Differentials
Anxiety and panic attacks
SIGNS / SYMPTOMS
Careful history-taking is required to differentiate these conditions from a pheochromocytoma.
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 pheochromocytoma are episodic in nature.
INVESTIGATIONS
Diagnosis is clinical.
These patients will not have biochemical evidence of hypercatecholaminemia 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 pheochromocytoma, especially in the setting of hypertension.
INVESTIGATIONS
Pheochromocytomas can usually be ruled out with measurement of urine metanephrines, normetanephrines, and catecholamines.
Paroxysmal, drug-resistant hypertension is more suggestive for a pheochromocytoma. In contrast, essential hypertension is drug-responsive and easier to treat.
Hyperthyroidism
SIGNS / SYMPTOMS
May mimic a pheochromocytoma 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 pheochromocytoma 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 pheochromocytoma. Additionally, cocaine can lead to false-positive serum and urine testing for a pheochromocytoma.[2]
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 pheochromocytoma.
Carcinoid syndrome
SIGNS / SYMPTOMS
This syndrome is characterized by periods of intense flushing usually associated with diarrhea, cramping, wheezing, and tricuspid valve and pulmonary valve abnormalities.
Carcinoid tumors are characteristically associated with a dry skin flush; in contrast, pheochromocytomas are associated with pallor.
INVESTIGATIONS
Carcinoid is diagnosed by increased urinary 5-hydroxyindole acetic acid levels, as well as a biopsy of the tumor.
Cardiac arrhythmias
SIGNS / SYMPTOMS
Can also present with symptoms similar to those caused by a pheochromocytoma: namely, palpitations.
Rarely, an underlying pheochromocytoma 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 will be high in a pheochromocytoma and normal in patients with an isolated arrhythmia.
Menopause
SIGNS / SYMPTOMS
Symptoms of menopause may mimic a pheochromocytoma.
Patients commonly complain of profuse sweating and flushing.
In contrast, patients with a pheochromocytoma have profuse sweating associated with pallor.
INVESTIGATIONS
Catecholamines and their metabolites are not elevated during menopause.
Preeclampsia
SIGNS / SYMPTOMS
Typically, presents beyond 20 weeks of pregnancy; therefore, usually not a likely differential in most patients.
Pheochromocytomas present a rare diagnostic and therapeutic challenge in the pregnant woman.[62][63]
Preeclampsia is associated with edema, which is not a feature of a pheochromocytoma.
INVESTIGATIONS
Preeclampsia patients have proteinuria and usually an elevated blood uric acid; these values are usually normal in patients with a pheochromocytoma.
Catecholamines and metanephrines will be high in a pheochromocytoma and normal in preeclampsia.
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