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Approach to the Critical Patient
Immediate priorities
Life threats in acute attack
Airway and ventilation failure
Bulbar weakness with poor secretion clearance
Intercostal and diaphragmatic weakness
If declining vital capacity, prepare intubation
Status epilepticus
Seizures in ~20% of acute attacks
Often driven by hyponatremia or hypomagnesemia
If seizing, IV magnesium sulfate and benzodiazepine first line
Severe hyponatremia
SIADH in ~40% of attacks
Risk of precipitous fall with hypotonic fluids
If symptomatic, controlled correction with isotonic strategy
Recognition triggers
Purple flag triad
Abdominal pain plus seizures plus hyponatremia
Young woman of reproductive age
Highly suggestive of acute hepatic porphyria
Pain and exam discordance
Severe diffuse pain with benign abdomen
Normal abdominal imaging despite symptoms
Recurrent nondiagnostic presentations
Prior negative surgical workups
Prior psychiatric labeling
Immediate actions
First moves on suspicion
Stop all porphyrinogenic drugs immediately
Barbiturates and anticonvulsant inducers
Sulfonamides and rifampin
Progesterone-containing agents
Collect random urine before therapy
Urine PBG, ALA, and creatinine
Send prior to first hemin dose
Start carbohydrate loading
IV 10% dextrose in 0.45% saline
Avoid dextrose in water to prevent hyponatremia
Escalation triggers
ICU transfer indications
Respiratory compromise or bulbar signs
Status epilepticus
Progressive motor neuropathy
Specialist activation
Porphyria specialist or hepatology
Neurology for seizures or weakness
Monitoring and targets
Monitoring bundle
Continuous cardiac and oximetry
Tachycardia from autonomic overactivity
QT risk with electrolyte derangement
Serial electrolytes
Sodium trend every 4 to 6 hours when abnormal
Magnesium repletion targets
Respiratory mechanics
Vital capacity trend
Negative inspiratory force trend
Treatment targets
Pain control adequacy
Opioid titration to comfort
Reassess sedation and ventilation
Biochemical response
Falling urine PBG by day 3 of hemin
Clinical improvement by day 4
History
Presenting symptoms
Core neurovisceral syndrome
Severe diffuse abdominal pain
Present in ~90% of attacks
Colicky and poorly localized
Radiation to back or thighs
Gastrointestinal features
Nausea and vomiting
Constipation from ileus
Urine changes
Dark, reddish, or tea-colored
May darken only on standing in light
Neuropsychiatric features
Motor symptoms
Limb pain and weakness
Proximal greater than distal
Psychiatric symptoms
Anxiety and agitation
Confusion or hallucinations
Seizures
May be presenting event
Often electrolyte related
Triggers and timeline
Attack triggers
Medication changes
CYP450 and ALAS1 inducers
Recent new prescriptions
Caloric deprivation
Fasting or crash diets
Recent bariatric surgery
Hormonal and lifestyle
Luteal phase catamenial attacks
Alcohol and smoking
Infection or psychological stress
Temporal pattern
Prodrome
Fatigue and poor concentration
Insomnia for days before pain
Attack duration
Typically 1 to 2 weeks
Gradual resolution with treatment
Risk factors and family history
Personal risk profile
Female reproductive age
80 to 90% of symptomatic patients
Hormonal fluctuation sensitivity
Prior attack history
Recurrent unexplained abdominal pain
Repeated nondiagnostic ED visits
Family and genetic context
Autosomal dominant inheritance
Low penetrance, many asymptomatic carriers
Absent family history does not exclude
Relatives with suggestive features
Unexplained abdominal pain
Psychiatric symptoms or neuropathy
Physical Exam
Vital signs and general
Autonomic findings
Tachycardia
Sympathetic overactivity in most attacks
Persistent despite analgesia
Hypertension
Often coexisting with tachycardia
May be labile
Diaphoresis and retention
Sweating
Urinary retention
General appearance
Distress out of proportion
Severe pain with benign abdomen
Restlessness and anxiety
Mental status
Agitation or confusion
Hallucinations in some
Abdominal exam
Discordant abdominal findings
Absent peritoneal signs
No rebound
No guarding or rigidity
Ileus signs
Mild distension
Decreased bowel sounds
Neurologic and skin exam
Neurologic findings
Motor weakness
Proximal and arms greater than legs
Can progress to quadriparesis
Reflexes and sensation
Reduced or absent deep tendon reflexes
Dysesthesias and paresthesias
Respiratory effort
Intercostal weakness as warning sign
Weak cough and secretion pooling
Skin and urine
Photosensitive lesions
Blistering on sun-exposed areas
Seen in variegate and hereditary coproporphyria only
Urine appearance
May look normal when fresh
Darkens to reddish-brown on standing
Differential Diagnosis
Surgical and life-threatening mimics
Acute surgical abdomen
Appendicitis or cholecystitis
Peritoneal signs present
Positive imaging findings
Bowel obstruction
Distension with obstructive imaging
ICD-10 K56.60 unspecified obstruction
Endocrine and metabolic emergencies
Addisonian crisis
Hyponatremia and hypotension
Abdominal pain overlap
Lead poisoning
Abdominal pain with elevated urine ALA
Normal PBG and anemia present
Neurologic mimics
Guillain-Barre syndrome
Ascending weakness
Elevated CSF protein
Normal urine PBG
Distinguishing tests
Nerve conduction patterns
CSF albuminocytologic dissociation
Other porphyria-related conditions
Tyrosinemia type 1
Elevated ALA without PBG elevation
Hepatic dysfunction in children
Other acute hepatic porphyrias
Variegate and hereditary coproporphyria
Differentiated by urine and stool porphyrins
Psychiatric and functional overlap
Functional and behavioral labels
Functional abdominal pain
Benign exam and poor opioid response
Frequent misdiagnosis
Drug-seeking attribution
Repeated opioid requests
Risk of missed true diagnosis
Coding references
Acute intermittent porphyria
ICD-10 E80.21
SNOMED CT acute intermittent porphyria disorder
Hereditary coproporphyria and variegate
ICD-10 E80.20 other and unspecified porphyria
Subtype confirmed biochemically
Laboratory Tests
Diagnostic biochemistry
First-line screening
Random urine PBG
Normalized to creatinine
Elevated at least 5-fold in attack
Often 10 to 150 times upper limit
Random urine ALA
Elevated alongside PBG
Distinguishes lead and tyrosinemia when PBG normal
Sample handling
24-hour collection not required
Protect specimen from light
Subtyping and confirmation
Urine porphyrin fractionation
Helps subtype after positive PBG
Not a standalone screen due to false positives
Genetic testing
HMBS for acute intermittent porphyria
CPOX, PPOX, ALAD for other subtypes
Supportive labs
Electrolytes and organ panels
Basic metabolic panel
Hyponatremia in ~40%
Hypomagnesemia
Liver function
Mild transaminase elevation
Baseline for surveillance
Renal function
Baseline creatinine and eGFR
Chronic kidney disease as late complication
Hematology and exclusion
Complete blood count
Usually normal
Anemia suggests lead poisoning instead
Infection screen when febrile
Cultures if sepsis suspected
Identify precipitating infection
Treatment monitoring labs
On hemin therapy
Iron studies and ferritin
Iron overload with repeated dosing
Monitor with prophylactic infusions
Coagulation awareness
Transient anticoagulant effect of hemin
Monitor with concurrent risk
On givosiran prophylaxis
Hepatic and renal monitoring
CMP and protein-to-creatinine ratio
Amylase and lipase
Metabolic monitoring
Homocysteine
B12 and folate
Diagnostic Tests
Scoring Systems
Severity stratification
Mild attack
Pain manageable without opioids
No hyponatremia, seizures, or weakness
Outpatient carbohydrate loading candidate
Moderate to severe attack
Requires opioids
Hyponatremia, seizures, or motor neuropathy
Admission and IV hemin
Life-threatening attack
Respiratory or bulbar compromise
Severe encephalopathy or status epilepticus
ICU admission
Purple flag criteria
Clinical trigger set
Abdominal pain prompting opioids
Hyponatremia
Recurrent nondiagnostic presentations
Diagnostic action
Prompt urine PBG testing
Avoid empirical surgery
MRI
Brain MRI
Indications
Encephalopathy or seizures
Unexplained altered mental status
Characteristic finding
Posterior reversible encephalopathy syndrome
Reversible with attack treatment
Interpretation
Not specific to porphyria
Supports severity assessment
Limitations
Diagnostic role
Does not confirm porphyria
Diagnosis remains biochemical
Practical constraints
Unstable patient access
Implant compatibility
CT
Abdominal CT
Indications
Exclude surgical pathology
Severe pain with diagnostic uncertainty
Typical findings
Normal study
Nonspecific ileus
Diagnostic clue
Imaging normal despite severe pain
Discordance supports porphyria
Head CT
Indications
New seizure or focal deficit
Exclude hemorrhage before MRI
Limitations
Often normal in attack
Not diagnostic of porphyria
Ultrasound
Abdominal ultrasound
Acute role
Exclude biliary and surgical causes
Typically normal or nonspecific
Bedside utility
Rapid surgical screen
Avoids radiation in young women
Liver surveillance ultrasound
Indication
Hepatocellular carcinoma screening
Begin around age 50 or after prolonged activity
Frequency
Annual surveillance
Even without cirrhosis
Disposition
Admission and level of care
Admit indications
Pain requiring opioids
Inadequate oral control
Need for IV analgesia
Metabolic or neurologic involvement
Hyponatremia
Seizures or motor weakness
Therapy and intake needs
Requirement for IV hemin
Inability to maintain oral intake
ICU indications
Respiratory and bulbar
Respiratory compromise
Bulbar signs
Neurologic emergencies
Status epilepticus
Declining vital capacity
Severe hypertension
Hypertensive crisis
Associated PRES
Discharge and follow-up
Discharge criteria
Symptom control
Pain controlled without opioids
No progressive neurologic deficits
Physiologic stability
Stable electrolytes
Adequate oral caloric intake
Specialist follow-up
Timing
Porphyria specialist within 1 to 2 weeks
Neurology if residual deficits
Family and genetic
Genetic counseling
Cascade testing of relatives
Treatment
Initial stabilization
Remove precipitants
Discontinue porphyrinogenic drugs
Barbiturates and inducing anticonvulsants
Sulfonamides, rifampin, progestins
Treat triggers
Infection management
Correct fasting state
Carbohydrate and fluid therapy
IV dextrose
10% dextrose in 0.45% saline
Approximately 300 to 400 g glucose per day
Avoid hypotonic dextrose in water
Electrolyte correction
Controlled correction of hyponatremia
IV magnesium sulfate for hypomagnesemia
Specific therapy
IV hemin (hematin)
Indication
Moderate to severe attack
First-line specific therapy
Dosing
3 to 4 mg/kg IV once daily
Infuse over 30 to 40 minutes
Course of 3 to 5 days
Administration precautions
Reconstitute with human albumin for stability
Large peripheral vein or central line, PICC preferred
Do not exceed 6 mg/kg in 24 hours
Response expectations
Urine PBG falls by day 3
Clinical improvement by day 4
Glucose-only bridge
Indication
Mild attack
Bridge until hemin available
Dosing
IV 10% dextrose 300 to 400 g per day
Escalate to hemin if no improvement
Symptom management
Analgesia and antiemetics
Safe analgesics
Opioids such as morphine or fentanyl
Acetaminophen for adjunct
Safe antiemetics
Ondansetron
Chlorpromazine for agitation
Seizure management
Safe agents
IV magnesium sulfate
Benzodiazepines such as lorazepam
Levetiracetam for maintenance
Agents to avoid
Barbiturates and phenytoin
Carbamazepine and valproic acid
Autonomic control
Hypertension and tachycardia
Beta-blockers when needed
Treat underlying attack
Avoid porphyrinogenic agents
Check drug safety database first
porphyria.org reference
Prophylaxis for recurrent attacks
Pharmacologic prophylaxis
Givosiran
2.5 mg/kg subcutaneous monthly
siRNA targeting hepatic ALAS1 mRNA
For 4 or more attacks per year
Prophylactic hemin
Weekly or biweekly infusions
Monitor for iron overload
Hormonal and definitive options
Catamenial attacks
GnRH agonists
Suppress luteal-phase trigger
Refractory disease
Liver transplantation curative
Reserved for intractable failure of therapy
Special Populations
Pregnancy
Risk and presentation
Attack risk
Progesterone surge as trigger
Hyperemesis and fasting precipitants
Diagnostic approach
Urine PBG remains screening test
Prefer ultrasound to limit radiation
Management adjustments
Therapy safety
IV hemin considered safe in pregnancy
Glucose loading and opioids acceptable
Givosiran caution
Limited pregnancy data
Specialist-guided decision
Geriatric
Presentation differences
Atypical features
Confusion as prominent symptom
Overlap with other comorbidity
Complication burden
Chronic kidney disease
Hypertension and hepatocellular risk
Management considerations
Medication review
Higher polypharmacy and inducer exposure
Renal dose adjustment
Surveillance priority
Annual liver ultrasound
Blood pressure and renal monitoring
Pediatrics
Presentation in children
Rarity before puberty
Attacks uncommon before adolescence
Consider after pubertal onset
Diagnostic overlap
Differentiate tyrosinemia and lead
Use ALA and PBG patterns
Management adjustments
Weight-based therapy
IV hemin 3 to 4 mg/kg/day
Dextrose loading scaled to weight
Family screening
Genetic counseling for family
Cascade testing at-risk siblings
Background
Epidemiology
Disease burden
Subtype frequency
Acute intermittent porphyria most common
Prevalence about 1 in 100,000
Demographic pattern
80 to 90% women of reproductive age
Frequently misdiagnosed
Classification
Acute hepatic porphyria subtypes
Acute intermittent porphyria
Variegate and hereditary coproporphyria
ALA dehydratase deficiency porphyria
Penetrance
Low clinical penetrance
Most carriers asymptomatic
Pathophysiology
Heme synthesis defect
Enzyme deficiency
Partial block in heme biosynthesis
Subtype-specific enzyme defect
Precursor accumulation
ALA and PBG buildup
Presumed neurotoxic effect
Attack mechanism
ALAS1 upregulation
Triggered by inducers and fasting
Drives precursor overproduction
Systemic consequences
Autonomic and motor neuropathy
SIADH causing hyponatremia
Therapeutic Considerations
Mechanistic targets
Suppress ALAS1
Glucose loading effect
Hemin negative feedback
RNA interference
Givosiran reduces ALAS1 mRNA
Lowers ALA and PBG production
Treatment principles
Early treatment priority
Hemin ineffective for established nerve damage
Timely therapy limits irreversible neuropathy
Trigger avoidance
Consult drug safety databases
Maintain caloric intake
Patient Discharge Instructions
copy discharge instructions
Diagnosis and condition
You have acute porphyria
An inherited problem with heme production
Attacks can be triggered by certain drugs and fasting
Carry identification
Medical alert card or bracelet
Tell all providers before surgery or anesthesia
Daily prevention
Avoid triggers
No alcohol or smoking
Do not fast or use crash diets
Medication safety
Check porphyria.org before new medicines
Maintain carbohydrate intake during illness
Return to the ER for
Severe symptoms
Recurrence of severe abdominal pain
New weakness in arms or legs
Seizures or confusion
Other warning signs
Dark or red urine
Inability to eat or drink
Follow-up plan
Specialist care
Porphyria specialist within 1 to 2 weeks
Genetic counseling for family
Ongoing monitoring
Annual liver ultrasound and blood tests
Blood pressure and kidney checks
References
Guidelines and key sources
Clinical practice guidelines
AGA Clinical Practice Update on Acute Hepatic Porphyrias 2023
Diagnosis and management expert review
Random urine PBG as screening test
Recommendations for Diagnosis and Treatment of Acute Porphyrias
Anderson et al, Annals of Internal Medicine 2005
Hemin and glucose protocols
Landmark reviews
Porphyria review
Bissell, Anderson, Bonkovsky, NEJM 2017
Neurovisceral attack pathophysiology
Purple Flags clinical features
Anderson et al, Am J Med Sci 2022
Triggers for specific diagnostic testing
Drug safety and coding
Drug safety databases
porphyria.org and drugs-porphyria.org
Screen before prescribing
Coding standards
ICD-10 E80.21 acute intermittent porphyria
SNOMED CT acute hepatic porphyria concept
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.