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Diagnosis guide for clinicians

Myasthenia gravis: when to suspect it and what to test

Not a doctor or health care professional? This page is for clinicians.Go to the patient version

Myasthenia gravis is an autoimmune disease of the neuromuscular junction, most often caused by antibodies to the acetylcholine receptor (AChR) and less often to MuSK or LRP4.Source Israel national guideline

It often begins with a drooping eyelid, double vision or both, and weakness worsens with repeated muscle use and improves with rest.

Source NORD

In a UCB-funded Copenhagen cohort of 315 patients, time to diagnosis averaged 331 days and ranged from 5 to 4492 days.

Source Marlet 2024 Copenhagen cohort
331 daysMean time to diagnosis in a UCB-funded Copenhagen cohort of 315 patients; the median was 141 daysMarlet 2024 Copenhagen cohort
About 50%Share of ocular myasthenia with AChR binding antibodies on radioimmunoassay, against up to 85% of generalized diseaseRousseff 2021 diagnostic review
15% to 20%People with myasthenia gravis who have at least 1 myasthenic crisis, according to NINDSNINDS
G70.00, G70.01ICD-10-CM codes, myasthenia gravis without or with (acute) exacerbationNLM ICD-10-CM lookup
Orphanet recordORPHA:589 ↗
Inheritance
Multigenic/multifactorial, Not applicable
Age of onset
All ages
Prevalence
  • 1 to 9 per 100,000 point prevalence, Worldwide
  • 1 to 9 per 1,000,000 annual incidence, Worldwide
  • 1 to 9 per 1,000,000 annual incidence, United States
Also called
Acquired myasthenia, Autoimmune myasthenia gravis

Live from Orphanet (INSERM) via Orphadata, licensed CC BY 4.0, data version 2026-06-23.

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Patterns to testRed flagsOften mistaken forWhat to testFamily screeningICD-10 codesOnce confirmedFor the patient

Patterns that should prompt a test for Myasthenia gravis

Each sign below is common on its own, which is why Myasthenia gravis is missed. Published studies describe these combinations as the picture to act on. Rows are ordered from the highest published figure to the lowest, within each kind of measure.

Where testing finds it

Share of each screened or biopsied group found to have Myasthenia gravis, from the cited studies. A bar spans the lowest to the highest published figure.

  1. 1

    Ptosis+Referral for suspected ocular myasthenia

    155 consecutive patients referred with ptosis and suspected ocular myasthenia

    Ocular myasthenia was the final diagnosis in 102 of 155 (65.8%) of everyone referred, whatever the test results; the ice pack test had 86% sensitivity and 79% specificity (Giannoccaro 2020).Giannoccaro 2020 ice pack study

    65.8%
  2. 2

    Clinical suspicion of myasthenia gravis+AChR or MuSK antibody testing by fixed cell-based assay

    770 patients tested at a Canadian center that used fixed cell-based assays as first-line testing from 2021 to 2024

    Antibodies were found in 109 of 770 (14%), and 108 of the 109 were judged true positives, a positive predictive value of 99% (Li 2025).Li 2025 fixed cell-based assay study

    14%
  3. 3

    Clinical myasthenia gravis+Negative AChR and MuSK antibodies on conventional assays+Retesting by live cell-based assay

    82 radioimmunoassay-negative patients in an Italian and UK study, and 67 conventionally tested seronegative patients in a German study

    Clustered AChR antibodies were found in 19.5% of 82 patients (Damato 2022) but only 4.5% of 67 (Hoffmann 2023); these are antibody yields, not diagnoses.Damato 2022 cell-based assay study

    4.5% to 19.5%
  4. 4

    Age 75 or older+A stroke or transient ischemic attack label

    Sera from a sample of 2000 people aged 60 or older in the UK, tested for AChR antibodies

    AChR antibodies were found in 8 people aged 75 or older (0.7% of that age group, with or without a stroke history); 1 had known myasthenia gravis and 4 others had stroke or TIA histories (Vincent 2003).Vincent 2003 UK survey

    0.7%

How often diagnosed patients show it

Share of patients already diagnosed who had the finding, in the group named on each row. Groups differ by age and type, so read each row with its group.

  1. 1

    Onset at age 65 or older+Ptosis as the first symptom+Swallowing difficulty

    240 patients with onset at age 65 or older treated at PLA General Hospital from 2003 to 2023

    The first symptom was ptosis in 78.8% and diplopia in 18.8%; swallowing dysfunction occurred in 41.7% and thymoma in 14.2% (Sun 2024).Sun 2024 late-onset cohort

    78.8%
  2. 2

    Fluctuating ptosis or diplopia+No limb, bulbar or breathing weakness

    65 adults diagnosed with myasthenia gravis in Olmsted County, Minnesota, from 1990 to 2017

    Isolated ocular disease was the presentation in 33 of 65 (51%), and 18 of the 33 (55%) later generalized at a median of 13 months (Hendricks 2019).Hendricks 2019 Olmsted County study

    51%
  3. 3

    Cancer immunotherapy with a checkpoint inhibitor started in recent weeks+New ocular, bulbar or respiratory weakness+Concurrent myositis or myocarditis

    63 patients with checkpoint inhibitor-related myasthenia gravis in a review cited by the 2020 international consensus guidance

    Onset was a median of 4 weeks after starting treatment; 37% had myositis, 8% myocarditis and 45% respiratory failure needing ventilation.2020 international consensus update

    37%
  4. 4

    Known or suspected myasthenia gravis+Worsening swallowing or breathing during a respiratory infection+Prior crisis, MuSK antibodies or thymoma

    People with myasthenia gravis, as summarized in a 2023 Muscle and Nerve review

    Crisis occurs in about 15% to 20% of patients, usually in the first 2 to 3 years; 30% to 40% have no identified trigger (Claytor 2023).Claytor 2023 crisis review

    15% to 20%
  5. 5

    Isolated dropped head or bilateral facial weakness+Hand or foot drop+MuSK antibodies

    290 patients with myasthenia gravis at Bursa Uludag University, Turkey

    Unusual presentations were found in 20 of 290 (6.9%), with MuSK antibodies more common in that group (Oguz-Akarsu 2025).Oguz-Akarsu 2025 Turkish series

    6.9%

Also described, without a comparable figure

  • Sudden isolated dysarthria + Older age with a first diagnosis of stroke: Described in case series; the authors note that lacunar stroke with only dysarthria is also unusual (Tremolizzo 2015).Tremolizzo 2015 case series

These figures describe published study groups. They are not the chance that any one patient has Myasthenia gravis, and bars whose ranges overlap are not in a settled order.

Red flags for Myasthenia gravis

What the cited sources describe, grouped by life stage and organ. Each line links to its source.

Eyes: what ophthalmology and primary care see first

  • Ptosis, diplopia or both that vary from hour to hour or day to day, worse with repeated muscle use and better after rest.NORD
  • In a Minnesota population study, 33 of 65 adults with myasthenia gravis (51%) presented with isolated ocular disease.Hendricks 2019 Olmsted County study
  • Of those 33 patients, 18 (55%) later developed generalized disease, at a median of 13 months.Hendricks 2019 Olmsted County study
  • Among 240 patients with onset at age 65 or older, the first symptom was ptosis in 78.8% and diplopia in 18.8%.Sun 2024 late-onset cohort
  • A Turkish series of 290 patients included eye movement findings without ptosis, such as a pseudo sixth nerve palsy.Oguz-Akarsu 2025 Turkish series

Speech, swallowing and voice: what ENT and emergency physicians see

  • A voice that sounds weak, hoarse or nasal, with trouble chewing and swallowing that can lead to choking, coughing or aspiration.NORD
  • A laryngology series describes 5 patients whose primary complaint was dysphagia, with residue or pharyngeal weakness on swallow evaluation, before myasthenia gravis was diagnosed.Moffatt 2024 laryngology series
  • Its authors call myasthenia gravis an important differential diagnosis in unexplained pharyngeal dysphagia.Moffatt 2024 laryngology series
  • Sudden isolated dysarthria in an older adult; an Italian case series notes that lacunar stroke with only this presentation is also unusual.Tremolizzo 2015 case series
  • Swallowing dysfunction was recorded in 41.7% of 240 patients with onset at age 65 or older, and thymoma in 14.2%.Sun 2024 late-onset cohort
  • NORD notes that some people with MuSK antibodies develop muscle atrophy, especially of the face and tongue.NORD

Limbs, neck and breathing

  • Weakness of the upper arms and legs with easy fatigue, alongside facial weakness.NORD
  • NINDS lists shortness of breath and weakness in the arms, hands, fingers, legs and neck among common symptoms.NINDS
  • In a Turkish series, 20 of 290 patients (6.9%) had unusual onsets such as isolated dropped head, bilateral facial weakness or hand or foot drop.Oguz-Akarsu 2025 Turkish series
  • MuSK antibodies were more common in the unusual-onset group of that series than in the rest.Oguz-Akarsu 2025 Turkish series
  • An emergency medicine review lists normal reflexes, normal sensation, no autonomic symptoms, no fasciculations and weakness that worsens with repetitive motion.Roper 2017 emergency medicine review

Older adults

  • NINDS says the disease most commonly affects women under 40 and men over 60, but can occur at any age.NINDS
  • A UK study of sera from 2000 people aged 60 or older found AChR antibodies in 8 of those aged 75 or older (0.7%); only 1 had a known diagnosis.Vincent 2003 UK survey
  • Four of the other 7 had histories of stroke or transient ischemic attack, and the authors concluded the disease may be substantially underdiagnosed in older people.Vincent 2003 UK survey
  • A Mayo Clinic Proceedings report states that 13% to 20% of all patients are in the seventh decade of life or beyond.Kleiner-Fisman 1998 case report
  • An AstraZeneca-supported Gulf consensus notes that ptosis, diplopia and facial muscle problems may be harder to detect in the elderly.Gulf consensus

New weakness after a new drug or cancer immunotherapy

  • The 2020 international consensus guidance reports new myasthenia gravis with immune checkpoint inhibitors, at an estimated 0.12% to 0.2% with PD-1 inhibitors.2020 international consensus update
  • In a review of 63 such patients it cites, onset was a median of 4 weeks after starting treatment. Myositis was also present in 37%, myocarditis in 8%, and respiratory failure needing mechanical ventilation in 45%.2020 international consensus update
  • The Keytruda label lists myasthenic syndrome or myasthenia gravis, including exacerbation, among immune-mediated adverse reactions.Keytruda label
  • The Zithromax label reports exacerbations of myasthenia gravis and new onset of myasthenic syndrome in patients receiving azithromycin.Zithromax label
  • According to the MGFA, D-penicillamine is strongly associated with causing myasthenia gravis, and statins may worsen or precipitate it.MGFA cautionary drugs list

Signs of impending crisis

  • The 2016 international consensus guidance defines impending crisis as rapid clinical worsening that could lead to crisis within days to weeks.2016 international consensus guidance
  • It defines manifest crisis as worsening weakness requiring intubation or noninvasive ventilation, with possible airway compromise from ventilatory or bulbar dysfunction.2016 international consensus guidance
  • NORD describes crisis as sudden, severe weakness of the jaw, throat or respiratory muscles that can require respiratory support.NORD
  • A Muscle and Nerve review puts crisis at about 15% to 20% of patients, usually within the first 2 to 3 years of disease, and says most episodes do not occur suddenly.Claytor 2023 crisis review
  • The same review lists prior crisis, severe disease, oropharyngeal weakness, MuSK antibodies and thymoma as higher risk, with respiratory infection the most common trigger and no trigger found in 30% to 40%.Claytor 2023 crisis review
  • The 2016 guidance says impending crisis requires hospital admission and close observation of respiratory and bulbar function.2016 international consensus guidance

Myasthenia gravis is often mistaken for

Diagnoses patients commonly carry first, and why the sources say they are confused.

First diagnosisWhy it is confused
Stroke or transient ischemic attackTwo elderly women were first diagnosed with ischemic stroke by neurologists; incidental neuroimaging findings were taken as confirmation.Kleiner-Fisman 1998 case report
Lacunar strokeAn Italian case series describes myasthenia gravis starting with sudden dysarthria, and calls the disease under-recognized in the elderly.Tremolizzo 2015 case series
Brainstem stroke or cranial nerve palsyNORD says ocular myasthenia may be confused with a stroke in the brainstem or in the nerves that control eye movements.NORD
Thyroid eye diseaseA Muscle and Nerve review says the 2 conditions share clinical features and sometimes coexist, which makes ocular myasthenia hard to confirm.Claytor 2021 thyroid eye disease review
Anxiety disorderA 54-year-old woman with bulbar onset and no daily fluctuation was first treated for anxiety, and the psychiatric drugs eventually worsened her condition.Gasparini 2025 case report
Psychosomatic illnessCharité authors, in a study partly funded by argenx, write that symptoms of antibody-negative patients are sometimes misinterpreted as psychosomatic, which delays diagnosis.Lehnerer 2025 seronegative burden study
Women's health complaintsIn an Alexion-funded US survey, patients named clinicians mistaking symptoms for female health issues as a source of delay.Jiang 2025 US patient journey survey
Changes put down to ageAn AstraZeneca-supported Gulf consensus notes that ptosis, diplopia and facial weakness may be harder to detect in the elderly.Gulf consensus
Bell's palsy, diabetic cranial nerve palsy or radiculopathyThese were first diagnoses in a Turkish series of unusual onsets, made mostly in primary and secondary care hospitals or by non-neurology specialists.Oguz-Akarsu 2025 Turkish series
Fibromyalgia, rheumatic disease, myopathy or depressive disorderThe same series lists these among first diagnoses given to patients with limb or neck onset.Oguz-Akarsu 2025 Turkish series
Amyotrophic lateral sclerosisTwo patients in the Turkish series, with hand drop or breathing difficulty at onset, first carried this diagnosis.Oguz-Akarsu 2025 Turkish series

Codes patients often carry before this diagnosis

For spotting the pattern in a problem list or registry. Descriptions are checked daily against NLM's ICD-10-CM service; this is not coding advice.

Unspecified ptosis of the right, left, bilateral or unspecified eyelids H02.401, H02.402, H02.403, H02.409

The disorder often begins with drooping of the upper eyelids, according to NORD.NORD

Diplopia H53.2

Double vision from eye muscle weakness is a common first symptom, alone or with ptosis.NORD

Sixth [abducent] nerve palsy H49.20, H49.21, H49.22

A Turkish series describes myasthenia gravis presenting as a pseudo sixth nerve palsy without ptosis.Oguz-Akarsu 2025 Turkish series

Dysphagia, unspecified, oropharyngeal phase or pharyngeal phase R13.10, R13.12, R13.13

A laryngology series describes dysphagia as the primary complaint before diagnosis.Moffatt 2024 laryngology series

Dysarthria and anarthria R47.1

Sudden isolated dysarthria was the onset in an Italian case series of patients first thought to have stroke.Tremolizzo 2015 case series

Cerebral infarction, unspecified, or transient cerebral ischemic attack, unspecified I63.9, G45.9

Four of 7 previously undiagnosed antibody-positive people aged 75 or older in a UK study had stroke or TIA histories.Vincent 2003 UK survey

Anxiety disorder, unspecified F41.9

A case report describes bulbar-onset disease first diagnosed and treated as an anxiety disorder.Gasparini 2025 case report

Other fatigue R53.83

Excessive muscle fatigue after activity is a core feature in NORD's description.NORD

Testing for Myasthenia gravis, step by step

The testing order the cited guidance describes, by who it applies to. It summarizes published guidance and is not a plan for any one patient.

Anyone with fluctuating ptosis, diplopia, bulbar or proximal weakness

  1. History and examination for fatigable weakness

    The German guideline bases the diagnosis on fatigable, fluctuating weakness, confirmed by antibody testing, electrophysiology or pharmacological testing.German guideline

People with ptosis

  1. Ice pack test at the bedside

    In 155 consecutive patients with suspected ocular myasthenia, 102 of whom had it, the test had 86% sensitivity and 79% specificity. When ice pack and single-fiber EMG were both negative, the negative predictive value was 94%.Giannoccaro 2020 ice pack study

Everyone with suspected myasthenia gravis

  1. Order of antibody tests

    Israel's national guideline tests anti-AChR antibodies first, anti-MuSK antibodies if that is negative, and anti-LRP4 antibodies in selected double seronegative cases.Israel national guideline

  2. AChR binding antibody

    A 2021 review reports the radioimmunoassay is abnormal in up to 85% of generalized and about 50% of ocular disease. It describes the test as highly specific in the right clinical setting.Rousseff 2021 diagnostic review

People who test negative for AChR antibodies

  1. MuSK antibody

    The same review puts MuSK antibodies in about 6% to 8% of all cases and calls the radioimmunoassay nearly 100% specific.Rousseff 2021 diagnostic review

Selected people negative for both AChR and MuSK antibodies

  1. LRP4 antibody

    Israel's guideline reserves LRP4 testing for selected double seronegative cases, particularly when the diagnosis remains unclear.Israel national guideline

People with clinical myasthenia gravis who are negative on radioimmunoassay

  1. Cell-based assays

    Live cell-based assays found clustered AChR antibodies in 16 of 82 radioimmunoassay-negative patients (19.5%) and MuSK antibodies in 7 (8.5%).Damato 2022 cell-based assay study

Seronegative people with continuing suspicion

  1. Repeat antibody testing

    A 2021 review says testing may be repeated within 6 to 12 months in selected cases, because delayed seroconversion is well described although rare.Rousseff 2021 diagnostic review

Seronegative or uncertain cases

  1. Repetitive nerve stimulation

    A decrement above 10% is abnormal. A 2021 review reports abnormal proximal muscle studies in 60% to 70% of generalized disease and specificity of about 97%.Rousseff 2021 diagnostic review

Seronegative or ocular cases with normal repetitive stimulation

  1. Single-fiber EMG (jitter)

    The review reports abnormal jitter in 98% to 100% of generalized and above 90% of ocular disease. Jitter is not specific and is also abnormal in neuropathies, some myopathies and motor neuron disease.Rousseff 2021 diagnostic review

Everyone with confirmed myasthenia gravis

  1. Chest CT or MRI for thymoma

    The German guideline says every patient should be evaluated for thymoma with thoracic CT or MRI.German guideline

  2. Why the thymus is imaged

    A 2021 review reports thymoma in up to 15% of patients, mostly those with AChR antibodies, and says CT seems preferred for screening.Rousseff 2021 diagnostic review

Definite or probable myasthenia gravis

  1. Thyroid function tests

    A 2021 review calls thyroid function tests appropriate in all definite or probable cases, to exclude comorbid thyroid disease.Rousseff 2021 diagnostic review

Rarely used

  1. Edrophonium test

    A 2021 review notes edrophonium has been discontinued in the US since 2018 and may worsen weakness in MuSK disease.Rousseff 2021 diagnostic review

Antibody-negative people, depending on the response to immunotherapy

  1. Gene testing for congenital myasthenic syndromes, a separate inherited condition

    The German guideline says congenital myasthenic syndromes should be considered in antibody-negative myasthenia, with molecular genetic testing when suspected. A gene test does not diagnose autoimmune myasthenia gravis.German guideline

Everyone with a confirmed diagnosis

  1. Antibody type and clinical phenotype

    Israel's guideline classifies patients by antibody status and clinical phenotype, and ties treatment choices to both.Israel national guideline

Adults with generalized myasthenia gravis

  1. Antibody status on the Vyvgart label

    The Vyvgart label covers adults with generalized myasthenia gravis and does not name an antibody type.Vyvgart label

  2. Antibody status on the Rystiggo label

    The Rystiggo label covers adults who are anti-AChR or anti-MuSK antibody positive.Rystiggo label

  3. Antibody status on the Zilbrysq label

    The Zilbrysq label covers adults who are anti-AChR antibody positive, and it carries a boxed warning for serious meningococcal infections.Zilbrysq label

People 12 and older with generalized myasthenia gravis

  1. Antibody status on the Imaavy label

    The Imaavy label covers adults and children 12 and older who are anti-AChR or anti-MuSK antibody positive.Imaavy label

Where testing goes wrong

  • A negative antibody test does not exclude the disease; NINDS notes that some people have neither AChR nor MuSK antibodies.NINDS
  • Israel's guideline says ice pack and edrophonium testing should not be the primary diagnostic approach.Israel national guideline
  • A retrospective cohort study put ice test sensitivity at 0.92 and specificity at 0.79, and argued that earlier case-control studies overestimated its value.Fakiri 2013 ice test cohort
  • Yield of cell-based assays varies; a German study found clustered AChR antibodies in only 3 of 67 seronegative patients (4.5%).Hoffmann 2023 German assay study
  • In a Milan cohort of 124 radioimmunoassay-negative patients, fixed cell-based assays found antibodies in 2.4%, against about 20% for live assays.Rinaldi 2026 Milan assay study
  • At a Canadian center using fixed cell-based assays first, 109 of 770 patients tested (14%) were positive for AChR or MuSK antibodies, and 108 of the 109 were true positives.Li 2025 fixed cell-based assay study
  • A 2021 review says LRP4 antibodies are also found in up to 23% of ALS patients and must be read strictly in clinical context.Rousseff 2021 diagnostic review
  • Overdiagnosis also occurs; at a Rome referral clinic, the diagnosis was not confirmed in 26 of 129 patients (20.2%) sent for a second opinion.Falso 2026 Rome misdiagnosis study
  • Predictors of misdiagnosis in that study included absent typical features, no response to pyridostigmine and antibody testing by ELISA.Falso 2026 Rome misdiagnosis study
  • A case series found 8 mimics among 61 patients evaluated, all treated as refractory myasthenia gravis and misdiagnosed for an average of 9 years.Harrison 2023 mimics series
  • A European workshop names myopathies, congenital myasthenic syndromes and functional disorders as the commonest misdiagnoses in seronegative cases.ENMC 2024 seronegative workshop
  • An AstraZeneca-supported Gulf consensus warns against diagnosing on a positive serological test alone when the presentation is atypical.Gulf consensus
  • In people with thyroid eye disease, a single positive test may not secure a diagnosis of ocular myasthenia.Claytor 2021 thyroid eye disease review
  • The Cipro label carries a boxed warning that fluoroquinolones may exacerbate muscle weakness in myasthenia gravis, and says to avoid Cipro in patients with a known history of the disease.Cipro label
  • The magnesium sulfate injection label lists myasthenia gravis as a contraindication, because it can precipitate a myasthenic crisis.Magnesium sulfate injection label
  • The Botox label warns that people with known or unrecognized neuromuscular junction disorders may be at increased risk of severe dysphagia and respiratory compromise from therapeutic doses.Botox label
  • The Timoptic label, for timolol eye drops, says timolol has been reported rarely to increase muscle weakness in some patients with myasthenia gravis or myasthenic symptoms.Timoptic in Ocudose label
  • The MGFA list, drawn from the 2016 consensus guidance, also names telithromycin, macrolides, aminoglycosides, quinine, procainamide, beta blockers and statins.MGFA cautionary drugs list
  • The MGFA adds that corticosteroids, a standard treatment, may cause transient worsening within the first 2 weeks.MGFA cautionary drugs list
  • The MGFA also cautions that many of these reports are rare, and a listed drug is not automatically off limits.MGFA cautionary drugs list
  • The 2016 guidance says many patients with MuSK antibodies respond poorly to cholinesterase inhibitors, and usual pyridostigmine doses often cause side effects.2016 international consensus guidance

Where to test

  • AChR, MuSK and LRP4 antibody assays: Myasthenia gravis is autoimmune and has no diagnostic gene test. A 2021 review notes that assays for all 3 antibodies are commercially available, and that some centers offer cell-based assays for seronegative cases.Rousseff 2021 diagnostic review
  • NIH Genetic Testing Registry: congenital myasthenic syndromes: This link does not list tests for myasthenia gravis, which has no diagnostic gene test. It lists clinical gene tests for congenital myasthenic syndromes, a separate group of inherited conditions that the German guideline says to consider in antibody-negative myasthenia. NIH does not independently verify submissions or endorse any laboratory.NIH GTR
  • argenx Congenital Myasthenic Syndromes Sponsored Testing Program (drugmaker-sponsored): Sponsored by argenx. No-charge gene panel testing for people in the US suspected of a congenital myasthenic syndrome, performed by Labcorp Genetics. It is not a test for autoimmune myasthenia gravis, and the program page notes that a lack of autoantibodies does not exclude seronegative myasthenia gravis. The page says sponsors may receive de-identified patient data and ordering clinicians' contact details. argenx makes Vyvgart.argenx sponsored testing program
  • NIH's Genetic Testing Registry listed 2 tests for a search of “Myasthenia gravis” on November 12, 2026. NIH does not endorse or verify the labs it lists.

Family screening and referral

Who else in the family

  • NINDS states that myasthenia gravis is not inherited or contagious, though it occasionally occurs in more than 1 member of a family.NINDS
  • NORD says upwards of 5% of affected people may have relatives with myasthenia gravis or other autoimmune disorders.NORD
  • Infants of mothers with the disease may develop transient neonatal myasthenia from about 48 hours after birth, lasting days to weeks.NORD
  • Congenital myasthenic syndromes are genetic; the German guideline notes adult-onset forms are often misdiagnosed as seronegative myasthenia gravis.German guideline
  • NORD notes that thyroid disorders and lupus occur more often in people with myasthenia gravis.NORD

Who to refer to

  • Israel's national guideline strongly recommends referral to a neurologist with neuroimmunology and neuromuscular expertise for all patients.Israel national guideline
  • The German guideline says patients with generalized disease should be treated at least once in an experienced myasthenia center.German guideline
  • In a Melbourne cohort of 110 patients, neurology referral took longer when patients had diplopia or saw an ophthalmologist first.Nguyen 2024 Melbourne cohort
  • In an Alexion-funded US survey, the mean time from seeking care to diagnosis was 15.5 months, longer than from onset to seeking care.Jiang 2025 US patient journey survey
  • In a Polish patient survey, diagnosis took 3 years or longer for 30.9% of 321 respondents, and longer for women than men.Sobierajski 2023 Polish patient survey
  • The German guideline calls for rapid admission to a monitoring or intensive care unit for impending or manifest crisis.German guideline
  • Orphanet lists the disease as ORPHA:589 and maps it to ICD-10 code G70.0.Orphanet cross-references

Find a specialist by state

From the CMS NPI Registry, a public directory of US clinicians by registered specialty. A listing is not an endorsement and says nothing about experience with Myasthenia gravis; patient organizations and academic centers can often name experienced clinicians.

ICD-10-CM codes for Myasthenia gravis

For orders, referrals and prior authorization. Each code is checked daily against NLM's ICD-10-CM service.

G70.00Myasthenia gravis without (acute) exacerbationCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup
G70.01Myasthenia gravis with (acute) exacerbationCurrent in NLM's ICD-10-CM listNLM ICD-10-CM lookup

Once the diagnosis is confirmed

Generalized myasthenia gravis drugs for prescribers4 prescribing guides, side by side: Imaavy, Rystiggo, Vyvgart, Zilbrysq. The page also lists 4 other FDA-approved medicines without a guide yet.Open trials: 117Screen a de-identified patient against every recruiting Myasthenia gravis study on ClinicalTrials.gov.Patient and family pageThe plain-language Myasthenia gravis page, with trials, treatments and help paying.

For the patient: why your doctor ordered this test

Plain language a patient can read or take home.

Your doctor ordered these tests because some of your symptoms can be signs of myasthenia gravis. They include a drooping eyelid, double vision, slurred speech, trouble swallowing and weakness that gets worse with activity. In this condition the immune system blocks the signals that nerves send to muscles.

The first step is usually a blood test for antibodies. Some people with myasthenia gravis have a negative blood test. Your doctor may also order nerve and muscle tests, or hold an ice pack on a drooping eyelid for a few minutes to see whether it lifts. A chest scan checks the thymus, a gland behind the breastbone.

Tell your doctors or health care professionals about every medicine you take, including antibiotics and eye drops. Some medicines can make this kind of weakness worse. Please do not stop a prescribed medicine on your own.

Get emergency help right away if you have trouble breathing or cannot swallow. Myasthenia gravis can be treated, and NINDS says most people with it live to an average life expectancy.

Questions clinicians ask about Myasthenia gravis testing

Which combinations of findings should prompt testing for myasthenia gravis?

In published screening and biopsy studies, the highest yields came from ptosis plus referral for suspected ocular myasthenia (65.8% of 155 consecutive patients referred with ptosis and suspected ocular myasthenia), and from clinical suspicion of myasthenia gravis plus AChR or MuSK antibody testing by fixed cell-based assay (14% of 770 patients tested at a Canadian center that used fixed cell-based assays as first-line testing from 2021 to 2024). Among patients already diagnosed, the most common combination began with onset at age 65 or older, seen in 78.8% of 240 patients with onset at age 65 or older treated at PLA General Hospital from 2003 to 2023. These figures describe study groups, not any one patient's chance of having myasthenia gravis.

What is the first blood test for suspected myasthenia gravis?

The AChR binding antibody comes first; a 2021 review reports it is abnormal in up to 85% of generalized and about 50% of ocular disease. Israel's national guideline then calls for MuSK antibodies if AChR is negative, and LRP4 antibodies in selected double seronegative cases.

How accurate is the ice pack test for myasthenic ptosis?

In a study of 155 consecutive patients, the ice pack test had 86% sensitivity and 79% specificity for ocular myasthenia. When both the ice pack test and single-fiber EMG were negative, the negative predictive value was 94%. Israel's national guideline says the test should not be the primary diagnostic approach.

Does a negative AChR antibody rule out myasthenia gravis?

No; only about 50% of people with ocular myasthenia test positive on radioimmunoassay, according to a 2021 review. In one study, live cell-based assays found clustered AChR antibodies in 19.5% and MuSK antibodies in 8.5% of 82 radioimmunoassay-negative patients. Other studies found lower yields, and the 2021 review calls electrodiagnostic tests the next objective step in a seronegative patient.

How often is myasthenia gravis missed in older adults?

A UK study found AChR antibodies in 0.7% of people aged 75 or older, and only 1 of those 8 had a known diagnosis. No pooled figure for missed cases was found. Four of the other 7 had histories of stroke or transient ischemic attack. A Mayo Clinic Proceedings report describes 2 elderly women first diagnosed with ischemic stroke.

Which drugs can worsen or unmask myasthenia gravis?

The MGFA lists 16 drugs or drug classes, with an addendum on immune checkpoint inhibitors. The Cipro label carries a boxed warning that covers fluoroquinolones, and the magnesium sulfate injection label lists myasthenia gravis as a contraindication. Labels for azithromycin, botulinum toxin and timolol eye drops carry warnings or precautions, and the MGFA also names aminoglycosides, beta blockers, statins and D-penicillamine.

What is the ICD-10 code for myasthenia gravis?

The ICD-10-CM codes are G70.00, myasthenia gravis without (acute) exacerbation, and G70.01, myasthenia gravis with (acute) exacerbation. Both were confirmed in the National Library of Medicine's ICD-10-CM lookup on November 11, 2026.

Sources

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A reference for licensed professionals, checked against its sources on November 11, 2026. It summarizes what the cited guidance says and does not tell anyone how to diagnose or treat a specific patient. Guidelines change; the current guideline and the treating clinician's judgment govern. Trial Friend is an independent information service, not a medical provider.