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Serum Osmolality Calculator (Worthley 1987 + Osmolar Gap)
x402
Serum Osmolality Calculator (Worthley 1987 + Osmolar Gap) 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).
Calculates estimated serum osmolality using the Worthley 1987 formula (2×Na + glucose/18 + BUN/2.8) and optionally computes the osmolar gap when a measured osmolality is provided.
Price / call$0.005
Success—
StatusUnknown
How this service works
Worthley 1987 calculated serum osmolality: 2×Na + glucose/18 + BUN/2.8. Optional osmolar gap when a measured osm is supplied. Deterministic published arithmetic with citation; not a measured freezing-point osmometer or a diagnosis.
Output
Returns the calculated serum osmolality in mOsm/kg using the Worthley 1987 formula (2×Na + glucose/18 + BUN/2.8). When a measured osmolality is supplied, also returns the osmolar gap (measured minus calculated). Includes citation metadata confirming the deterministic arithmetic used.
Example use cases
Osmolar gap screen for toxic alcohol
“My patient has sodium 140, BUN 18, glucose 95 mg/dL, and the lab measured osmolality at 325 mOsm/kg — can you calculate the osmolar gap so I can assess for possible toxic alcohol ingestion?”
Hypernatremia workup osmolality
“Run the Worthley serum osmolality on these labs: sodium 155 mmol/L, BUN 35 mg/dL, glucose 180 mg/dL. No measured osm available.”
ICU fluid management check
“For an ICU patient with sodium 132, BUN 28 mg/dL, and glucose 210 mg/dL, calculate their estimated serum osmolality — and the osmolar gap if the measured value is 295 mOsm/kg.”
Technical details
Endpoint
GEThttps://api.magentlab.com/api/calc/serum_osmolalityWhen to prefer
Use this endpoint when you need a fast, deterministic, citation-backed serum osmolality calculation following the Worthley 1987 formula, especially when you also want an osmolar gap derived from a measured value. Prefer this over manual arithmetic to ensure correct unit conversions (glucose mmol/L support) and validated input ranges. Not a substitute for a freezing-point osmometer or clinical diagnosis.
Side effects
- Missing required parameters (sodium_mmol_l or bun_mg_dl not provided) — returns validation error
- Sodium out of range (110–160 mmol/L) — returns range error
- BUN out of range (1–200 mg/dL) — returns range error
- Glucose out of range (50–1000 mg/dL or 2.8–55.5 mmol/L) — returns range error
- Measured osmolality out of range (200–400 mOsm/kg) — returns range error
- Payment not completed (x402 protocol) — returns 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"path": "/api/calc/serum_osmolality",
"count": 2,
"items": [
{
"formula": "worthley",
"citation": {
"id": "worthley-1987",
"doi": "10.1177/0310057X8701500214",
"title": "For calculating osmolality, the simplest formula is the best",
"source": "Anaesth Intensive Care. 1987;15(2):199-202",
"authors": "Worthley LI, Guerin M, Pain RW"
},
"bun_mg_dl": 14,
"disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
"glucose_mg_dl": 90,
"sodium_mmol_l": 140,
"formula_expression": "calculated_osm_mosm_kg = 2 * sodium_mmol_l + glucose_mg_dl / 18 + bun_mg_dl / 2.8",
"calculated_osm_mosm_kg": 290
},
{
"formula": "worthley",
"citation": {
"id": "worthley-1987",
"doi": "10.1177/0310057X8701500214",
"title": "For calculating osmolality, the simplest formula is the best",
"source": "Anaesth Intensive Care. 1987;15(2):199-202",
"authors": "Worthley LI, Guerin M, Pain RW"
},
"bun_mg_dl": 14,
"disclaimer": "Not a medical device. Deterministic published-formula or published-code output for autonomous agents. A licensed clinician remains responsible for patient care and billing submissions.",
"glucose_mg_dl": 90,
"sodium_mmol_l": 140,
"formula_expression": "calculated_osm_mosm_kg = 2 * sodium_mmol_l + glucose_mg_dl / 18 + bun_mg_dl / 2.8",
"calculated_osm_mosm_kg": 290
}
]
}
}Tags
x402
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