Top 24 Differential Diagnosis for a 14-year-old female, not pregnant, with typical or atypical symptoms of Blackouts, Dizziness, Severe Aches And Pains
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Top 24 Differential Diagnoses
Patient: 14-year-old female, non-pregnant
Presenting symptoms: Blackouts (transient loss of consciousness), dizziness, severe aches and pains
This triad spans neurological, cardiovascular, autonomic, rheumatological, metabolic, psychiatric, and haematological domains. Diagnoses are organised by category and ranked roughly by frequency/clinical priority for this demographic.
CATEGORY 1 - Neurally Mediated / Autonomic (Most Common in This Age Group)
1. Vasovagal Syncope (Neurocardiogenic Syncope)
The most common cause of blackouts in adolescents, with peak incidence between ages 10-30 and a median peak around 15 years, higher in females. Triggered by prolonged standing, heat, pain, or emotional stress. Classic prodrome: lightheadedness, nausea, pallor, diaphoresis, visual dimming. Aches can follow post-syncopal muscle soreness. - Harrison's Principles of Internal Medicine 22E, p. 199
2. Postural Orthostatic Tachycardia Syndrome (POTS)
Disproportionate heart rate rise (>30 bpm) on standing without hypotension. Predominates in adolescent females. Causes chronic dizziness, pre-syncope/syncope, and widespread musculoskeletal pain (described as "aching all over"). Often labelled as chronic fatigue or fibromyalgia before diagnosis. Strongly associated with hypermobility syndromes (Ehlers-Danlos).
3. Orthostatic Hypotension
Systolic BP drop of ≥20 mmHg or diastolic ≥10 mmHg on standing. Can occur with dehydration, poor fluid intake (common in teenage girls), autonomic dysfunction, anaemia, or adrenal insufficiency. Produces dizziness and blackouts on standing, with generalised weakness and aching. - ROSEN's Emergency Medicine, p. 146
4. Situational Syncope
A subtype of reflex syncope triggered by specific acts: coughing, swallowing, urination, defecation, exercise. Often overlooked in adolescents. Can be accompanied by post-ictal aching and post-syncopal fatigue.
CATEGORY 2 - Cardiac
5. Cardiac Arrhythmia (Long QT Syndrome / Wolff-Parkinson-White / SVT)
Tachydysrhythmias and bradydysrhythmias can all produce syncope. Long QT syndrome (congenital or drug-induced) is a critical diagnosis not to miss - sudden blackout with no prodrome, often triggered by exercise or startle, may precede sudden cardiac death. Chest discomfort/palpitations may accompany aches. ECG is mandatory. - ROSEN's Emergency Medicine, Box 11.1
6. Hypertrophic Cardiomyopathy (HCM)
Structural cause of cardiac syncope in young athletes. Exertional syncope or pre-syncope with chest pain, dyspnoea, and post-exertional aches. Family history of sudden death is a red flag. Loud ejection systolic murmur, worse on Valsalva. - Fuster and Hurst's The Heart, 15th Ed.
7. Pulmonary Hypertension
Exertional syncope, dizziness, and diffuse joint/chest aching. Can be idiopathic (more common in young females) or secondary to connective tissue disease (especially SLE). Progressive dyspnoea on exertion with loud P2.
CATEGORY 3 - Neurological / CNS
8. Epilepsy / Seizure Disorder (Generalised or Partial)
Post-ictal confusion, headache, and severe whole-body myalgia are classic after tonic-clonic seizures and are commonly misidentified as blackouts rather than seizures. Partial (focal) seizures can cause episodes of dizziness, déjà vu, and altered consciousness with pain. EEG is diagnostic. - Bradley and Daroff's Neurology in Clinical Practice
9. Vestibular Migraine (Migrainous Vertigo)
Leading cause of recurrent dizziness and blackout-like episodes in adolescent females. Migraine is responsible for ~31% of paediatric dizziness presentations. Episodes of severe vertigo, dizziness, and headache, accompanied by widespread musculoskeletal pain. Family history of migraine common. - Scott-Brown's Otorhinolaryngology, p. 265
10. Benign Paroxysmal Vertigo of Childhood/Adolescence
Recurrent brief episodes of severe vertigo without hearing loss. Found in up to 35% of children with dizziness. Closely related to migraine - up to 50% develop migraine in adolescence. Sudden onset, pallor, sweating, nystagmus during attacks, then full recovery. - Scott-Brown's Otorhinolaryngology, p. 265
11. Vertebrobasilar Insufficiency / Posterior Circulation TIA
Dizziness, ataxia, diplopia, dysarthria, and syncope arising from posterior circulation compromise. In adolescents, consider arterial dissection (trauma, hypermobility), migraine-induced vasospasm, or congenital vascular anomaly. Neck pain is a cardinal feature.
CATEGORY 4 - Rheumatological / Inflammatory
12. Systemic Lupus Erythematosus (SLE)
Highly relevant for a 14-year-old female. SLE causes severe polyarthralgia/arthritis, fatigue, serositis, and can produce neuropsychiatric manifestations (seizures, cerebritis) causing blackouts. Autonomic dysfunction in SLE leads to dizziness. Anti-dsDNA, ANA, complement levels (C3/C4) should be checked. Classic butterfly rash may or may not be present.
13. Juvenile Idiopathic Arthritis (JIA) - Systemic or Polyarticular
Severe joint pain and systemic inflammation in adolescents. Systemic JIA with macrophage activation syndrome can cause dramatic multi-system involvement including CNS features. Dizziness and syncope can occur secondary to anaemia of chronic disease and fever-driven haemodynamic changes. Also listed as a cause of childhood vertigo - Scott-Brown's, p. 266.
14. Fibromyalgia
Common in adolescent females (peak onset 13-15 years). Hallmark: widespread musculoskeletal pain at ≥11 of 18 tender points, severe fatigue, dizziness, cognitive fog ("fibro fog"), and sleep disturbance. Autonomic dysregulation causes near-syncope and orthostatic intolerance. Frequently co-exists with POTS.
15. Hypermobility Spectrum Disorder / Ehlers-Danlos Syndrome (hEDS)
Connective tissue laxity produces joint pain, easy bruising, skin hyperextensibility, and importantly - autonomic dysfunction (POTS, orthostatic hypotension), recurrent dizziness, and syncope. A massively underdiagnosed triad in young females presenting with exactly this symptom cluster.
CATEGORY 5 - Haematological / Metabolic
16. Iron Deficiency Anaemia
Extremely common in adolescent girls (menstrual losses). Severe anaemia reduces cerebral oxygen delivery causing blackouts, persistent dizziness, palpitations, and diffuse aching weakness. Check FBC, ferritin, serum iron.
17. Hypoglycaemia
Dizziness, sweating, confusion, and blackout occurring in fasting states or post-exercise. Severe hypoglycaemia causes whole-body tremor and aching. Consider insulin-secreting tumours (insulinoma - rare) or reactive hypoglycaemia (common in adolescents with erratic eating). Also suspect eating disorders.
18. Thyroid Dysfunction (Hypothyroidism / Hyperthyroidism)
- Hypothyroidism: diffuse myalgia, fatigue, slowed reflexes, dizziness, and exercise intolerance (blackouts on exertion).
- Hyperthyroidism/Thyrotoxicosis: palpitations, heat intolerance, proximal muscle weakness, and syncope from tachyarrhythmias. Both are more common in females.
19. Adrenal Insufficiency (Addison's Disease)
Chronic fatigue, severe widespread myalgia, postural dizziness/blackout, salt craving, weight loss, and hyperpigmentation. Life-threatening if missed. Serum cortisol and ACTH stimulation test confirm diagnosis.
20. Electrolyte Disturbance (Hyponatraemia / Hypokalaemia / Hypocalcaemia)
All produce dizziness, muscle cramps and aching, and can cause blackouts/seizures. Hypokalaemia (from purging, laxative abuse, diuretics, or Bartter syndrome) is relevant in a teenage girl. Hypocalcaemia causes tetany, tingling, muscle pain, and syncope.
CATEGORY 6 - Infectious / Post-Infectious
21. Viral Vestibular Neuritis / Labyrinthitis
Acute-onset severe vertigo, dizziness, nausea/vomiting following a viral upper respiratory infection. No hearing loss (neuritis) or with hearing loss (labyrinthitis). Post-infectious fatigue and myalgia persist for weeks. - ROSEN's Emergency Medicine, Table 15.2
22. Post-COVID Syndrome / Long COVID
Recognised cause of multi-system symptoms in adolescents: POTS-like autonomic dysfunction, recurrent dizziness and pre-syncope, severe widespread myalgia, fatigue, and cognitive impairment. Onset 4-12 weeks after acute COVID-19 infection.
CATEGORY 7 - Psychiatric / Functional
23. Functional Neurological Symptom Disorder (FND) / Dissociative Attacks
Attacks mimicking syncope or seizures without cardiovascular or EEG correlate. Common in adolescent females under psychosocial stress. Often associated with chronic diffuse pain, dizziness, and fatigue. Positive clinical signs (Hoover sign, entrainment) help differentiation. NOT a diagnosis of exclusion - it has positive features.
24. Eating Disorder (Anorexia Nervosa / Bulimia Nervosa)
A 14-year-old female with blackouts, dizziness, and severe aching must be screened for eating disorders. Mechanisms include: starvation-induced hypoglycaemia, electrolyte disturbance (hypokalaemia, hypomagnesaemia from purging), severe anaemia, QTc prolongation, and orthostatic hypotension from dehydration. Lanugo, parotid hypertrophy, erosion of dental enamel, low BMI, or amenorrhoea are clues.
Summary Table
| # | Diagnosis | Key Discriminators |
|---|---|---|
| 1 | Vasovagal syncope | Prodrome, triggers, most common |
| 2 | POTS | HR rise on standing, female, widespread pain |
| 3 | Orthostatic hypotension | BP drop on standing, dehydration |
| 4 | Situational syncope | Specific triggers (cough, micturition) |
| 5 | Cardiac arrhythmia (Long QT/WPW/SVT) | No prodrome, exertional, family history of SCD |
| 6 | Hypertrophic cardiomyopathy | Exertional syncope, systolic murmur |
| 7 | Pulmonary hypertension | Exertional dyspnoea, loud P2 |
| 8 | Epilepsy | Post-ictal myalgia, tongue bite, urinary incontinence |
| 9 | Vestibular migraine | Headache, photophobia, family history |
| 10 | Benign paroxysmal vertigo | Brief self-limiting attacks, nystagmus |
| 11 | Vertebrobasilar insufficiency | Diplopia, dysarthria, ataxia, neck pain |
| 12 | SLE | Rash, arthritis, renal involvement, ANA positive |
| 13 | Juvenile idiopathic arthritis | Joint swelling, systemic features, anaemia |
| 14 | Fibromyalgia | Tender points, sleep disturbance, no inflammation |
| 15 | hEDS / Hypermobility | Joint laxity, soft skin, recurrent dislocations |
| 16 | Iron deficiency anaemia | Pallor, menstrual history, low ferritin |
| 17 | Hypoglycaemia | Fasting/exertional, sweating, improves with food |
| 18 | Thyroid dysfunction | TSH, weight change, heart rate abnormality |
| 19 | Adrenal insufficiency | Hyperpigmentation, salt craving, low cortisol |
| 20 | Electrolyte disturbance | Cramps, tetany, purging behaviour |
| 21 | Viral vestibular neuritis | Acute post-viral vertigo |
| 22 | Long COVID / Post-viral syndrome | Recent COVID, POTS-like features |
| 23 | Functional neurological disorder | Positive signs, psychosocial stress, normal tests |
| 24 | Eating disorder | Low BMI, purging, electrolyte abnormalities |
Recommended Initial Investigations
- Bloods: FBC, ferritin, CRP/ESR, U&E, Ca/Mg/PO4, glucose, TFTs, LFTs, ANA/anti-dsDNA, cortisol
- ECG: 12-lead (QTc interval, delta waves, PR interval, Brugada pattern)
- Orthostatic vitals: Active stand test or 10-minute tilt (heart rate and BP at 1, 3, 5, 10 min)
- Urine: Dipstick (protein for SLE), HCG (confirm non-pregnant)
- Neurology: EEG if seizure suspected; MRI brain if focal neurological signs
- Cardiology referral if no prodrome, exertional syncope, or family history of SCD
- Eating disorder screen: SCOFF questionnaire, weight trend, electrolytes
Key red flags requiring urgent cardiology review: exertional syncope, no prodrome, family history of sudden cardiac death under 40, abnormal ECG, syncope during swimming or during startle.
Sources: Harrison's Principles of Internal Medicine 22E; ROSEN's Emergency Medicine; Scott-Brown's Otorhinolaryngology; Fuster and Hurst's The Heart 15th Ed.; Bradley and Daroff's Neurology in Clinical Practice; Wang C et al. Guidelines for neurally mediated syncope in children, World J Pediatr 2024 (PMID 39110332); Russo V et al. Pediatric reflex syncope, Eur J Pediatr 2026 (PMID 41781566).
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