Pompe Disease (GSD II)MANAGEMENT

ENDOCRINE AND METABOLIC PRESENTATIONS · 12 SECTIONS

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645 items

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Endocrine and Metabolic Presentations45▾

Acute Porphyria Adrenal crisis Adrenal Insufficiency (Addisonian Crisis)Dehydration Diabetes Insipidus Diabetic Ketoacidosis (DKA)Euglycemic DKA (SGLT2 inhibitor)Galactosemia GLP-1 receptor agonist complications (retained gastric contents, aspiration risk)Homocystinuria Hypercalcemia Hyperkalemia Hypermagnesemia Hypernatremia Hyperosmolar Hyperglycemic State (HHS)Hypertensive emergency Hypertensive urgency Hypocalcemia Hypoglycemia Hypogonadism (Acute Presentation)Hypokalemia Hypomagnesemia Hyponatremia Hypoparathyroidism (Tetany)Insulin pump failure Maple Syrup Urine Disease (Crisis)Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCAD)Metabolic Acidosis Metabolic Alkalosis Myasthenia gravis crisis Myxedema coma Pellagra Pheochromocytoma (Crisis)Pituitary Apoplexy Pompe Disease (GSD II)Respiratory Acidosis Respiratory Alkalosis Scurvy SIADH Starvation Ketosis Tarui Disease (GSD VII)Thyroid storm Tyrosinemia Vitamin D Deficiency (Severe-Rickets)Von Gierke Disease (GSD I)

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

01Approach to the Critical Patient/attcp46

Immediate priorities

›Life-threatening presentations

›Acute respiratory failure

›Diaphragmatic weakness with sudden decompensation

›Precipitant: respiratory infection, sedation, or anesthesia

›If SpO2 < 90% or rising PaCO2, escalate immediately

›Cardiopulmonary collapse in IOPD

›Hypertrophic cardiomyopathy with LVOT obstruction

›Tachyarrhythmia or sudden death risk with fever, dehydration, or stress

›Secure IV access and continuous cardiac monitoring

›Aspiration risk

›Swallowing dysfunction with laryngeal penetration

›Wet vocal quality or drooling

›NPO and suction at bedside until swallow safety confirmed

Monitoring and targets

›Monitoring bundle

›Continuous pulse oximetry

›SpO2 target >= 94% upright

›Supine SpO2 monitoring for diaphragmatic compromise

›Cardiac monitor

›Arrhythmia detection in IOPD

›QRS morphology for pre-excitation or WPW pattern (if Danon disease in differential)

›Respiratory mechanics

›FVC upright vs supine

›>10% drop supine indicates diaphragmatic weakness

›Escalation triggers

›Declining SpO2 despite supplemental oxygen

›Non-invasive ventilation or HFNC consideration

02History/hx64

Presenting symptoms

›Core symptom complex

›Progressive proximal weakness

›Difficulty climbing stairs or rising from chairs

›Frequent falls

›Respiratory symptoms

›Orthopnea

›Morning headaches indicating nocturnal hypoventilation

›Daytime somnolence

›Dyspnea on exertion

›Exercise intolerance and fatigue

›Rapid deterioration with respiratory infections

›Post-exertional myalgia

Disease onset and timeline

›Age of onset and subtype clues

›IOPD onset within first 3 months of life

›Hypotonia, feeding difficulties, cardiomegaly

›Rapid deterioration without ERT; death in first year if untreated

›LOPD onset any age; mean ~28 years

›18% of LOPD cases present before age 12

›Insidious limb-girdle weakness; legs > arms

›Diagnostic delay average 4.1 years in LOPD

›Irreversible muscle damage during delay

›Prior misdiagnosis as LGMD common

Associated symptoms and review of systems

›Musculoskeletal

›Proximal weakness pattern

›Trendelenburg gait

03Physical Exam/exam56

Vitals and general appearance

›Stability snapshot

›Temperature

›Fever as precipitant for acute decompensation

›Respiratory rate

›Tachypnea at rest or with minimal exertion

›Oxygen saturation

›Room air vs supine value

›Ambulatory desaturation

›Blood pressure

›Hypotension in IOPD cardiomyopathy

›General appearance

›Increased work of breathing

›Paradoxical abdominal breathing indicating diaphragmatic weakness

›Accessory muscle use

›IOPD features

›Profound hypotonia (floppy baby)

›Macroglossia

›Hepatomegaly

Neuromuscular exam

›Proximal muscle assessment

›Hip flexor and hip abductor strength

›Trendelenburg sign

›Gowers' sign for floor to stand

›Neck extensor strength

›Disproportionate weakness common in LOPD

›Paraspinal and scapular stability

›Lumbar lordosis

04Differential Diagnosis/ddx46

Life-threatening mimics

›Immediate threats requiring differentiation

›Danon disease (LAMP2 mutation)

›ICD-10 E74.09

›X-linked HCM with WPW pattern on ECG

›Intellectual disability present

›LAMP2 gene testing distinguishes

›PRKAG2 cardiomyopathy

›HCM with pre-excitation

›Autosomal dominant

›No enzyme deficiency

›GSD III (Cori/Forbes disease)

›ICD-10 E74.03

›Hepatomegaly more prominent

›Can present with HCM

Neuromuscular mimics

›Myopathies

›Limb-girdle muscular dystrophies

›Most common misdiagnosis in LOPD

›Overlap in proximal weakness pattern

›Genetic panel differentiates

›Duchenne or Becker muscular dystrophy

›ICD-10 G71.01

›X-linked; dystrophin deficiency

›Different biopsy and genetic findings

›Polymyositis or inflammatory myopathies

›ICD-10 M33.20

›Elevated CK but inflammatory infiltrate on biopsy

05Laboratory Tests/lt41

Enzyme and confirmatory tests

›GAA enzyme activity (first-line screening)

›Dried blood spot (DBS) preferred initial test

›Tandem mass spectrometry preferred over fluorimetry

›Reduces pseudodeficiency false positives

›Confirmatory testing after abnormal DBS

›GAA activity in leukocytes or fibroblasts

›GAA gene sequencing essential for confirmation

›Pseudodeficiency allele consideration

›Low activity on DBS may be false positive

›Two pseudodeficiency alleles: c.1726G>A and c.2065G>A

›Anti-rhGAA antibody titers

›Monitor in patients on ERT

›Especially critical in CRIM-negative patients

›High-titer antibodies reduce ERT efficacy

›Baseline before initiating ERT

Muscle and metabolic markers

›Serum CK

›Elevated in ~95% of LOPD

›May be normal in some LOPD patients

›Up to 2000 IU/L in IOPD

›CK isoform

›Predominantly MM fraction from skeletal muscle

›Liver enzymes

›AST and ALT elevation from muscle origin not hepatic

›LDH co-elevation

›No hepatocellular injury pattern

›Urinary glucotetrasaccharide (Hex4)

06Diagnostic Tests/dt75

Scoring Systems

›Functional outcome measures

›6-Minute Walk Test (6MWT)

›Standard outcome measure for ERT response monitoring

›Decline in distance correlates with disease progression

›Improvement threshold >20 meters considered clinically meaningful

›Rotterdam Handicap Scale

›Mobility and activities of daily living in LOPD

›Used in clinical trials of ERT

›Quantitative muscle testing

›Dynamometry for hip flexors and knee extensors

›Serial tracking for treatment response

›Respiratory scoring

›FVC supine vs upright

›>10% drop supine predicts diaphragmatic weakness

›FVC < 80% triggers respiratory consultation

›FVC < 50% indicates high risk of respiratory failure

›Maximal inspiratory pressure (MIP) and MEP

›Reflects neuromuscular respiratory reserve

›Serial monitoring at least annually

MRI

›Muscle MRI

›Paraspinal, gluteal, and thigh muscle involvement pattern

›Fatty infiltration on T1-weighted sequences

›Edema-like signal on STIR sequences

›Diagnostic and monitoring utility

›Useful when enzyme/genetic testing inconclusive

›Quantifies disease burden and treatment response

07Disposition/dispo36

Inpatient admission criteria

›Admission indications

›Acute respiratory failure

›SpO2 < 92% on supplemental oxygen

›Rising PaCO2 on ABG in mmHg

›Hemodynamic instability

›IOPD cardiomyopathy decompensation

›Tachyarrhythmia requiring treatment

›Rhabdomyolysis

›Pigmenturia and markedly elevated CK

›IV hydration and renal monitoring required

›Inability to maintain oral intake

›Dysphagia with aspiration risk

›Feeding support planning required

ICU level care

›ICU indications

›Impending or established ventilatory failure

›Non-invasive ventilation or mechanical ventilation requirement

›Airway protection failure

›Cardiac arrest risk in IOPD

›Arrhythmia with hemodynamic compromise

›LVOT obstruction with low output state

›Post-anesthetic complication

›Delayed emergence or prolonged muscle weakness

›Rhabdomyolysis after inappropriate agent use

Transfer and outpatient considerations

›Transfer criteria

›Pediatric Pompe disease requiring specialized pediatric ICU

08Treatment/t103

Enzyme replacement therapy

›First-line ERT: alglucosidase alfa (Lumizyme or Myozyme)

›Standard dosing

›20 mg/kg IV every 2 weeks

›Approved for all Pompe disease subtypes

›Enhanced dosing for IOPD

›40 mg/kg biweekly or weekly at many centers

›Improved survival and motor outcomes demonstrated

›Infusion-associated reactions occur in ~25%

›Antihistamine premedication

›Corticosteroid premedication for prior reactions

›Slow infusion rate for breakthrough reactions

›Next-generation ERT: avalglucosidase alfa (Nexviazyme)

›Dosing

›20 mg/kg IV every 2 weeks for patients <30 kg

›40 mg/kg IV every 2 weeks for patients >=30 kg

›~15-fold higher mannose-6-phosphate content

›Improved muscle uptake compared to alglucosidase alfa

›Approved for LOPD age >= 1 year

›COMET trial demonstrated superiority over alglucosidase alfa

›Combination therapy: cipaglucosidase alfa plus miglustat (Pombiliti plus Opfolda)

›Target population

›Adults with LOPD >= 40 kg not improving on current ERT

›Miglustat is a pharmacological chaperone stabilizing cipaglucosidase alfa

›Dosing

›Cipaglucosidase alfa 20 mg/kg IV every 2 weeks

›Miglustat 260 mg PO 1 hour before infusion

Immunomodulation for CRIM-negative patients

›CRIM-negative Pompe disease management

›Rituximab plus methotrexate plus IVIG protocol

›Rituximab to deplete B cells before ERT initiation

›Methotrexate for ongoing immunosuppression

›IVIG for immunoglobulin replacement

›Goal: prevent high-titer antibody formation

›High-titer anti-GAA antibodies eliminate ERT efficacy

›Class I expert consensus recommendation

›Timing

›Initiate immunomodulation before or concurrent with first ERT dose

Respiratory management

›Non-invasive ventilation

›CPAP or BiPAP for nocturnal hypoventilation

›Initiate when nocturnal SpO2 < 88% or PaCO2 rising

›Titrate to normalize nocturnal capnography

›Daytime NIV when FVC < 50%

›Reduce work of breathing

›Improve gas exchange

›Mechanical ventilation

›Invasive ventilation if NIV fails

›Ketamine or etomidate for induction

›Avoid succinylcholine

›Avoid propofol infusion in IOPD

›Tracheostomy consideration for chronic ventilator dependence

›Multidisciplinary decision

›Patient and family goals of care discussion

›Airway clearance

›Manual assisted cough or mechanical insufflator-exsufflator

›When peak cough flow < 270 L/min

›Chest physiotherapy adjunct

›Pneumococcal and influenza vaccination to reduce respiratory infection

Cardiac management in IOPD

›LVOT obstruction avoidance

›Avoid agents that worsen obstruction

›Digoxin contraindicated

›ACE inhibitors and afterload reducers contraindicated

›Diuretics used cautiously

›Avoid beta-blockers unless specific arrhythmia indication

›Risk of sudden death reported

›Arrhythmia management

›WPW pattern requires electrophysiology consultation

›Risk of sudden death with accessory pathway

›Antiarrhythmic choice by electrophysiology guidance

Anesthesia precautions

›Safe anesthetic agents

›Ketamine

›Maintains SVR and cardiac contractility

›Preferred induction agent in IOPD

›Etomidate

›Hemodynamically stable

›Acceptable alternative

›Agents to avoid

›Succinylcholine contraindicated

›Rhabdomyolysis and hyperkalemia risk

›Volatile anesthetic agents with caution

›Rhabdomyolysis risk

›Malignant hyperthermia precautions

›Propofol in IOPD

›Afterload reduction causing myocardial ischemia

›Deaths reported

Supportive and adjunctive therapies

›Nutritional management

›High-protein low-carbohydrate diet

›2 g/kg/day protein target

›25-30% protein, 30-35% carbohydrate, 35-40% fat ratio

›Adequate caloric intake

›Jaw fatigue and dysphagia risk for inadequate intake

›Soft or pureed texture modification when needed

›Supplementation

›Vitamin D and calcium per neuromuscular disease guidelines

›Bisphosphonate for osteoporosis prevention

›Exercise therapy

›Combined aerobic and resistance training

›Improved peak aerobic power in adults on ERT

›Reduced CK and LDH with exercise plus high-protein diet

›Supervised program adjusted to functional capacity

›Avoid over-exertion causing rhabdomyolysis

›Swallowing rehabilitation

›Speech language pathology involvement

›Videofluoroscopic swallowing study guided

›Diet texture and fluid thickening as needed

09Special Populations/sp55

Pregnancy

›Pregnancy considerations in Pompe disease

›Physiologic changes affecting disease

›Increased abdominal pressure worsens respiratory mechanics

›Diaphragmatic elevation further reduces FVC

›Delayed gastric emptying increases aspiration risk

›ERT safety in pregnancy

›Alglucosidase alfa classified as limited human data

›Generally continued given disease severity risk

›Multidisciplinary decision: maternal-fetal medicine and neuromuscular specialist

›Respiratory monitoring

›FVC serial monitoring each trimester

›Early non-invasive ventilation if FVC declining

›SpO2 target >= 95% for fetal wellbeing

›Delivery planning

›Anesthesia consultation with Pompe disease briefing

›Succinylcholine contraindicated for rapid sequence intubation

›Epidural preferred to reduce anesthetic agent exposure

›Assisted delivery consideration to reduce expulsive effort in weak respiratory muscles

Geriatric

›Older adult features

›LOPD diagnosis in older adults

›Long diagnostic delay common: mean 4.1 years from symptom onset

›Mistaken for age-related sarcopenia or COPD

›Polypharmacy risks

›Renal function adjusted ERT scheduling

›Increased sensitivity to sedating medications

›QT prolongation risk with concomitant medications

10Background/b66

Epidemiology

›Incidence and prevalence

›Estimated incidence 1 in 4,000 to 1 in 350,000 live births

›Wide variation by population and measurement method

›Higher incidence in African American and Chinese populations for IOPD

›LOPD accounts for >80% of all Pompe disease cases

›Exact prevalence unknown due to underdiagnosis

›Over 500 disease-causing GAA variants identified

›Most common variant: c.-32-13T>G IVS1 splicing variant

›Mortality and morbidity

›IOPD untreated: death within first year from cardiorespiratory failure

›ERT dramatically improves survival and motor outcomes

›LOPD: progressive disability over decades

›Respiratory failure leading cause of death

›Wheelchair dependence and ventilator dependence with progression

›Newborn screening programs enable pre-symptomatic diagnosis

›Added to US RUSP (Recommended Uniform Screening Panel) in 2015

Pathophysiology

›Genetic and enzymatic basis

›Autosomal recessive mutations in GAA gene on chromosome 17q25

›GAA encodes acid alpha-glucosidase

›>500 pathogenic variants; most common c.-32-13T>G

›Acid alpha-glucosidase deficiency

›Enzyme normally degrades glycogen in lysosomes

›Deficiency leads to glycogen accumulation within lysosomes

›IOPD: near-complete enzyme deficiency (<1% residual activity)

›Rapid glycogen accumulation in cardiac and skeletal muscle

›LOPD: partial enzyme deficiency (1-30% residual activity)

11Patient Discharge Instructions/pdi36

copy discharge instructions

›Pompe disease home care instructions

›Continue all prescribed medications without interruption

›Do not miss ERT infusion appointments

›Contact infusion center if unable to attend

›Diet recommendations

›High-protein diet as recommended by care team

›Small frequent meals if jaw fatigue limits large meals

›Use recommended food texture if swallowing is difficult

›Activity

›Participate in recommended physiotherapy and exercise program

›Avoid extreme exertion that causes muscle pain or dark urine

›Respiratory equipment

›Use prescribed CPAP or BiPAP every night

›Contact care team if machine not tolerated or not helping

›Warning signs to return to emergency department

›Difficulty breathing at rest or when lying flat

›Cannot speak in full sentences

›Blue lips or fingernails

›Rapid heart rate or irregular heartbeat

›Especially in infants with known cardiomyopathy

›Dark brown or red urine

›May indicate muscle breakdown (rhabdomyolysis)

›Severe muscle pain that does not resolve with rest

›Choking on food or liquids

›Aspiration risk

›Worsening weakness over days

›New inability to walk, stand, or lift arms

12References/r21

Guidelines and key sources

›Society and clinical guidelines

›European recommendations for Pompe disease management

›Cupler EJ et al. Consensus treatment recommendations for late-onset Pompe disease

›Orphanet Journal of Rare Diseases

›ACMG newborn screening guidelines

›American College of Medical Genetics and Genomics

›Pompe disease added to US RUSP 2015

›Muscular Dystrophy Association clinical guidelines for Pompe disease

›Key clinical trials

›COMET trial (NEJM 2022)

›Avalglucosidase alfa vs alglucosidase alfa in treatment-naive LOPD

›Superiority in 6MWT and FVC demonstrated

›Alglucosidase alfa LOPD pivotal trial (NEJM 2010)

›Improvement in 6MWT and FVC vs placebo

›Class I evidence for ERT in LOPD

›IOPD natural history studies

›van den Hout et al.; early ERT dramatically improves survival

›Coding and classification

›ICD-10 E74.02 Pompe disease (acid maltase deficiency)

›SNOMED CT concept for glycogen storage disease type II

›OMIM 232300 Pompe disease entry

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Reviewed by SymptomDx Medical Team · Last reviewed August 18, 2026

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