From the Guidelines
For flushing lab work up, I recommend obtaining a complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid function tests (TSH, free T4), and estradiol levels, as these tests can help identify potential underlying causes of flushing such as polycythemia, carcinoid syndrome, pheochromocytoma, or hormonal imbalances 1. When evaluating a patient with flushing symptoms, it is essential to consider various potential causes, including metabolic, endocrine, and cardiovascular conditions.
- The initial lab workup should include a CBC, CMP, TSH, free T4, and estradiol levels to rule out common causes of flushing.
- Additional targeted testing may be necessary based on clinical suspicion, such as 24-hour urine collection for 5-HIAA (for carcinoid syndrome), plasma metanephrines (for pheochromocytoma), and serum tryptase (for mastocytosis) 1.
- It is crucial to time the labs during a flushing episode to correlate the results with the patient's symptoms.
- The basic workup helps rule out common metabolic and endocrine causes of flushing, while the specialized tests target specific conditions known to cause flushing symptoms.
- Early identification of the underlying cause allows for appropriate treatment and management of this often distressing symptom.
- In patients with a high suspicion of mastocytosis, measuring the ratio of total tryptase (a plus b) to b-tryptase can be useful in distinguishing degranulation episodes in patients with mastocytosis from anaphylactic events in patients without this disorder 1.
From the Research
Flushing Lab Workup
To approach flushing lab workup, it's essential to consider the various causes of flushing, which can be categorized into different groups, including:
- Emotional causes
- Systemic or neoplastic disorders, such as VIPoma, carcinoid syndrome, medullary thyroid cancer, mastocytosis, renal cell carcinoma, and pheochromocytoma 2
- Endocrine causes, including menopausal hot flushes 3
- Other conditions, such as rosacea, climacterum, and anaphylaxis 4
Diagnostic Approach
A comprehensive diagnostic work-up is necessary to determine the underlying cause of flushing, including:
- Clinical evaluation, such as taking a thorough history and physical examination 4
- Biological testing, including laboratory studies to exclude serious diagnoses like carcinoid syndrome, pheochromocytoma, and mastocytosis 2, 4
- Imaging testing, which may be necessary to rule out certain conditions, such as medullary carcinoma of the thyroid or pancreatic cell tumor 4
Considerations
When evaluating flushing, a precise systematic approach is needed to exclude potentially serious underlying causes 3. If symptoms are not progressive, the patient should be advised about its apparently benign nature to avoid unnecessary studies or initiating treatments of minimal benefit 3. A thorough investigation should be performed if the flushing is atypical or not clearly associated with a benign underlying process 5.