# PASI Calculator (Fredriksson 1978)

> PASI Calculator (Fredriksson 1978) 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 Psoriasis Area and Severity Index (PASI) score from caller-supplied area, erythema, induration, and scaling values across four body regions.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/pasi
- 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/pasi-calculator-fredriksson-1978-05a5be68
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_i2DtGPgme-PHAtyqkHON0

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 pasi-calculator-fredriksson-1978-05a5be68
```

Example prompt: Calculate the PASI score for my patient: head area 2, erythema 2, induration 1, scaling 2; upper extremities area 3, erythema 3, induration 2, scaling 2; trunk area 4, erythema 2, induration 2, scaling 3; lower extremities area 3, erythema 2, induration 1, scaling 2.

## When to prefer this

Use this endpoint when you need a standards-compliant Fredriksson 1978 PASI score computed from discrete clinical observations you have already gathered. It is the right choice for automating PASI arithmetic in EHR workflows, clinical trial data pipelines, or telemedicine tools where a clinician has already assessed the patient. Do not use it if you need EASI scoring, IGA grading, pediatric adjustments, or any diagnostic interpretation — it returns a raw numeric score only.

## Known failure modes

- Missing any of the 16 required query parameters returns an error
- Out-of-range area values (outside 0–6) or sign values (outside 0–4) are rejected
- Invalid data types (non-integer or floating-point) for area or sign fields cause validation failure
- No partial scoring — all four regions must be supplied

## How this service works

Fredriksson 1978 PASI from four regions. Each region: area 0-6 and erythema, induration, and scaling 0-4. Region score = (sum of three signs) × area × adult weight (head 0.1, upper extremities 0.2, trunk 0.3, lower extremities 0.4). Total max 72. Adult weights only. magent does not examine the skin. No IGA or later severity bands. Not a diagnosis. Not EASI.

## Output

Returns the total PASI score on a 0–72 scale, calculated using the Fredriksson 1978 formula: each region's sign sum (erythema + induration + scaling, each 0–4) is multiplied by the area score (0–6) and the region's adult body-surface weight (head 0.1, upper extremities 0.2, trunk 0.3, lower extremities 0.4). Regional sub-scores and the aggregate total are returned. The endpoint performs arithmetic only and does not include IGA bands, EASI scoring, or diagnostic interpretation.

## 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": [
      "head_area",
      "head_erythema",
      "head_induration",
      "head_scaling",
      "upper_extremities_area",
      "upper_extremities_erythema",
      "upper_extremities_induration",
      "upper_extremities_scaling",
      "trunk_area",
      "trunk_erythema",
      "trunk_induration",
      "trunk_scaling",
      "lower_extremities_area",
      "lower_extremities_erythema",
      "lower_extremities_induration",
      "lower_extremities_scaling"
     ],
     "properties": {
      "head_area": {
       "enum": [
        0,
        1,
        2,
        3,
        4,
        5,
        6
       ],
       "type": "integer",
       "description": "Caller-assigned Fredriksson 1978 PASI area of involvement for this body region (integer 0-6): 0 none, 1 <10%, 2 10-29%, 3 30-49%, 4 50-69%, 5 70-89%, 6 90-100%. magent does not examine the skin."
      },
      "trunk_area": {
       "enum": [
        0,
        1,
        2,
        3,
        4,
        5,
        6
       ],
       "type": "integer",
       "description": "Caller-assigned Fredriksson 1978 PASI area of involvement for this body region (integer 0-6): 0 none, 1 <10%, 2 10-29%, 3 30-49%, 4 50-69%, 5 70-89%, 6 90-100%. magent does not examine the skin."
      },
      "head_scaling": {
       "enum": [
        0,
        1,
        2,
        3,
        4
       ],
       "type": "integer",
       "description": "Caller-assigned Fredriksson 1978 PASI scaling for this region (integer 0-4): 0 none, 1 slight, 2 moderate, 3 severe, 4 very severe. magent does not examine the skin."
      },
      "head_erythema": {
       "enum": [
        0,
        1,
        2,
        3,
        4
       ],
       "type": "integer",
       "description": "Caller-assigned Fredriksson 1978 PASI erythema for this region (integer 0-4): 0 none, 1 slight, 2 moderate, 3 severe, 4 very severe. magent does not examine the skin."
      },
      "trunk_sc
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pasi-calculator-fredriksson-1978-05a5be68/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)