# OSTA Osteoporosis Risk Calculator (Koh 2001)

> OSTA Osteoporosis Risk Calculator (Koh 2001) is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Computes the Osteoporosis Self-Assessment Tool for Asians (OSTA) index and risk category (low, intermediate, high) from patient age and weight

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/osta
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/osta-osteoporosis-risk-calculator-koh-2001-eb0a3bf7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Qtwz7Np_jDkU1f4_dSYra

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 osta-osteoporosis-risk-calculator-koh-2001-eb0a3bf7
```

Example prompt: Can you run the OSTA osteoporosis risk screen for a 68-year-old patient who weighs 52 kg and tell me if she's low, intermediate, or high risk?

## When to prefer this

Use this endpoint when you need a fast, validated, formulaic osteoporosis pre-screen based solely on age and weight for postmenopausal Asian women, following the Koh 2001 OSTA derivation. Prefer this over FRAX when bone mineral density data and fracture history are unavailable and a simple two-variable index suffices. Not appropriate for men, non-Asian populations, or as a substitute for DXA imaging.

## Known failure modes

- Missing required 'age' parameter returns a validation error
- Age outside 18–120 range may be rejected or return an error
- Neither weight_kg nor weight_lb provided leads to incomplete calculation
- Non-integer age value may cause schema validation failure
- Network or payment (x402) failure if USDC balance is insufficient

## How this service works

Koh 2001 Osteoporosis Self-Assessment Tool for Asians (OSTA). Index = trunc(0.2 × (weight_kg − age)) toward zero. Risk low if index > −1, intermediate if −1 through −4, high if index < −4. Age 18–120; weight_kg or weight_lb. Not a medical device, not FRAX, not a DXA order. Derivation was postmenopausal Asian women.

## Output

Returns the numeric OSTA index (truncated toward zero from 0.2 × (weight_kg − age)) and a categorical risk level: low (index > −1), intermediate (index −1 through −4), or high (index < −4). Not a DXA order, not FRAX, and not validated outside postmenopausal Asian women.

## 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": [
      "age"
     ],
     "properties": {
      "age": {
       "type": "integer",
       "description": "Age in years (18-120). Koh 2001 OSTA uses age as a whole number of years."
      },
      "weight_kg": {
       "type": "number",
       "description": "Weight in kilograms. Provide weight_kg or weight_lb."
      },
      "weight_lb": {
       "type": "number",
       "description": "Weight in pounds. Converted as kg = lb * 0.45359237."
      }
     }
    }
   },
   "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/osta-osteoporosis-risk-calculator-koh-2001-eb0a3bf7/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)