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