` | enum: male \| female |  | required | Sex used to select the formula coefficients or thresholds. |
| `age_years` | number | years | required | Age in years. (min 18, max 120) |
| `weight_kg` | number | kg | required | Actual body weight in kilograms. (> 0, max 700) |
| `creatinine` | number |  | required | Serum creatinine in the unit given by creatinine_unit. (> 0, max 4000) |
| `creatinine_unit` | enum: mg_dl \| umol_l |  | optional, default "mg_dl" | Unit of the serum creatinine value (1 mg/dL = 88.4 µmol/L). |
| `height_cm` | number | cm | optional | Optional height; enables ideal-body-weight and adjusted-body-weight variants. (min 120, max 260) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `creatinine_clearance_ml_min` | number | mL/min | Cockcroft-Gault clearance using actual body weight. |
| `ideal_body_weight_kg` | number | kg | Only when height_cm is given. |
| `adjusted_body_weight_kg` | number | kg | IBW + 0.4 × (actual − IBW); only when height_cm is given. |
| `creatinine_clearance_ibw_ml_min` | number | mL/min | Cockcroft-Gault using ideal body weight; only when height_cm is given. |
| `creatinine_clearance_adjusted_ml_min` | number | mL/min | Cockcroft-Gault using adjusted body weight; only when height_cm is given. |
| `weight_note` | string |  | Which weight is commonly used for this body size. |

## Formula

`CrCl = (140 − age_years) × weight_kg / (72 × Scr_mg_dl) × 0.85 (if female); IBW (Devine) = 50 (male) or 45.5 (female) + 2.3 × (height_in − 60); adjusted BW = IBW + 0.4 × (weight − IBW)`

Cockcroft-Gault (1976) overestimates clearance in obesity when actual weight is used and in low muscle mass; many references use ideal weight when actual is below it and adjusted weight above 120–130% of ideal. Results are informational only and not a substitute for clinical judgement or medical advice.

## Data Sources

- Cockcroft DW, Gault MH (1976) Prediction of creatinine clearance from serum creatinine, Nephron 16:31-41 — https://pubmed.ncbi.nlm.nih.gov/1244564/ (peer_reviewed, retrieved 2026-09-24)
- Pai MP, Paloucek FP (2000) The origin of the 'ideal' body weight equations, Ann Pharmacother 34:1066-1069 — https://pubmed.ncbi.nlm.nih.gov/10981254/ (peer_reviewed, retrieved 2026-09-24)
- Winter MA et al. (2012) Impact of various body weights and serum creatinine concentrations on the bias and accuracy of the Cockcroft-Gault equation, Pharmacotherapy 32:604-612 — https://pubmed.ncbi.nlm.nih.gov/22576791/ (peer_reviewed, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/creatinine-clearance?sex=…&age_years=…&weight_kg=…&creatinine=…`
- `POST https://tttkmbb.com/api/v1/calculate/creatinine-clearance` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/creatinine-clearance · OpenAPI operationId `calculate_creatinine_clearance` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "creatinine-clearance", "inputs": {…}}`

## Example

- Male, 40 y, 70 kg, creatinine 1.0 mg/dL: inputs `{"sex":"male","age_years":40,"weight_kg":70,"creatinine":1}` → `{"creatinine_clearance_ml_min":97.2}`
- Female, 65 y, 60 kg, 160 cm, creatinine 0.8 mg/dL: inputs `{"sex":"female","age_years":65,"weight_kg":60,"creatinine":0.8,"height_cm":160}` → `{"creatinine_clearance_ml_min":66.4,"ideal_body_weight_kg":52.4,"creatinine_clearance_ibw_ml_min":58}`

```
GET https://tttkmbb.com/api/v1/calculate/creatinine-clearance?sex=male&age_years=40&weight_kg=70&creatinine=1
```

## Limitations

You need a BSA-indexed CKD stage (use egfr), the person is under 18, or creatinine is changing rapidly (acute kidney injury). Cockcroft-Gault (1976) overestimates clearance in obesity when actual weight is used and in low muscle mass; many references use ideal weight when actual is below it and adjusted weight above 120–130% of ideal. Results are informational only and not a substitute for clinical judgement or medical advice. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Which weight should I use?**

Common practice: actual weight when it is below ideal weight, ideal weight for normal-weight adults, and adjusted weight when actual weight exceeds about 120% of ideal; follow the specific drug's labelling.

**Why is creatinine clearance different from eGFR?**

Cockcroft-Gault is an unindexed estimate in mL/min derived in 1976 for a small male cohort; eGFR (CKD-EPI) is indexed to 1.73 m² and validated for staging CKD, not dosing.

## Related

- [eGFR Calculator](https://tttkmbb.com/medical/egfr.md) — CKD-EPI 2021 eGFR for staging kidney disease.
- [Adjusted Body Weight Calculator](https://tttkmbb.com/medical/adjusted-body-weight.md) — Adjusted body weight for dosing in obesity.
- [Ideal Weight Calculator](https://tttkmbb.com/health/ideal-weight.md) — Ideal body weight formulas.