Parkinson's Disease - New Diagnosis

VERSION: 1.0 CREATED: January 29, 2026 REVISED: January 29, 2026 STATUS: Approved

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DIAGNOSIS: Parkinson's Disease - New Diagnosis

ICD-10: G20 (Parkinson's disease), G20.A1 (Parkinson's disease without dyskinesia, without motor fluctuations), G20.A2 (Parkinson's disease without dyskinesia, with motor fluctuations), G20.B1 (Parkinson's disease with dyskinesia, without motor fluctuations), G20.B2 (Parkinson's disease with dyskinesia, with motor fluctuations), G20.C (Parkinsonism, unspecified)

CPT CODES: 85025 (CBC), 80053 (CMP), 84443 (TSH), 82607 (Vitamin B12), 86592 (RPR/VDRL), 82390 (Serum ceruloplasmin), 87389 (HIV), 70551 (MRI brain without contrast), 70552 (MRI brain with contrast), 78830 (DaTscan), 78608 (FDG-PET brain), 95810 (Polysomnography)

SYNONYMS: Parkinson disease, PD, idiopathic parkinsonism, paralysis agitans, shaking palsy, primary parkinsonism, Parkinson's, parkinsonism, tremor-dominant PD, PIGD

SCOPE: Initial diagnosis and early management of idiopathic Parkinson's disease in adults. Covers diagnostic workup to exclude secondary causes and atypical parkinsonism, initiation of symptomatic therapy, and patient education. Excludes drug-induced parkinsonism, atypical parkinsonian syndromes (PSP, MSA, CBD, DLB), juvenile/young-onset PD, and advanced PD with motor fluctuations.

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DEFINITIONS: - Parkinsonism: Clinical syndrome of bradykinesia plus rest tremor and/or rigidity - Parkinson's Disease (PD): Neurodegenerative disorder characterized by parkinsonism due to loss of dopaminergic neurons in substantia nigra - Bradykinesia: Slowness of movement with progressive reduction in speed and amplitude with repetitive actions - Rest Tremor: 4-6 Hz tremor present at rest, suppressed with action - Rigidity: Increased resistance to passive movement (cogwheel or lead-pipe)

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DIAGNOSTIC CRITERIA (MDS Clinical Diagnostic Criteria for PD, 2015):

Essential Criteria: - Parkinsonism (bradykinesia + rest tremor OR rigidity)

Supportive Criteria (≥2 for clinically established PD): - Clear beneficial response to dopaminergic therapy - Presence of levodopa-induced dyskinesias - Rest tremor of a limb - Olfactory loss or cardiac sympathetic denervation on MIBG

Absolute Exclusion Criteria: - Cerebellar abnormalities - Downward vertical supranuclear gaze palsy - Diagnosis of probable behavioral variant FTD or primary progressive aphasia - Parkinsonism restricted to lower limbs for >3 years - Treatment with dopamine receptor blocker or dopamine-depleting agent - Absence of response to high-dose levodopa - Unequivocal cortical sensory loss, clear limb ideomotor apraxia, progressive aphasia - Normal functional neuroimaging of presynaptic dopaminergic system

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

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1. LABORATORY WORKUP

1A. Essential/Core Labs

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
CBC (CPT 85025)	-	ROUTINE	ROUTINE	-	General health, rule out anemia	Normal
CMP (CPT 80053)	-	ROUTINE	ROUTINE	-	Hepatic/renal function for medication dosing	Normal
TSH (CPT 84443)	-	ROUTINE	ROUTINE	-	Hypothyroidism can cause slowness/tremor	Normal
Vitamin B12 (CPT 82607)	-	ROUTINE	ROUTINE	-	Deficiency can cause parkinsonism	>400 pg/mL
RPR/VDRL (CPT 86592)	-	ROUTINE	ROUTINE	-	Neurosyphilis in differential	Negative

1B. Extended Workup (Second-line)

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Serum ceruloplasmin (CPT 82390)	-	ROUTINE	ROUTINE	-	Wilson disease if age <50	20-40 mg/dL
24-hour urine copper	-	EXT	EXT	-	Wilson disease if ceruloplasmin low/borderline	<100 mcg/24h
HIV (CPT 87389)	-	ROUTINE	ROUTINE	-	HIV-associated parkinsonism	Negative
Genetic testing (GBA, LRRK2, PRKN)	-	-	EXT	-	Young onset (<50), family history, Ashkenazi Jewish	Informational
Alpha-synuclein seed amplification assay	-	-	EXT	-	Emerging biomarker for synucleinopathy	Pending validation

1C. Rare/Specialized

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Serum/urine heavy metals	-	-	EXT	-	Manganese exposure, other toxins	Negative
Anti-neuronal antibodies	-	-	EXT	-	Autoimmune parkinsonism (rare)	Negative
Skin biopsy for alpha-synuclein	-	-	EXT	-	Emerging biomarker	Research only

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2. DIAGNOSTIC IMAGING & STUDIES

2A. Essential/First-line

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MRI brain without contrast (CPT 70551)	-	ROUTINE	ROUTINE	-	At diagnosis	Rule out structural cause, vascular parkinsonism	Pacemaker, metal
MRI brain with contrast (CPT 70552)	-	ROUTINE	ROUTINE	-	If mass or infection suspected	Rule out structural lesion	Contrast allergy, renal disease

2B. Extended

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
DaTscan (CPT 78830)	-	-	ROUTINE	-	Diagnostic uncertainty (ET vs PD, drug-induced)	Reduced striatal uptake in PD	Pregnancy, iodine allergy
FDG-PET brain (CPT 78608)	-	-	EXT	-	Distinguish atypical parkinsonism	Hypometabolism pattern varies by diagnosis	Per PET
MRI susceptibility-weighted imaging	-	ROUTINE	ROUTINE	-	Wilson disease, iron deposition	Rule out basal ganglia abnormalities	Per MRI
MIBG cardiac scintigraphy	-	-	EXT	-	Distinguish PD from MSA	Reduced uptake in PD	Drugs affecting uptake
Polysomnography (CPT 95810)	-	-	ROUTINE	-	If REM sleep behavior disorder suspected	Confirm RBD	None
Olfactory testing (UPSIT)	-	-	ROUTINE	-	Supportive criterion; impaired in PD	Hyposmia	Nasal obstruction

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3. TREATMENT

3A. Dopaminergic Therapy - Levodopa

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Carbidopa/Levodopa (Sinemet)	PO	-	100 mg :: PO :: TID :: Start 25/100 mg TID with meals; titrate by 25/100 mg q1-2 weeks; usual maintenance 300-800 mg levodopa/day	Narrow-angle glaucoma; caution with MAOIs	Dyskinesia, nausea, orthostatic hypotension	-	ROUTINE	ROUTINE	-
Carbidopa/Levodopa CR	PO	-	200 mg :: PO :: BID :: 25/100 or 50/200 mg BID-TID; ~30% less bioavailable than IR	Same	Same; less predictable absorption	-	ROUTINE	ROUTINE	-
Carbidopa/Levodopa ODT (Parcopa)	-	-	N/A :: - :: per protocol :: Same dosing as IR; dissolves on tongue	Same	Same; useful for dysphagia	-	ROUTINE	ROUTINE	-
Carbidopa/Levodopa ER (Rytary)	PO	-	95 mg :: PO :: TID :: Start 23.75/95 mg TID; titrate per response	Same	Same; more sustained release	-	-	ROUTINE	-
Carbidopa/Levodopa intestinal gel (Duopa)	IV	-	N/A :: IV :: continuous :: Continuous infusion via PEG-J; specialist prescribing	Advanced PD; requires surgical placement	Device complications	-	-	EXT	-

3B. Dopamine Agonists

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Pramipexole (Mirapex)	PO	-	0.125 mg :: PO :: TID :: Start 0.125 mg TID; titrate weekly to 0.5-1.5 mg TID; max 4.5 mg/day	Impulse control disorders (relative); renal impairment (reduce dose)	ICDs (gambling, hypersexuality, shopping), sleepiness, hallucinations	-	ROUTINE	ROUTINE	-
Pramipexole ER	PO	-	0.375 mg :: PO :: daily :: Start 0.375 mg daily; titrate weekly; max 4.5 mg/day	Same	Same	-	ROUTINE	ROUTINE	-
Ropinirole (Requip)	PO	-	0.25 mg :: PO :: TID :: Start 0.25 mg TID; titrate weekly to 3-8 mg TID; max 24 mg/day	ICDs, hepatic impairment	Same as pramipexole	-	ROUTINE	ROUTINE	-
Ropinirole XL	PO	-	2 mg :: PO :: daily :: Start 2 mg daily; titrate weekly; max 24 mg/day	Same	Same	-	ROUTINE	ROUTINE	-
Rotigotine patch (Neupro)	Transdermal	-	2 mg :: PO :: - :: Start 2 mg/24h; increase by 2 mg/week; max 8 mg/24h (early PD)	Sulfite allergy, application site reactions	ICDs, skin reactions	-	ROUTINE	ROUTINE	-
Apomorphine SC (Apokyn)	SC	-	0.2 mL :: PO :: - :: Rescue for off episodes; start 0.2 mL (2 mg) test dose; max 0.6 mL (6 mg)	Severe hypotension, 5-HT3 antagonist use	BP, nausea (pretreat with trimethobenzamide)	-	-	EXT	-

3C. MAO-B Inhibitors

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Rasagiline (Azilect)	-	-	0.5-1 mg :: - :: daily :: 0.5-1 mg daily; may use as monotherapy early PD or adjunct	MAOIs, meperidine, tramadol, methadone, cyclobenzaprine	Serotonin syndrome; insomnia if taken late	-	ROUTINE	ROUTINE	-
Selegiline (Eldepryl)	PO	-	5 mg :: PO :: BID :: 5 mg BID (breakfast and lunch); avoid evening dosing	Same as rasagiline	Insomnia, orthostatic hypotension	-	ROUTINE	ROUTINE	-
Selegiline ODT (Zelapar)	-	-	1.25-2.5 mg :: - :: daily :: 1.25-2.5 mg daily (buccal absorption)	Same	Same	-	ROUTINE	ROUTINE	-
Safinamide (Xadago)	PO	-	50-100 mg :: PO :: daily :: 50-100 mg daily; adjunct to levodopa	Same; severe hepatic impairment, retinal disease	Dyskinesia, falls	-	-	ROUTINE	-

3D. COMT Inhibitors (Adjunct to Levodopa)

Treatment	Route	Indication	Dosing	Pre-Treatment Requirements	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Entacapone (Comtan)	PO	-	200 mg :: PO :: - :: 200 mg with each levodopa dose; max 8 doses/day	-	None absolute	Orange urine, diarrhea, dyskinesia	-	ROUTINE	ROUTINE	-
Carbidopa/Levodopa/Entacapone (Stalevo)	-	-	N/A :: - :: per protocol :: Various strengths; replace existing C/L with equivalent	-	Same	Same	-	ROUTINE	ROUTINE	-
Opicapone (Ongentys)	PO	-	50 mg :: PO :: daily :: 50 mg daily at bedtime; separate from levodopa by 1 hour	-	None absolute	Dyskinesia, constipation	-	-	ROUTINE	-
Tolcapone (Tasmar)	-	-	100-200 mg :: - :: TID :: 100-200 mg TID; rarely used due to hepatotoxicity	-	Hepatic disease	LFTs q2-4 weeks x6mo, then periodically	-	-	EXT	-

3E. Anticholinergics (Tremor-predominant, Younger Patients)

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Trihexyphenidyl (Artane)	PO	-	1 mg :: PO :: daily :: Start 1 mg daily; titrate to 2 mg TID; max 15 mg/day	Glaucoma, urinary retention, cognitive impairment, age >65	Confusion, urinary retention, dry mouth	-	ROUTINE	ROUTINE	-
Benztropine (Cogentin)	PO	-	0.5 mg :: PO :: daily :: Start 0.5 mg daily; titrate to 1-2 mg BID; max 6 mg/day	Same	Same	-	ROUTINE	ROUTINE	-

3F. Amantadine

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Amantadine IR	PO	-	100 mg :: PO :: BID :: 100 mg BID-TID; avoid evening dosing	Renal impairment (reduce dose), seizures	Livedo reticularis, edema, hallucinations, insomnia	-	ROUTINE	ROUTINE	-
Amantadine ER (Gocovri)	PO	-	137-274 mg :: PO :: - :: 137-274 mg at bedtime; for dyskinesia	Same	Same	-	-	ROUTINE	-

3G. Non-Motor Symptom Treatment

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Rivastigmine (cognitive)	PO	-	4.6-13.3 mg :: PO :: - :: Patch 4.6-13.3 mg/24h; for PD dementia	GI bleeding, bradycardia	Nausea, bradycardia	-	-	ROUTINE	-
Quetiapine (psychosis)	-	-	12.5-100 mg :: - :: QHS :: 12.5-100 mg QHS; does not worsen parkinsonism	Metabolic syndrome	Sedation, glucose, QTc	-	ROUTINE	ROUTINE	-
Pimavanserin (Nuplazid)	PO	-	34 mg :: PO :: daily :: 34 mg daily; for PD psychosis	QTc prolongation	QTc monitoring	-	-	ROUTINE	-
Droxidopa (orthostatic hypotension)	-	-	100 mg :: PO :: TID :: Start 100 mg TID; max 600 mg TID	Supine HTN	BP supine and standing	-	ROUTINE	ROUTINE	-
Fludrocortisone (orthostatic hypotension)	-	-	0.1-0.2 mg :: PO :: daily :: 0.1-0.2 mg daily	Heart failure, HTN	K+, edema, supine BP	-	ROUTINE	ROUTINE	-
Polyethylene glycol (constipation)	PO	-	17 g :: PO :: daily :: 17 g daily in water	Bowel obstruction	Bowel movements	-	ROUTINE	ROUTINE	-

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4. OTHER RECOMMENDATIONS

4A. Referrals & Consults

Recommendation	ED	HOSP	OPD	ICU	Indication
Movement disorder specialist	-	ROUTINE	ROUTINE	-	All new PD diagnoses for confirmation and management
Physical therapy	-	ROUTINE	ROUTINE	-	Gait training, balance, LSVT-BIG program
Occupational therapy	-	ROUTINE	ROUTINE	-	ADL assistance, home safety evaluation
Speech therapy (LSVT-LOUD)	-	ROUTINE	ROUTINE	-	Hypophonia, dysarthria, dysphagia assessment
Neuropsychology	-	-	ROUTINE	-	Cognitive concerns, baseline assessment
Psychiatry	-	ROUTINE	ROUTINE	-	Depression, anxiety, impulse control disorders
Social work	-	ROUTINE	ROUTINE	-	Resources, support groups, caregiver support
Nutrition/Dietitian	-	ROUTINE	ROUTINE	-	Weight management, protein timing with levodopa
Sleep medicine	-	-	ROUTINE	-	REM sleep behavior disorder, excessive daytime sleepiness
Urology	-	-	ROUTINE	-	Urinary symptoms, erectile dysfunction

4B. Patient/Family Instructions

Recommendation	ED	HOSP	OPD
PD is a chronic condition managed with medications; not curable but treatable	-	ROUTINE	ROUTINE
Take levodopa 30-60 minutes before meals for best absorption; protein can reduce effect	-	ROUTINE	ROUTINE
Report impulse control changes (gambling, shopping, hypersexuality) immediately	-	ROUTINE	ROUTINE
Do NOT stop PD medications abruptly - risk of severe withdrawal/NMS	-	ROUTINE	ROUTINE
Fall prevention: remove rugs, improve lighting, use assistive devices as needed	-	ROUTINE	ROUTINE
Exercise is essential: walking, tai chi, boxing, cycling all beneficial	-	ROUTINE	ROUTINE
Join support group (Parkinson's Foundation, Michael J. Fox Foundation)	-	-	ROUTINE
Advance directives discussion early in disease course	-	-	ROUTINE

4C. Lifestyle & Prevention

Recommendation	ED	HOSP	OPD
Regular aerobic exercise (30+ min, 5 days/week) - may slow progression	-	ROUTINE	ROUTINE
Maintain social activities and cognitive engagement	-	ROUTINE	ROUTINE
Fall prevention strategies	-	ROUTINE	ROUTINE
Avoid medications that worsen parkinsonism (metoclopramide, typical antipsychotics, prochlorperazine)	-	ROUTINE	ROUTINE
Mediterranean diet associated with better outcomes	-	-	ROUTINE
Optimize sleep hygiene	-	ROUTINE	ROUTINE
Caffeine may have protective effect (moderate consumption)	-	-	ROUTINE

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5. DIFFERENTIAL DIAGNOSIS

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Essential tremor	Action/postural tremor (not rest), bilateral, head tremor, family history, alcohol-responsive	Clinical; DaTscan normal in ET
Drug-induced parkinsonism	Medication history (antipsychotics, metoclopramide), symmetric, may resolve with drug withdrawal	Medication review; DaTscan often normal
Vascular parkinsonism	Lower-body predominant, gait disorder, stepwise progression, vascular risk factors, MRI white matter changes	MRI brain; poor levodopa response
Progressive supranuclear palsy (PSP)	Early falls (backward), vertical gaze palsy, axial rigidity > limb, poor levodopa response	MRI (hummingbird sign), clinical
Multiple system atrophy (MSA)	Early autonomic failure, cerebellar signs (MSA-C), poor levodopa response	MRI (hot cross bun sign), MIBG preserved in MSA
Corticobasal degeneration (CBD)	Asymmetric apraxia, alien limb, cortical sensory loss, dystonia	MRI (asymmetric cortical atrophy), clinical
Dementia with Lewy bodies (DLB)	Dementia before or within 1 year of parkinsonism, visual hallucinations, fluctuations	Clinical criteria; DaTscan abnormal
Normal pressure hydrocephalus (NPH)	Gait apraxia (magnetic gait), urinary incontinence, dementia; triad	MRI (ventriculomegaly), LP with large volume tap
Wilson disease	Age <50, KF rings, hepatic/psychiatric symptoms, tremor may be wing-beating	Ceruloplasmin, 24h urine copper, slit lamp exam

6. MONITORING PARAMETERS

Parameter	ED	HOSP	OPD	ICU	Frequency	Target/Threshold	Action if Abnormal
UPDRS/MDS-UPDRS	-	ROUTINE	ROUTINE	-	Each visit	Stable or improved scores	Adjust medications
Orthostatic vitals	-	ROUTINE	ROUTINE	-	Each visit	<20 mmHg SBP drop	Midodrine, droxidopa, compression stockings
Impulse control screening	-	ROUTINE	ROUTINE	-	Each visit	Negative	Reduce/discontinue dopamine agonist
Cognitive screening (MoCA)	-	-	ROUTINE	-	Annually or if concerns	≥26	Rivastigmine if dementia
Depression screening (BDI, PHQ-9)	-	ROUTINE	ROUTINE	-	q6 months	Negative	Treat depression
Falls assessment	-	ROUTINE	ROUTINE	-	Each visit	None or decreasing	PT, home safety, assistive devices
Dysphagia screening	-	ROUTINE	ROUTINE	-	Annually or if concerns	Safe swallow	Speech therapy, modified diet
Weight	-	ROUTINE	ROUTINE	-	Each visit	Stable	Nutrition consult
Blood pressure (supine and standing)	-	ROUTINE	ROUTINE	-	Each visit	No symptomatic orthostasis	Address as above

7. DISPOSITION CRITERIA

Disposition	Criteria
Outpatient management	Most new PD diagnoses; able to perform ADLs, stable home environment
Admit to hospital	Acute deterioration (infection causing worsening), severe "off" episodes, inability to take PO medications, falls with injury, psychosis
Discharge from hospital	Medications optimized, safe swallow, ambulatory (with assistance if needed), caregiver support
Movement disorder specialist referral	All new diagnoses (confirmation), young onset, atypical features, diagnostic uncertainty, motor fluctuations, dyskinesia, DBS candidacy

8. EVIDENCE & REFERENCES

Recommendation	Evidence Level	Source
MDS Clinical Diagnostic Criteria for PD	Class I	Postuma et al., Mov Disord 2015
Levodopa most effective symptomatic therapy	Class I, Level A	Cochrane Reviews
Dopamine agonists monotherapy early PD	Class I, Level A	Multiple RCTs
MAO-B inhibitors mild symptomatic benefit	Class I, Level A	ADAGIO, TEMPO trials
DaTscan useful for uncertain parkinsonism	Class II, Level B	FDA approved 2011
Exercise may slow disease progression	Class II, Level B	Observational data, RCTs ongoing
LSVT-LOUD effective for speech	Class I, Level A	Multiple RCTs
LSVT-BIG effective for movement	Class I, Level A	Multiple RCTs
Pimavanserin for PD psychosis	Class I, Level A	FDA approved 2016
Rivastigmine for PD dementia	Class I, Level A	EXPRESS study
Avoid anticholinergics in elderly	Class II, Level B	Cognitive impairment risk

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NOTES

• PD is a clinical diagnosis; DaTscan supports but does not confirm diagnosis
• Start treatment when symptoms interfere with function or quality of life; no need to wait
• Levodopa is most effective but traditionally delayed due to dyskinesia concerns; recent evidence suggests early levodopa is safe
• Dopamine agonists preferred in younger patients (<65) due to lower dyskinesia risk, but watch for impulse control disorders
• MAO-B inhibitors may have disease-modifying potential (unproven) and are good early monotherapy option
• "Drug holiday" is dangerous - never abruptly stop PD medications (risk of neuroleptic malignant-like syndrome)
• Medications that worsen PD: metoclopramide, prochlorperazine, typical antipsychotics, reserpine, tetrabenazine
• Exercise and physical therapy are as important as medications

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CHANGE LOG

v1.0 (January 29, 2026) - Initial template creation - Complete medication classes with dosing - MDS diagnostic criteria included - Non-motor symptom treatments - Comprehensive differential diagnosis