Langcare Langcare MCP Fhir Critical Value Alert Generator

Critical Value Alert Generator

Overview

Scan recent laboratory Observation resources for values exceeding critical thresholds defined by CAP (College of American Pathologists) and CLIA guidelines. Generate structured alerts containing: the critical value, threshold exceeded, clinical significance, and recommended immediate action. Support read-back verification workflow for clinical notification compliance. Prioritize alerts by clinical urgency.

FHIR Resources Used

Instructions

Step 1: Retrieve Patient Demographics

Tool: fhir_read
resourceType: "Patient"
id: "[patient-id]"

Extract name (for alert addressee), age (pediatric thresholds differ), gender.

Step 2: Pull Recent Laboratory Observations

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&category=laboratory&date=ge[24-hours-ago]&_sort=-date&_count=200"

Default scan window: 24 hours. Expand to 48 or 72 hours if user requests or if investigating missed alerts.

Step 3: Screen Against Critical Value Thresholds

For each Observation, compare valueQuantity.value against critical thresholds.

Priority 1 -- Immediately Life-Threatening:

Priority 2 -- Urgent (within 1 hour):

Priority 3 -- Urgent Drug Levels:

See references/critical-value-table.md for complete thresholds with pediatric adjustments.

Also check the interpretation field: codes HH (critical high) or LL (critical low) from the FHIR server itself may flag values the threshold table does not cover.

Step 4: Retrieve Clinical Context for Each Critical Value

For each critical value found:

Tool: fhir_search
resourceType: "MedicationStatement"
queryParams: "patient=[patient-id]&status=active"

Tool: fhir_search
resourceType: "Condition"
queryParams: "patient=[patient-id]&clinical-status=active"

Correlate:

• Critical potassium + ACE inhibitor/ARB/spironolactone = drug-induced hyperkalemia
• Critical potassium low + loop diuretic = drug-induced hypokalemia
• Critical INR + warfarin = supratherapeutic anticoagulation
• Critical glucose low + insulin/sulfonylurea = drug-induced hypoglycemia
• Critical lithium + renal impairment = accumulation risk
• Critical troponin + known CAD = acute coronary syndrome context

Step 5: Check for Prior Value (Delta)

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=[loinc-code]&_sort=-date&_count=2"

Compare current critical value to the most recent prior result. Note whether the value is newly critical or has been trending toward critical.

Step 6: Generate Structured Alert

For each critical value, produce an alert block:

=====================================================
CRITICAL VALUE ALERT -- PRIORITY [1/2/3]
=====================================================
Patient:    [Name] (MRN: [id])
Test:       [Analyte name]
Value:      [result] [unit]
Threshold:  [critical low/high threshold]
Collected:  [effectiveDateTime]
Prior:      [prior value] on [prior date] (delta: [change])

CLINICAL SIGNIFICANCE:
[1-2 sentence explanation of the clinical risk]

RECOMMENDED IMMEDIATE ACTIONS:
1. [First action -- most urgent]
2. [Second action]
3. [Third action]

MEDICATION CONTEXT:
- [Relevant active medication and its relationship to the critical value]

READ-BACK VERIFICATION:
"The critical value for [Patient Name] is [analyte] of [value] [unit],
collected at [time]. The critical threshold is [threshold]. Please
read back the patient name, test name, and value to confirm receipt."
=====================================================

Step 7: Prioritize and Order Alerts

Sort alerts by:

1. Priority level (1 before 2 before 3)
2. Within same priority, by clinical urgency (e.g., potassium 2.0 before potassium 2.4)
3. Timestamp (most recent first within same analyte)

If no critical values found, report: "No critical values detected in laboratory results from [date range]. [N] total observations reviewed."

Examples

Example 1: Multiple Critical Values Detected

User says: "Check for critical labs on patient 33201"

Actions:

1. fhir_read Patient/33201 -- returns 58-year-old male, John Martinez
2. fhir_search Observation?patient=33201&category=laboratory&date=ge[24-hours-ago]&_sort=-date&_count=200 -- returns 12 results; potassium 6.8 mEq/L (HH), glucose 38 mg/dL (LL), hemoglobin 6.2 g/dL (L)
3. fhir_search MedicationStatement?patient=33201&status=active -- returns spironolactone, insulin glargine, aspirin
4. fhir_search Condition?patient=33201&clinical-status=active -- returns CKD stage 4, Type 2 DM, CHF
5. fhir_search Observation?patient=33201&code=2823-3&_sort=-date&_count=2 -- prior potassium 5.8 two days ago
6. fhir_search Observation?patient=33201&code=2345-7&_sort=-date&_count=2 -- prior glucose 95 yesterday
7. fhir_search Observation?patient=33201&code=718-7&_sort=-date&_count=2 -- prior hemoglobin 7.1 one week ago

Result: Three alerts generated:

• PRIORITY 1: Potassium 6.8 (threshold > 6.5), trending up from 5.8. Spironolactone + CKD4 causative. Action: ECG stat, calcium gluconate, hold spironolactone, kayexalate.
• PRIORITY 1: Glucose 38 (threshold < 40), prior was 95. Insulin glargine causative. Action: D50 IV push, recheck in 15 min, hold insulin pending evaluation.
• PRIORITY 2: Hemoglobin 6.2 (threshold < 7.0), dropping from 7.1. Action: Type and screen, transfuse 1 unit pRBC, evaluate for active bleeding.

Example 2: No Critical Values Found

User says: "Any critical labs for patient abc-100 in the last 48 hours?"

Actions:

1. fhir_read Patient/abc-100 -- returns 34-year-old female
2. fhir_search Observation?patient=abc-100&category=laboratory&date=ge[48-hours-ago]&_sort=-date&_count=200 -- returns 8 results; all within normal limits or mildly abnormal (e.g., LDL 142 mg/dL flagged H)

Result: "No critical values detected in laboratory results from the past 48 hours. 8 total observations reviewed. Note: 1 non-critical abnormality -- LDL 142 mg/dL (above reference 0-130). No immediate action required."

Troubleshooting

FHIR Server Does Not Use interpretation Coding

• Some servers omit the interpretation field entirely. Rely on threshold comparison against valueQuantity.value using the critical value table.
• If valueQuantity is also absent, check valueString -- some results are reported as text (e.g., "> 500" for troponin). Parse the numeric value from the string.

Observation Uses Different Units Than Expected

• Potassium may be reported as mmol/L instead of mEq/L (1:1 conversion for monovalent ions, so thresholds are the same).
• Glucose may be mmol/L instead of mg/dL. Convert: mmol/L * 18 = mg/dL. Adjust thresholds: < 2.2 mmol/L (critical low), > 27.8 mmol/L (critical high).
• Hemoglobin may be g/L instead of g/dL. Convert: g/L / 10 = g/dL.
• Always check valueQuantity.unit or valueQuantity.code before comparing to thresholds.

Multiple Specimens for Same Analyte in Scan Window

• A repeated critical value may indicate the first was already addressed and this is a follow-up. Compare timestamps.
• If the second value is improving (moving toward normal), note "trending toward correction" in the alert.
• If the second value is worsening, escalate priority and note "worsening despite intervention."

Related Skills

• lab-result-interpreter -- for comprehensive lab interpretation beyond critical values
• renal-function-dashboard -- for critical electrolytes in the context of renal function staging
• diabetes-panel-review -- for critical glucose values in the context of diabetes management

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