Differentials
Anxiety and panic attacks
SIGNS / SYMPTOMS
Careful history-taking is required to differentiate these conditions from a phaeochromocytoma.
It is important to assess the patient's mental state, and enquire about phobias and other psychiatric conditions.
Panic attacks and anxiety are often situational, whereas symptoms associated with a phaeochromocytoma are episodic in nature.
INVESTIGATIONS
Diagnosis is clinical.
These patients will not have biochemical evidence of hypercatecholaminaemia when they are not having a panic attack.
Essential or intractable hypertension
SIGNS / SYMPTOMS
The presence of symptoms such as headache, palpitations, and diaphoresis are all suggestive for a phaeochromocytoma, especially in the setting of hypertension.
INVESTIGATIONS
Phaeochromocytomas can usually be ruled out with measurement of urine metanephrines (also known as metadrenalines), normetanephrines (also known as normetadrenaline), and catecholamines.
Paroxysmal, drug-resistant hypertension is more suggestive for a phaeochromocytoma. In contrast, essential hypertension is drug-responsive and easier to treat.
Hyperthyroidism
SIGNS / SYMPTOMS
May mimic a phaeochromocytoma as it is also associated with diaphoresis, palpitations, tremors, and weight loss.
INVESTIGATIONS
Depressed TSH levels support a diagnosis of hyperthyroidism in the setting of an elevated free thyroxine level.
Urinary work-up studies for a phaeochromocytoma would be negative.
Consumption of illicit substances
SIGNS / SYMPTOMS
Certain recreational drugs such as cocaine and amphetamines can cause symptoms similar to those of a phaeochromocytoma. Additionally, cocaine can lead to false-positive serum and urine testing for a phaeochromocytoma.[60]
INVESTIGATIONS
Toxicology or a drug screen may be useful if drug abuse is suspected as catecholamine and metabolite levels may be acutely elevated after consumption of these substances, making it difficult to distinguish from a phaeochromocytoma.
Carcinoid syndrome
SIGNS / SYMPTOMS
This syndrome is characterised by periods of intense flushing usually associated with diarrhoea, cramping, wheezing, and tricuspid valve and pulmonary valve abnormalities.
Carcinoid tumours are characteristically associated with a dry skin flush; in contrast, phaeochromocytomas are associated with pallor.
INVESTIGATIONS
Carcinoid is diagnosed by increased urinary 5-hydroxyindole acetic acid levels, as well as a biopsy of the tumour.
Cardiac arrhythmias
SIGNS / SYMPTOMS
Can also present with symptoms similar to those caused by a phaeochromocytoma: namely, palpitations.
Rarely, an underlying phaeochromocytoma may actually be the precipitant of an arrhythmia (e.g., supraventricular tachycardia, ventricular fibrillation).
INVESTIGATIONS
Negative ECG/telemetry/Holter monitoring while the patient is symptomatic can rule out this diagnosis.
Catecholamines and metanephrines (also known as metadrenalines) will be high in a phaeochromocytoma and normal in patients with an isolated arrhythmia.
Menopause
SIGNS / SYMPTOMS
Symptoms of the menopause may mimic a phaeochromocytoma.
Patients commonly complain of profuse sweating and flushing.
In contrast, patients with a phaeochromocytoma have profuse sweating associated with pallor.
INVESTIGATIONS
Catecholamines and their metabolites are not elevated during the menopause.
Pre-eclampsia
SIGNS / SYMPTOMS
Typically, presents beyond 20 weeks of pregnancy; therefore, usually not a likely differential in most patients.
Phaeochromocytomas present a rare diagnostic and therapeutic challenge in the pregnant woman.[61][62]
Pre-eclampsia is associated with oedema, which is not a feature of a phaeochromocytoma.
INVESTIGATIONS
Pre-eclampsia patients have proteinuria and usually an elevated blood uric acid; these values are usually normal in patients with a phaeochromocytoma.
Catecholamines and metanephrines (also known as metadrenalines) will be high in a phaeochromocytoma and normal in patients with pre-eclampsia.
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