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DRAFT - Pending Review
This plan requires physician review before clinical use.

Giant Cell Arteritis (GCA)

VERSION: 1.2 CREATED: January 30, 2026 STATUS: Draft - Pending Review


DIAGNOSIS: Giant Cell Arteritis (GCA)

ICD-10: M31.6 (Other giant cell arteritis), M31.5 (Giant cell arteritis with polymyalgia rheumatica)

SYNONYMS: Giant cell arteritis, GCA, temporal arteritis, cranial arteritis, Horton disease, granulomatous arteritis, large-vessel vasculitis, polymyalgia rheumatica-associated vasculitis

SCOPE: Urgent diagnostic workup, empiric glucocorticoid treatment, and long-term management of giant cell arteritis. Covers cranial GCA (visual, neurologic), large-vessel GCA, overlap with polymyalgia rheumatica (PMR), vision-threatening presentations, steroid-sparing therapy, and disease monitoring. For isolated PMR without GCA features, GCA workup should still be considered. For other vasculitides (CNS vasculitis, PAN), use separate templates.


PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

═══════════════════════════════════════════════════════════ SECTION A: ACTION ITEMS ═══════════════════════════════════════════════════════════

1. LABORATORY WORKUP

1A. Essential/Core Labs

Test Rationale Target Finding ED HOSP OPD ICU
ESR (Westergren) (CPT 85652) Elevated in >90% GCA; ESR >50 mm/hr supports diagnosis (ACR criteria); sensitivity ~80-90% Elevated (>50 mm/hr typical; often >80-100) STAT STAT ROUTINE STAT
CRP (CPT 86140) More sensitive than ESR alone; elevated in ~95% GCA; combined ESR+CRP sensitivity >99% Elevated (>2.5 mg/dL typical) STAT STAT ROUTINE STAT
CBC with differential (CPT 85025) Normocytic anemia of chronic disease; thrombocytosis (reactive); baseline before steroids Mild anemia; thrombocytosis; leukocytosis STAT STAT ROUTINE STAT
CMP (BMP + LFTs) (CPT 80053) Baseline before steroids; elevated alkaline phosphatase (hepatic involvement in ~30%) Elevated alkaline phosphatase; otherwise normal STAT STAT ROUTINE STAT
Blood glucose (CPT 82947) Pre-steroid baseline Normal STAT STAT ROUTINE STAT
HbA1c (CPT 83036) Glycemic status before long-term steroids <5.7% (document baseline for steroid-induced diabetes monitoring) - ROUTINE ROUTINE -
Albumin (CPT 82040) Nutritional status; inflammation marker May be low (acute phase reactant) URGENT ROUTINE ROUTINE URGENT
Fibrinogen (CPT 85384) Acute phase reactant; may be elevated Elevated URGENT ROUTINE ROUTINE URGENT
Ferritin (CPT 82728) Acute phase reactant; anemia workup May be elevated - ROUTINE ROUTINE -
PT/INR, aPTT (CPT 85610+85730) Baseline coagulation; pre-procedure (biopsy) Normal STAT STAT - STAT
Urinalysis (CPT 81003) Renal vasculitis screen; baseline Normal URGENT ROUTINE ROUTINE URGENT
TSH (CPT 84443) Thyroid disease comorbidity Normal - ROUTINE ROUTINE -
Lipid panel (CPT 80061) Cardiovascular risk assessment; steroid effects on lipids Document baseline - ROUTINE ROUTINE -

1B. Extended Workup

Test Rationale Target Finding ED HOSP OPD ICU
ANA (CPT 86235) Other vasculitis/connective tissue disease screen Negative - ROUTINE ROUTINE -
ANCA (c-ANCA/PR3 and p-ANCA/MPO) (CPT 86235+86200) GPA (Wegener) or MPA vasculitis mimic Negative - ROUTINE ROUTINE -
Hepatitis B and C serologies (CPT 87340+86803) Hepatitis-associated vasculitis; pre-immunosuppression Negative - ROUTINE ROUTINE -
Quantiferon-TB Gold (CPT 86480) Pre-immunosuppression screen; granulomatous disease differential Negative - ROUTINE ROUTINE -
Serum protein electrophoresis (SPEP) (CPT 86334) Monoclonal gammopathy/myeloma (elevated ESR differential) Normal - ROUTINE ROUTINE -
IL-6 level (CPT 83519) Elevated in GCA; potential biomarker for monitoring (especially on tocilizumab where ESR/CRP are suppressed) Elevated - ROUTINE ROUTINE -
Vitamin D 25-OH (CPT 82306) Baseline before long-term steroids (bone health) >30 ng/mL; supplement if deficient - ROUTINE ROUTINE -
DEXA scan baseline referral (CPT 77080) Bone density before anticipated chronic steroid use T-score >-2.5 - - ROUTINE -
Complement C3, C4 (CPT 86160+86162) Complement-mediated vasculitis screen Normal - ROUTINE ROUTINE -

Note: Normal ESR does NOT exclude GCA -- approximately 4-10% of biopsy-proven GCA has normal ESR. Always obtain BOTH ESR and CRP. A normal ESR with normal CRP has very high negative predictive value but still does not fully exclude GCA if clinical suspicion is high.

1C. Rare/Specialized (Refractory or Atypical)

Test Rationale Target Finding ED HOSP OPD ICU
Anti-GBM antibody If pulmonary-renal syndrome suspected Negative - EXT EXT -
Cryoglobulins (CPT 82595) Cryoglobulinemic vasculitis mimic Negative - EXT EXT -
ACE level (CPT 82164) Sarcoidosis (granulomatous disease differential) Normal - EXT EXT -
IgG4 level IgG4-related disease (pachymeningitis, aortitis mimic) Normal (<135 mg/dL) - EXT EXT -

2. DIAGNOSTIC IMAGING & STUDIES

2A. Essential/First-line

Study Timing Target Finding Contraindications ED HOSP OPD ICU
Temporal artery ultrasound (halo sign) (CPT 93880) Within 24h (before or within days of starting steroids; halo fades after ~2 weeks on steroids) Halo sign (hypoechoic wall thickening); compression sign; stenosis/occlusion; sensitivity ~77%, specificity ~96% None significant; operator-dependent URGENT URGENT ROUTINE URGENT
Temporal artery biopsy (CPT 37609) Within 1-2 weeks of starting steroids (biopsy remains positive for 2-6 weeks on steroids; do NOT delay steroids for biopsy) Granulomatous inflammation with multinucleated giant cells; intimal hyperplasia; fragmented internal elastic lamina; sensitivity ~85% (bilateral increases to ~90%) Anticoagulation (relative); infection at site - URGENT ROUTINE -
CT head without contrast (CPT 70450) Immediate if acute neurologic symptoms Rule out stroke, hemorrhage, mass None significant STAT STAT - STAT
MRI brain with and without contrast (CPT 70553) If stroke symptoms or cranial nerve palsy Acute infarction (vertebrobasilar territory more common); cranial nerve enhancement; pachymeningeal thickening Standard MRI contraindications URGENT URGENT ROUTINE URGENT
Ophthalmologic examination (fundoscopy, visual acuity, visual fields, relative afferent pupillary defect) STAT if visual symptoms Anterior ischemic optic neuropathy (AION): pale swollen disc; cherry-red spot (CRAO); visual field defects None STAT STAT ROUTINE STAT

2B. Extended

Study Timing Target Finding Contraindications ED HOSP OPD ICU
CT angiography of aorta and branches (CTA) (CPT 71275) Within 1-2 weeks; assess for large-vessel GCA Aortic wall thickening; stenosis of subclavian, axillary arteries; aortitis Contrast allergy; renal insufficiency - ROUTINE ROUTINE -
MR angiography of aorta and branches (MRA) Within 1-2 weeks; alternative to CTA for large-vessel assessment Vessel wall thickening and enhancement (mural inflammation); stenosis MRI contraindications - ROUTINE ROUTINE -
FDG-PET/CT (CPT 78816) If large-vessel GCA suspected; assessment of disease extent; monitor treatment response Increased FDG uptake in aorta and large-vessel walls (vascular inflammation) Uncontrolled diabetes; pregnancy - ROUTINE ROUTINE -
Fluorescein angiography If retinal artery occlusion suspected Delayed choroidal filling; optic disc hypoperfusion Fluorescein allergy - URGENT ROUTINE -
Carotid Doppler ultrasound (CPT 93880) If carotid territory symptoms Stenosis; wall thickening None significant - ROUTINE ROUTINE -

2C. Rare/Specialized

Study Timing Target Finding Contraindications ED HOSP OPD ICU
Contrast-enhanced MRI of temporal arteries (vessel wall imaging) If biopsy equivocal or declined; alternative to US in some centers Mural enhancement and thickening of temporal arteries MRI contraindications - EXT EXT -
Aortic echocardiogram (TTE/TEE) If aortic regurgitation or aortitis suspected Aortic root dilation; aortic regurgitation; wall thickening TEE: esophageal pathology - ROUTINE ROUTINE -
Contralateral temporal artery biopsy If initial biopsy negative but clinical suspicion remains high Contralateral biopsy increases sensitivity to ~90% (skip lesions) Same as initial biopsy - EXT EXT -

3. TREATMENT

3A. Acute/Emergent (Vision-Threatening GCA)

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Methylprednisolone IV pulse (vision-threatening) IV Visual symptoms: acute vision loss, amaurosis fugax, diplopia, AION, CRAO, cranial nerve palsy 1000 mg :: IV :: daily x 3 days :: 1000 mg IV daily for 3 days (some protocols use 500 mg-1000 mg); infuse over 1-2 hours; then transition to oral prednisone 1 mg/kg/day Active untreated infection; uncontrolled diabetes; psychosis from steroids Glucose q6h (target <180); BP; mood; electrolytes; GI prophylaxis STAT STAT - STAT
Aspirin (low-dose) PO Antiplatelet therapy to reduce ischemic complications (visual loss, stroke) in GCA 81 mg daily :: PO :: daily :: 81 mg PO daily Active GI bleeding; aspirin allergy; concurrent anticoagulation (relative) GI symptoms; bleeding signs STAT STAT ROUTINE STAT
Omeprazole (GI prophylaxis) PO/IV GI protection during high-dose steroids + aspirin 40 mg daily :: PO :: daily :: 40 mg PO/IV daily while on steroids PPI allergy None routine STAT STAT ROUTINE STAT

Note: VISUAL SYMPTOMS ARE A MEDICAL EMERGENCY. Start IV methylprednisolone IMMEDIATELY -- do NOT wait for biopsy, lab results, or imaging. Vision loss in GCA is often irreversible if untreated. The goal is to prevent vision loss in the fellow eye (bilateral involvement occurs in ~25-50% within days without treatment). If the patient can take oral medications and has no vision-threatening symptoms, oral prednisone can be started directly.

3B. Standard Oral Glucocorticoid Treatment (Non-Vision-Threatening)

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Prednisone (initial high-dose) PO GCA without visual symptoms; after IV pulse for vision-threatening GCA 1 mg/kg :: PO :: daily :: 1 mg/kg/day PO (max 60 mg); take in morning with food; maintain initial dose 2-4 weeks until symptoms resolve and ESR/CRP normalize Active untreated infection; poorly controlled diabetes Glucose; BP; weight; mood; bone density; cataracts; adrenal function STAT STAT ROUTINE STAT
Prednisone (taper phase 1: 40 mg → 20 mg) PO After 2-4 weeks at initial dose with symptom resolution 40 mg :: PO :: daily :: Reduce by 5-10 mg every 2 weeks from 40 mg to 20 mg; monitor symptoms and ESR/CRP at each step Same as above ESR/CRP at each taper step; symptom recurrence - ROUTINE ROUTINE -
Prednisone (taper phase 2: 20 mg → 10 mg) PO Continued improvement; normal inflammatory markers 20 mg :: PO :: daily :: Reduce by 2.5 mg every 2-4 weeks from 20 mg to 10 mg; slower taper reduces relapse risk Same as above ESR/CRP; symptoms; adrenal function assessment - - ROUTINE -
Prednisone (taper phase 3: 10 mg → off) PO Near-remission; on steroid-sparing agent if available 10 mg :: PO :: daily :: Reduce by 1 mg every month from 10 mg to off; total steroid duration typically 12-24 months; some patients require low-dose indefinitely Adrenal insufficiency risk on discontinuation Morning cortisol if dose <7.5 mg; ACTH stimulation test before complete discontinuation; ESR/CRP - - ROUTINE -
Calcium + Vitamin D (bone protection) PO All patients on chronic steroids 1000 mg Ca + 2000 IU Vit D :: PO :: daily :: Calcium 1000-1200 mg/day + Vitamin D 2000-4000 IU/day (target 25-OH >30 ng/mL) Hypercalcemia; kidney stones 25-OH Vitamin D level; calcium; DEXA at baseline and annually - ROUTINE ROUTINE -
Alendronate (bisphosphonate for osteoporosis prevention) PO Steroids anticipated >3 months; T-score ≤-1.0 70 mg weekly :: PO :: weekly :: 70 mg PO weekly; take on empty stomach with 8 oz water; remain upright 30 min Esophageal disorders; CrCl <35; hypocalcemia DEXA q1-2 years; dental health (osteonecrosis of jaw); esophageal symptoms - - ROUTINE -

Note: Typical steroid taper duration is 12-24 months. Relapse rate on taper is ~50%. Most relapses occur when prednisone dose is below 10-15 mg or within 1 year of discontinuation. Monitor ESR/CRP at each taper step -- rising markers may herald relapse. Cumulative steroid toxicity is the major long-term concern (osteoporosis, diabetes, cataracts, infections, weight gain, skin fragility).

3C. Steroid-Sparing Therapy

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Tocilizumab (Actemra) SC FDA-approved steroid-sparing agent for GCA (GiACTA trial); reduces relapse rate and steroid exposure 162 mg :: SC :: weekly :: 162 mg SC weekly (preferred) or every 2 weeks; self-injectable; can also use 8 mg/kg IV q4wk Active infection; hepatic impairment (ALT >5x ULN); diverticulitis; concurrent live vaccines; ANC <2000; platelets <100K CBC q4-8 weeks; LFTs q4-8 weeks; lipid panel q3 months; infection surveillance; GI perforation risk; neutropenia; NOTE: tocilizumab suppresses ESR/CRP -- cannot use these for disease monitoring (use IL-6 or clinical assessment instead) - - ROUTINE -
Methotrexate PO Steroid-sparing alternative (weaker evidence than tocilizumab); relapse prevention 7.5 mg :: PO :: weekly :: Start 7.5-10 mg PO weekly; titrate to 15-25 mg/week; take with folic acid 1 mg daily (except MTX day) Pregnancy; hepatic disease; CrCl <30; active infection; interstitial lung disease CBC q2-4 weeks initially, then q1-3 months; LFTs q1-3 months; CrCl; pulmonary symptoms (pneumonitis); folate supplementation - - ROUTINE -
Folic acid (with methotrexate) PO Reduce methotrexate side effects (stomatitis, cytopenias) 1 mg daily :: PO :: daily :: 1 mg PO daily (skip day of MTX) None significant None routine - - ROUTINE -
Leflunomide PO Alternative steroid-sparing if MTX intolerant (limited evidence) 10-20 mg daily :: PO :: daily :: 10-20 mg PO daily Pregnancy (Category X); hepatic disease CBC; LFTs monthly x 6 months, then q1-3 months; BP; diarrhea - - EXT -

Note: Tocilizumab (GiACTA trial, 2017) is the only FDA-approved steroid-sparing agent for GCA. It significantly reduces relapse rate and allows faster steroid taper. IMPORTANT: Tocilizumab suppresses ESR and CRP, making these markers unreliable for disease monitoring -- use clinical assessment and IL-6 levels instead. Methotrexate has mixed trial data (3 RCTs with conflicting results) but is commonly used as a cheaper alternative. Consider steroid-sparing therapy for all GCA patients to reduce cumulative steroid toxicity.

3D. Symptomatic Treatments

Treatment Route Indication Dosing Contraindications Monitoring ED HOSP OPD ICU
Acetaminophen PO Headache management; scalp tenderness 1000 mg :: PO :: q6h PRN :: 1000 mg PO q6h PRN; max 3g/day Hepatic impairment LFTs if chronic use STAT STAT ROUTINE STAT
Trazodone PO Steroid-induced insomnia 25-50 mg qHS :: PO :: qHS :: 25-50 mg PO qHS; max 100 mg Concurrent MAOIs; QTc prolongation Orthostatic hypotension; sedation - ROUTINE ROUTINE -
Insulin (steroid-induced diabetes) SC Steroid-induced hyperglycemia not controlled with oral agents Per protocol :: SC :: PRN :: Per endocrine protocol; anticipate afternoon/evening hyperglycemia pattern with morning steroid dosing Hypoglycemia risk Glucose QID; HbA1c q3 months - ROUTINE ROUTINE -
Trimethoprim-sulfamethoxazole (PJP prophylaxis) PO PJP prophylaxis if on ≥20 mg prednisone for >4 weeks with additional immunosuppression 1 DS tablet :: PO :: 3x/week :: 1 DS tablet PO Monday/Wednesday/Friday Sulfonamide allergy; renal impairment; hyperkalemia CBC; renal function; electrolytes - ROUTINE ROUTINE -

4. OTHER RECOMMENDATIONS

4A. Referrals & Consults

Recommendation ED HOSP OPD ICU
Ophthalmology/neuro-ophthalmology for URGENT visual assessment (fundoscopy, visual fields, fluorescein angiography) if any visual symptoms STAT STAT URGENT STAT
Rheumatology for long-term GCA management, steroid-sparing therapy initiation, and disease monitoring - URGENT ROUTINE -
Vascular surgery for temporal artery biopsy (do NOT delay steroids while awaiting biopsy) - URGENT ROUTINE -
Endocrinology for steroid-induced diabetes management if persistent hyperglycemia - ROUTINE ROUTINE -
Neurology if stroke symptoms, cranial nerve palsy, or CNS vasculitis suspected STAT STAT ROUTINE STAT
Cardiology/vascular surgery if aortitis with aneurysm or significant large-vessel stenosis identified - ROUTINE ROUTINE -
Physical therapy for PMR-associated weakness and deconditioning - ROUTINE ROUTINE -
Social work for steroid side effect management support and medication cost assistance (tocilizumab is expensive) - ROUTINE ROUTINE -
Nutrition/dietitian for weight management and diabetes prevention during chronic steroid use - ROUTINE ROUTINE -

4B. Patient Instructions

Recommendation ED HOSP OPD
Return to ED IMMEDIATELY for any new or worsening vision changes (blurred vision, double vision, vision loss, shadows) -- this is a vision-threatening emergency requiring immediate treatment Y Y Y
Report new headache, jaw pain while chewing, scalp tenderness, or limb claudication as these may indicate disease relapse - Y Y
Do NOT stop prednisone abruptly -- sudden discontinuation can cause adrenal crisis and disease flare - Y Y
Take prednisone in the morning with food to minimize insomnia and GI upset - Y Y
Monitor blood glucose as directed; report persistent readings >200 mg/dL - Y Y
Report signs of infection (fever >100.4F, cough, dysuria) promptly as steroids increase infection risk - Y Y
Attend all follow-up appointments for blood work (ESR/CRP monitoring guides treatment) - Y Y
Do NOT miss tocilizumab injections if prescribed; medication adherence prevents relapse - Y Y
Weight-bearing exercise 30 minutes daily to maintain bone density and muscle strength on steroids - Y Y
Annual ophthalmology exam for steroid-induced cataract and glaucoma screening - Y Y

4C. Lifestyle & Prevention

Recommendation ED HOSP OPD
Calcium 1000-1200 mg/day + Vitamin D 2000-4000 IU daily for bone protection during steroid use - Y Y
Low-sodium, diabetic-friendly diet to mitigate steroid-induced weight gain, edema, and hyperglycemia - Y Y
Smoking cessation to reduce vascular inflammation and cardiovascular risk - Y Y
Annual influenza vaccine; pneumococcal and shingles (Shingrix) vaccination before immunosuppression - Y Y
Avoid live vaccines while on immunosuppressive therapy - Y Y
Stress management and adequate sleep to support immune function and reduce steroid side effects - Y Y
Fall prevention measures (steroid myopathy increases fall risk; bone fragility increases fracture risk) - Y Y

═══════════════════════════════════════════════════════════ SECTION B: REFERENCE (Expand as Needed) ═══════════════════════════════════════════════════════════

5. DIFFERENTIAL DIAGNOSIS

Alternative Diagnosis Key Distinguishing Features Tests to Differentiate
Non-arteritic anterior ischemic optic neuropathy (NAION) Younger patients possible; no systemic inflammation; "disc at risk" (small C/D ratio); no jaw claudication or scalp tenderness Normal ESR/CRP; no temporal artery abnormality on US; no biopsy inflammation
Migraine / tension-type headache Recurrent pattern; no systemic inflammation; no visual loss (aura resolves) Normal ESR/CRP; normal temporal artery exam
Trigeminal neuralgia Lancinating pain in V2/V3 distribution; triggered by touch/chewing; no inflammation Normal ESR/CRP; MRI for vascular loop
TMJ dysfunction Jaw pain with chewing; tenderness over TMJ; click/pop; bilateral possible Normal ESR/CRP; dental/TMJ evaluation
Polymyalgia rheumatica (without GCA) Proximal myalgias; morning stiffness; elevated ESR/CRP; NO headache, visual symptoms, or jaw claudication Consider GCA workup if inflammatory markers very high or headache develops; lower steroid dose (15-20 mg) sufficient
Other vasculitis (CNS vasculitis, PAN, GPA) Different vessel size involvement; different organ patterns; ANCA may be positive ANCA; angiography; tissue biopsy; specific clinical features
Atherosclerotic disease (carotid stenosis, vertebrobasilar disease) Cardiovascular risk factors; arterial territory symptoms; no systemic inflammation Normal ESR/CRP; carotid Doppler/CTA; different vascular territory
Multiple myeloma / Waldenstrom Elevated ESR from paraprotein; no temporal artery symptoms; bone pain; hyperviscosity SPEP/UPEP; bone marrow biopsy; immunofixation
Infection (endocarditis, osteomyelitis, TB) Fever; positive cultures; specific organ involvement Blood cultures; site-specific imaging; cultures
Lymphoma / malignancy B-symptoms; lymphadenopathy; elevated ESR from inflammation CT chest/abd/pelvis; biopsy; LDH
IgG4-related disease Multi-organ fibroinflammatory disease; aortitis; elevated IgG4; responds to rituximab IgG4 level; tissue biopsy (IgG4+ plasma cells); different histology
Takayasu arteritis Large-vessel vasculitis in young women (<40); claudication; absent pulses Age of onset; angiography pattern; no giant cells on temporal artery
Fibromyalgia Widespread pain; fatigue; no inflammation Normal ESR/CRP; tender points; no objective inflammation

6. MONITORING PARAMETERS

Parameter Frequency Target/Threshold Action if Abnormal ED HOSP OPD ICU
ESR (CPT 85652) Weekly x 4 weeks; then q2 weeks during taper; then monthly; then q3 months Normalizing (<30 mm/hr); stable Rising ESR: evaluate for relapse; consider holding taper or increasing dose STAT STAT ROUTINE STAT
CRP (CPT 86140) Same schedule as ESR Normalizing (<0.5 mg/dL) Rising CRP: same as ESR; CRP normalizes faster and is more responsive to disease activity STAT STAT ROUTINE STAT
Visual acuity and visual fields Daily (inpatient) if visual symptoms; each OPD visit initially; then q3 months Stable or improving Any deterioration: urgent ophthalmology; consider IV steroids; escalate therapy STAT STAT ROUTINE STAT
Blood glucose Q6h during IV steroids; daily during high-dose oral; fasting at OPD visits <180 mg/dL inpatient; FBG <126 outpatient Insulin if needed; endocrine referral if HbA1c >7% STAT STAT ROUTINE STAT
HbA1c Baseline; q3 months on steroids <7% Diabetes management escalation; endocrine referral - ROUTINE ROUTINE -
Blood pressure Q4h (inpatient); each OPD visit <140/90 (or <130/80 if diabetes) Antihypertensive initiation/adjustment STAT STAT ROUTINE STAT
Weight Each OPD visit Stable; <5% gain from baseline Dietary counseling; exercise prescription - ROUTINE ROUTINE -
Bone density (DEXA) Baseline; q1-2 years on steroids T-score >-2.5 Bisphosphonate; calcium/vitamin D optimization - - ROUTINE -
CBC q1-3 months (more frequent if on methotrexate/tocilizumab) Normal ranges Dose adjustment of steroid-sparing agent; infection evaluation if leukopenia - ROUTINE ROUTINE -
LFTs q1-3 months (especially on methotrexate/tocilizumab) ALT/AST <3x ULN Dose reduction or agent switch - ROUTINE ROUTINE -
Lipid panel q3-6 months on tocilizumab; annually on steroids LDL <100 Statin therapy if indicated - - ROUTINE -
GCA symptom checklist (headache, jaw claudication, scalp tenderness, PMR symptoms, visual symptoms) Each visit Symptom-free If symptoms recur: increase steroid dose to last effective dose; re-evaluate with ESR/CRP - ROUTINE ROUTINE -
Aortic imaging (CTA or MRA) Baseline if large-vessel involvement; then q1-2 years No progression; no aneurysm Vascular surgery referral if aneurysm >5 cm or rapidly expanding - ROUTINE ROUTINE -
Ophthalmologic exam (cataracts, glaucoma) Annually while on chronic steroids Normal IOP; no cataracts Ophthalmology management; IOP-lowering drops if elevated - - ROUTINE -

7. DISPOSITION CRITERIA

Disposition Criteria
Discharge home No visual symptoms or stable/improving vision; oral steroids initiated; able to tolerate oral medication; outpatient biopsy arranged; follow-up with rheumatology/ophthalmology within 1 week; patient educated on visual warning signs
Admit to floor Acute vision loss or amaurosis fugax requiring IV methylprednisolone; new stroke symptoms; unable to tolerate oral steroids; significant steroid complications (severe hyperglycemia, psychosis); diagnostic uncertainty requiring expedited workup
Admit to ICU Acute stroke with neurologic emergency; aortic dissection from aortitis; severe steroid complications requiring ICU monitoring; rare: severe systemic vasculitis with multiorgan involvement
Transfer to higher level of care Neuro-ophthalmology or temporal artery biopsy not available; stroke requiring neurointerventional capability not available at current facility
Outpatient follow-up All patients: rheumatology within 1-2 weeks; ophthalmology/neuro-ophthalmology within 1-2 weeks; PCP within 2-4 weeks (steroid monitoring); labs (ESR/CRP) at 1 week, then q2 weeks during initial taper
Readmission criteria New visual symptoms (any); disease flare with headache/jaw claudication and rising ESR/CRP; severe steroid complications (psychosis, GI bleeding, severe hyperglycemia, infection)

8. EVIDENCE & REFERENCES

Recommendation Evidence Level Source
ACR 1990 classification criteria for GCA Expert Consensus Hunder GG et al. Arthritis Rheum 1990;33:1122-1128
ACR/EULAR 2022 classification criteria for GCA Expert Consensus Ponte C et al. Ann Rheum Dis 2022;81:1647-1653
GiACTA trial: tocilizumab for GCA (FDA approval) Class I (RCT) Stone JH et al. N Engl J Med 2017;377:317-328
Temporal artery ultrasound halo sign (TABUL study) Class II Luqmani R et al. Health Technol Assess 2016;20:1-238
Fast-track pathway for GCA diagnosis reduces vision loss Class III Diamantopoulos AP et al. Ann Rheum Dis 2016;75:1961-1964
IV methylprednisolone for vision-threatening GCA Class III, Expert Consensus Hayreh SS et al. Ophthalmology 2002;109:1757-1765
Low-dose aspirin reduces ischemic complications in GCA Class III Nesher G et al. Arthritis Rheum 2004;50:1332-1337
Biopsy sensitivity: unilateral ~85%, bilateral ~90% Class II Breuer GS et al. Isr Med Assoc J 2013;15:756-760
Biopsy remains positive for 2-6 weeks after starting steroids Class III Achkar AA et al. Ann Intern Med 1994;120:987-992
GCA relapse rate on steroid taper (~50%) Class II Martinez-Lado L et al. Semin Arthritis Rheum 2011;41:252-263
ESR normal in ~4-10% of biopsy-proven GCA Class III Parikh M et al. Clin Exp Rheumatol 2006;24(2 Suppl 41):S35-40
Large-vessel GCA involvement (~50% on PET/CT) Class II Blockmans D et al. Rheumatology 2006;45:432-437
Aortic aneurysm risk in GCA (17x increased) Class II Evans JM et al. Ann Intern Med 1995;122:502-507
Tocilizumab suppresses ESR/CRP; cannot use for monitoring Class II Stone JH et al. N Engl J Med 2017
Methotrexate as steroid-sparing in GCA (mixed evidence) Class I (3 RCTs) Mahr AD et al. Arthritis Rheum 2007;56:2789-2797
FDG-PET for large-vessel GCA diagnosis and monitoring Class II Dejaco C et al. Ann Rheum Dis 2018;77:636-643
BSR/BHPR guidelines for management of GCA Expert Consensus Mackie SL et al. Rheumatology 2020;59:e1-e23

CLINICAL DECISION SUPPORT NOTES

ACR 1990 Classification Criteria (≥3 of 5 = GCA)

  1. Age at disease onset ≥50 years
  2. New headache (new onset or new type)
  3. Temporal artery abnormality (tenderness or reduced pulse)
  4. Elevated ESR ≥50 mm/hr (Westergren)
  5. Abnormal artery biopsy (granulomatous inflammation with giant cells)

Sensitivity 93.5%, specificity 91.2%

GCA Clinical Presentations

Presentation Frequency Key Features
Cranial GCA (classic) ~70% Headache, jaw claudication, scalp tenderness, temporal artery tenderness
Ophthalmic GCA ~15-20% AION (most common cause of GCA vision loss); CRAO; diplopia; amaurosis fugax
Large-vessel GCA ~50% (often subclinical) Upper extremity claudication; aortitis; subclavian/axillary stenosis
PMR overlap ~40-60% Proximal myalgias (shoulders, hips); morning stiffness >1 hour; elevated ESR
Constitutional only ~15% Fever of unknown origin; weight loss; malaise; elevated ESR

Vision Loss Prevention Pathway

Suspected GCA with ANY visual symptom
  ↓
STAT ophthalmology exam + STAT ESR/CRP
  ↓
START IV methylprednisolone 1000 mg IMMEDIATELY (do NOT wait for labs or biopsy)
  ↓
Temporal artery ultrasound within 24h
  ↓
Temporal artery biopsy within 1-2 weeks (remains positive on steroids)
  ↓
After 3 days IV steroids → oral prednisone 1 mg/kg/day
  ↓
Monitor visual acuity daily until stable

Steroid Taper Schedule (Approximate)

Dose Range Reduction Interval Total at This Phase
60 mg → 40 mg -5 to -10 mg Every 2 weeks ~4-8 weeks
40 mg → 20 mg -5 mg Every 2 weeks ~8 weeks
20 mg → 10 mg -2.5 mg Every 2-4 weeks ~8-16 weeks
10 mg → 0 mg -1 mg Every 4 weeks ~10 months
Total taper ~12-24 months

Adjust based on symptoms and ESR/CRP. Relapse at any point: return to last effective dose.


CHANGE LOG

v1.2 (January 30, 2026) - Citation verification: removed 8 unverified PubMed links (converted to plain text) - CPT enrichment: added 3 CPT codes (77080, 86160+86162, 82595)

v1.1 (January 30, 2026) - Standardized structured dosing format across all treatment sections (3A, 3B, 3C, 3D) - Fixed prednisone taper phases to use starting dose of each phase in standard_dose field - Added frequency field to all medications (methylprednisolone, prednisone, calcium/vitamin D, tocilizumab, methotrexate, acetaminophen, TMP-SMX)

v1.0 (January 30, 2026) - Initial creation - Section 1: 13 core labs (1A), 9 extended workup (1B), 4 rare/specialized (1C) - Section 2: 5 essential imaging/studies (2A), 5 extended (2B), 3 rare (2C) - Section 3: 4 subsections: - 3A: 3 acute/emergent treatments (IV pulse steroids, aspirin, GI prophylaxis) - 3B: 6 standard glucocorticoid treatments (initial dose through taper + bone protection) - 3C: 4 steroid-sparing therapies (tocilizumab, methotrexate, folic acid, leflunomide) - 3D: 4 symptomatic treatments - Section 4: 9 referrals (4A), 10 patient instructions (4B), 7 lifestyle/prevention recommendations (4C) - Section 5: 13 differential diagnoses - Section 6: 14 monitoring parameters - Section 7: 6 disposition criteria - Section 8: 17 evidence references with PubMed links - Clinical Decision Support Notes: ACR 1990 criteria, clinical presentations, vision loss prevention pathway, steroid taper schedule