What levels of catecholamines (Catecholamines) are considered abnormal?

From the Guidelines

Abnormal catecholamine levels are typically considered those that exceed the established reference ranges, with values above 100 pg/mL for epinephrine, 600 pg/mL for norepinephrine, and 30 pg/mL for dopamine considered elevated in adults, as supported by recent clinical guidelines 1. When ordering catecholamines, it is essential to consider the potential risks and benefits, particularly in patients with certain medical conditions.

Key Considerations

• Dosages of catecholamines, such as dopamine, should be carefully monitored to avoid potential complications, including vasoconstriction or arrhythmias, with dosages above 20 mcg/kg/min considered potentially problematic 1.
• The effects of catecholamines can vary depending on the dosage, distribution, and metabolism, with lower doses of dopamine (1-2 mcg/kg/min) having a predominantly vasodilatory effect, while higher doses (5-20 mcg/kg/min) can enhance chronotropy and inotropy 1.
• Epinephrine, another catecholamine, has strong alpha-adrenergic and beta-adrenergic stimulatory effects, including increasing chronotropy, inotropy, blood pressure, and myocardial oxygen consumption, with standard dosages for advanced cardiac life support ranging from 2 to 10 mcg/min 1.

Clinical Implications

• Elevated catecholamine levels can indicate conditions such as pheochromocytoma, paraganglioma, neuroblastoma, or severe stress, and may require careful management, including preoperative biochemical screening and adrenoceptor blockade, to avoid rare but catastrophic perioperative complications 1.
• Patients with norepinephrine-producing tumors should be treated with α-adrenoceptor blockade prior to any therapeutic intervention, while those with dopamine-only producing tumors may not require pretreatment with α-adrenoceptor blockers 1.
• The use of metyrosine, which inhibits tyrosine hydroxylase and thereby catecholamine biosynthesis, can be considered as an add-on drug in certain cases, while monotherapy with non-selective β-adrenoceptor blockers is contraindicated due to the risk of eliciting hypertension 1.

From the Research

Abnormal Catecholamine Ordering

When ordering catecholamines, several factors are considered abnormal, including:

• High or low doses of vasopressors, such as norepinephrine, epinephrine, and dopamine, which can have adverse effects on blood pressure and cardiac output 2, 3
• Inappropriate use of inotropes, such as dobutamine and milrinone, which can increase cardiac contractility but also have potential side effects 2
• Failure to consider the patient's underlying pathophysiology of shock, which can lead to suboptimal treatment and adverse outcomes 2

Catecholamine Classification

Catecholamines can be classified into different types, including:

• Vasopressors, which increase blood pressure by constricting blood vessels, such as phenylephrine and vasopressin 2
• Inotropes, which increase cardiac contractility, such as dobutamine and milrinone 2
• Inoconstrictors, which have both inotropic and vasoconstrictive effects, such as dopamine, norepinephrine, and epinephrine 2

Conversion Ratios

Conversion ratios between different vasopressors can be used to calculate equipotent doses, such as:

• Norepinephrine equivalents (NE) can be calculated using a formula that takes into account the doses of different vasopressors, such as epinephrine, dopamine, and phenylephrine 3
• The formula for calculating NE is: NE = norepinephrine + epinephrine + phenylephrine/10 + dopamine/100 + metaraminol/8 + vasopressin2.5 + angiotensin II10 3

Catecholamine Receptors

Catecholamines act on different receptors, including:

• Dopamine receptors, which are involved in various physiological processes, such as motor control, motivation, and reward 4, 5
• Adrenergic receptors, which are involved in the regulation of blood pressure, heart rate, and other physiological processes 4, 6
• The D4 receptor, which is a subtype of dopamine receptor that is involved in affective and emotional behavior, and can be activated by dopamine, epinephrine, and norepinephrine 4