Langcare Langcare MCP Fhir Renal Function Dashboard

Renal Function Dashboard

Overview

Pull BUN, creatinine, eGFR, cystatin C, urine protein, urine albumin-to-creatinine ratio, and electrolytes (potassium, calcium, phosphorus, magnesium, bicarbonate). Stage CKD per KDIGO 2024 guidelines using GFR categories (G1-G5) and albuminuria categories (A1-A3). Track eGFR trajectory over time, calculate annual rate of decline, and flag rapid progression. Detect AKI superimposed on CKD. Assess electrolyte management adequacy by CKD stage. Flag medication dose adjustments needed and nephrotoxic drugs.

FHIR Resources Used

Instructions

Step 1: Retrieve Patient Demographics

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

Extract: age, gender, race (from US Core race extension). These are inputs to the CKD-EPI 2021 equation (which removed the race variable) or CKD-EPI cystatin C equation if available.

Step 2: Pull Core Renal Function Labs

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2160-0,3094-0,33914-3,82810-3,76484-0,48642-3,69405-9,14959-1&_sort=-date&_count=50"

LOINC codes:

• 2160-0 = Serum Creatinine
• 3094-0 = BUN (Blood Urea Nitrogen)
• 33914-3 = eGFR by CKD-EPI (creatinine-based)
• 82810-3 = eGFR by CKD-EPI 2021 (without race)
• 76484-0 = eGFR by CKD-EPI cystatin C
• 48642-3 = Urine albumin/creatinine ratio (UACR)
• 69405-9 = Urine albumin/creatinine ratio (alternate)
• 14959-1 = Urine microalbumin

If eGFR not directly available, calculate from creatinine using CKD-EPI 2021:

• eGFR = 142 * min(Scr/kappa, 1)^alpha * max(Scr/kappa, 1)^(-1.200) * 0.9938^age * (1.012 if female)
• kappa = 0.7 (female), 0.9 (male); alpha = -0.241 (female), -0.302 (male)

Step 3: Pull Electrolytes

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2823-3,17861-6,2777-1,19123-9,1963-8,1920-8&_sort=-date&_count=30"

LOINC codes:

• 2823-3 = Potassium
• 17861-6 = Calcium (total)
• 2777-1 = Phosphorus
• 19123-9 = Magnesium
• 1963-8 = Bicarbonate (CO2)
• 1920-8 = AST (for hepatorenal context)

Also pull:

• PTH (2731-8) -- secondary hyperparathyroidism in CKD
• Vitamin D 25-OH (1989-3) -- deficiency common in CKD
• Hemoglobin (718-7) -- anemia of CKD

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2731-8,1989-3,718-7&_sort=-date&_count=10"

Step 4: Stage CKD per KDIGO 2024

GFR Categories:

• G1: eGFR >= 90 (normal or high)
• G2: eGFR 60-89 (mildly decreased)
• G3a: eGFR 45-59 (mildly to moderately decreased)
• G3b: eGFR 30-44 (moderately to severely decreased)
• G4: eGFR 15-29 (severely decreased)
• G5: eGFR < 15 (kidney failure)

Albuminuria Categories:

• A1: UACR < 30 mg/g (normal to mildly increased)
• A2: UACR 30-300 mg/g (moderately increased)
• A3: UACR > 300 mg/g (severely increased)

Prognosis Risk (KDIGO Heat Map):

• Low risk (green): G1A1, G2A1
• Moderately increased risk (yellow): G1A2, G2A2, G3aA1
• High risk (orange): G1A3, G2A3, G3aA2, G3bA1
• Very high risk (red): G3aA3, G3bA2, G3bA3, G4A1, G4A2, G4A3, G5A1, G5A2, G5A3

CKD diagnosis requires GFR < 60 OR albuminuria (UACR >= 30) OR other markers of kidney damage persisting for > 3 months.

Step 5: Track eGFR Trajectory

Pull historical eGFR values (or creatinine to calculate):

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=33914-3,82810-3&_sort=date&_count=20"

Calculate:

• Annual rate of decline: linear regression slope of eGFR over time, expressed as mL/min/1.73m2 per year
• Normal age-related decline: approximately 1 mL/min/1.73m2 per year after age 40
• Rapid decline: > 5 mL/min/1.73m2 per year (KDIGO definition)
• Projected time to eGFR < 15: extrapolate using current trajectory (triggers dialysis planning)

Step 6: Detect AKI Superimposed on CKD

Compare most recent creatinine to baseline (lowest value in past 90 days or known stable value):

KDIGO AKI criteria:

• Stage 1: Creatinine increase >= 0.3 mg/dL within 48 hours OR 1.5-1.9x baseline within 7 days
• Stage 2: Creatinine 2.0-2.9x baseline
• Stage 3: Creatinine >= 3.0x baseline OR creatinine >= 4.0 mg/dL OR initiation of renal replacement therapy

If AKI detected, flag as [AKI ALERT] with stage and recommend: hold nephrotoxic medications, IV fluid assessment, urine output monitoring, nephrology consultation if Stage 2+.

Step 7: Assess Electrolyte Management by CKD Stage

Potassium:

• G1-G3a: target 3.5-5.0 mEq/L (standard)
• G3b-G5: target 3.5-5.5 mEq/L; monitor more frequently
• Flag: > 5.5 (hold ACEi/ARB/spironolactone, dietary counseling); > 6.0 (urgent)

Phosphorus:

• G1-G3a: target 2.5-4.5 mg/dL
• G3b-G5: target 2.5-4.5 mg/dL (maintain within normal range; KDIGO de-emphasizes strict targets)
• Flag: > 4.5 in G3b+: consider phosphate binder, dietary restriction

Calcium:

• Target: 8.5-10.5 mg/dL across all stages
• Correct for albumin: Corrected Ca = total Ca + 0.8 * (4.0 - albumin)
• Flag: < 8.5 with elevated PTH: secondary hyperparathyroidism

Bicarbonate:

• Target: >= 22 mEq/L
• Flag: < 22 in CKD G3-G5: start oral sodium bicarbonate supplementation (slows CKD progression per KDIGO)

PTH:

• G3a-G3b: target within normal range
• G4-G5: target 2-9x upper normal limit (KDIGO)
• Flag: elevated PTH + low vitamin D: correct vitamin D first

Step 8: Check Medications for Renal Dosing

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

Flag medications needing dose adjustment or contraindicated at current eGFR:

• Metformin: reduce dose at eGFR 30-45, contraindicated < 30
• SGLT2 inhibitors: reduced glycemic efficacy < 30 but renal protection continues (per KDIGO/ADA); stop if starting dialysis
• NSAIDs: avoid in eGFR < 30 (relative contraindication in all CKD)
• Gabapentin/pregabalin: dose reduce by eGFR
• Allopurinol: start low dose in CKD
• ACEi/ARB: continue for proteinuria benefit but monitor K+ and creatinine (up to 30% rise in Cr acceptable after initiation)
• Contrast dye: flag if recent or upcoming (hold metformin, hydration protocol)
• Aminoglycosides: avoid or monitor levels closely
• Lithium: narrow therapeutic index, accumulates in renal impairment

See references/renal-medication-dosing.md for complete dosing table.

Step 9: Assess Referral Criteria

Per KDIGO, refer to nephrology if:

• eGFR < 30 (G4-G5)
• UACR > 300 mg/g (A3) persistent
• Rapid decline (> 5 mL/min/1.73m2 per year)
• AKI or unexplained acute decline
• Refractory hypertension (>= 4 agents)
• Persistent electrolyte abnormalities (hyperkalemia, metabolic acidosis)
• Hereditary kidney disease suspected

Dialysis planning discussion recommended when eGFR < 20 (projected to reach < 15 within 12 months).

Step 10: Format Output

RENAL FUNCTION DASHBOARD -- [Patient Name] ([Age][Sex])
========================================================
CKD STAGING (KDIGO 2024)
========================
GFR Category:         G[stage] (eGFR [value] mL/min/1.73m2)
Albuminuria Category: A[stage] (UACR [value] mg/g)
Overall Risk:         [Low / Moderate / High / Very High]
AKI Status:           [None detected / AKI Stage X]

eGFR TRAJECTORY
===============
[date1]: [eGFR1]
[date2]: [eGFR2]
[date3]: [eGFR3]
[date4]: [eGFR4]
Annual rate of decline: [value] mL/min/1.73m2/year [STABLE / RAPID DECLINE]
Projected eGFR < 15:   [estimated date or "Not projected within 5 years"]

CORE RENAL LABS
===============
Creatinine:   [value] mg/dL  ([date])  Baseline: [value]
BUN:          [value] mg/dL  ([date])
BUN/Cr ratio: [calculated]
eGFR:         [value]        ([date])
Cystatin C:   [value] mg/L   ([date])  [if available]
UACR:         [value] mg/g   ([date])

ELECTROLYTES & MINERAL BONE
============================
Potassium:    [value] mEq/L  [target for CKD stage]  [NORMAL / FLAG]
Calcium:      [value] mg/dL  (corrected: [value])     [NORMAL / FLAG]
Phosphorus:   [value] mg/dL  [target for CKD stage]  [NORMAL / FLAG]
Magnesium:    [value] mg/dL                           [NORMAL / FLAG]
Bicarbonate:  [value] mEq/L  (target >= 22)          [NORMAL / LOW]
PTH:          [value] pg/mL  [target for CKD stage]  [NORMAL / ELEVATED]
Vitamin D:    [value] ng/mL                           [NORMAL / DEFICIENT]
Hemoglobin:   [value] g/dL                            [NORMAL / ANEMIA]

MEDICATION REVIEW
=================
[drug]: [current dose] -- [appropriate / ADJUST to X / DISCONTINUE]
[drug]: [current dose] -- [appropriate / ADJUST to X / DISCONTINUE]

NEPHROTOXIC MEDICATIONS: [list or "None identified"]

RECOMMENDATIONS
===============
1. [CKD management recommendation]
2. [Electrolyte management]
3. [Medication adjustment]
4. [Referral if indicated]
5. [Next monitoring interval]

Examples

Example 1: Stable CKD Stage 3a

User says: "Check kidney function for patient 9920"

Actions:

1. fhir_read Patient/9920 -- 64-year-old female
2. fhir_search Observation?patient=9920&code=2160-0,3094-0,33914-3,48642-3&_sort=-date&_count=50 -- Cr 1.3, BUN 24, eGFR 52, UACR 45 mg/g
3. fhir_search Observation?patient=9920&code=33914-3,82810-3&_sort=date&_count=20 -- eGFR over 2 years: 58, 56, 54, 53, 52
4. fhir_search Observation?patient=9920&code=2823-3,17861-6,2777-1,19123-9,1963-8&_sort=-date&_count=30 -- K 4.6, Ca 9.2, Phos 3.8, Mg 2.0, Bicarb 23
5. fhir_search Observation?patient=9920&code=2731-8,1989-3,718-7&_sort=-date&_count=10 -- PTH 68, Vit D 28, Hgb 12.1
6. fhir_search MedicationStatement?patient=9920&status=active -- lisinopril, metformin 1000mg BID, atorvastatin
7. fhir_search Condition?patient=9920&clinical-status=active -- Type 2 DM, HTN, CKD stage 3

Result: CKD G3a/A2, high risk (orange on KDIGO heat map). eGFR declining at 3 mL/min/year (not yet rapid but above age-related). UACR 45 (moderately increased). Electrolytes well-managed. PTH mildly elevated but Vitamin D borderline -- supplement to > 30 ng/mL. Metformin dose appropriate at eGFR 52 (reduce if eGFR drops below 45). ACEi appropriate for albuminuria. Consider adding SGLT2 inhibitor for renal protection. Next monitoring: 3-6 months.

Example 2: Rapid Decline With AKI

User says: "Renal panel for patient r-5501, creatinine has been going up"

Actions:

1. fhir_read Patient/r-5501 -- 73-year-old male
2. fhir_search Observation?patient=r-5501&code=2160-0&_sort=-date&_count=10 -- Cr values: 3.8 (today), 2.1 (1 week ago), 1.8 (1 month ago), 1.6 (3 months ago), 1.5 (6 months ago)
3. fhir_search Observation?patient=r-5501&code=33914-3&_sort=date&_count=20 -- eGFR: 42, 38, 34, 28, 14 (calculated from Cr)
4. fhir_search Observation?patient=r-5501&code=2823-3&_sort=-date&_count=5 -- K 5.9 mEq/L
5. fhir_search MedicationStatement?patient=r-5501&status=active -- ibuprofen 600mg TID, lisinopril, metformin
6. fhir_search Condition?patient=r-5501&clinical-status=active -- CKD stage 3b, DM2, OA

Result:

[AKI ALERT] Stage 2 superimposed on CKD
Creatinine 3.8 mg/dL = 2.1x baseline (1.8), rise of 1.7 mg/dL in 1 week
eGFR dropped from 34 to 14 -- now G5 territory
Baseline trajectory was already rapid: 8 mL/min/year decline over 6 months

URGENT ACTIONS:
1. STOP ibuprofen immediately (nephrotoxic, primary suspect for acute decline)
2. HOLD metformin (eGFR < 30, lactic acidosis risk)
3. HOLD lisinopril (hyperkalemia K 5.9, AKI)
4. Potassium 5.9: ECG stat, consider calcium gluconate, kayexalate
5. Nephrology consult STAT
6. IV fluid assessment, urine output monitoring
7. Renal ultrasound to rule out obstruction

Troubleshooting

eGFR Not Available as a Separate Observation

• Calculate from serum creatinine using CKD-EPI 2021 equation if Observation for LOINC 33914-3 or 82810-3 is absent. Requires: creatinine value, age, sex.
• Some systems report eGFR as a component of a renal panel Observation. Check component array on BMP/CMP panel Observations.

UACR Reported as Separate Urine Albumin and Urine Creatinine

• Pull urine albumin (14959-1) and urine creatinine (2161-8) separately. Calculate UACR = urine albumin (mg/L) / urine creatinine (g/L). Ensure unit conversion: if urine creatinine is in mg/dL, convert to g/L by dividing by 100.
• If only urine protein (2888-6) is available (not albumin-specific), use protein/creatinine ratio as a surrogate. UPCR > 0.5 g/g approximates UACR > 300 mg/g.

Historical eGFR Values Use Different Equations

• Older labs may use MDRD instead of CKD-EPI, or may include the race coefficient. For trend analysis, recalculate all values using CKD-EPI 2021 (without race) from stored creatinine values for consistency.
• Note in the trajectory: "eGFR values recalculated using CKD-EPI 2021 for consistency."

Related Skills

• lab-result-interpreter -- for comprehensive interpretation of all lab results beyond renal
• diabetes-panel-review -- for diabetic nephropathy in the context of full diabetes management
• critical-value-alert-generator -- for critical electrolyte values in renal failure
• preoperative-lab-checklist -- for renal function assessment before surgery

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