Synonym/Acronym:
BNP and proBNP.
Rationale
To assist in diagnosing and managing heart failure (HF).
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
Method: Chemiluminescent immunoassay for BNP; electrochemiluminescent immunoassay for proBNP; enzyme-linked immunosorbent assay for galectin-3 and soluble ST–2.
BNP | Conventional Units | SI Units (Conventional Units × 1) | |||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Male and Female | Less than 100 pg/mL | Less than 100 ng/L | |||||||||||||||||||||||||||||||||||||||
proBNP (N-terminal) | |||||||||||||||||||||||||||||||||||||||||
0–74 yr | Less than 125 pg/mL | Less than 125 ng/L | |||||||||||||||||||||||||||||||||||||||
Greater than 75 yr | Less than 449 pg/mL | Less than 449 ng/L | |||||||||||||||||||||||||||||||||||||||
BNP levels are increased in older adults. |
Galectin-3 | |
2–17 yr | Less than or equal to 25 ng/mL |
Adult | Less than or equal to 22.1 ng/mL |
Risk Category | |
Low | Less than or equal to 17.8 ng/mL |
Intermediate | 17.9–25.9 ng/mL |
Elevated | Greater than 25.9 mg/mL |
Soluble ST–2 | |
2–17 yr (males and females) | Less than 43 ng/mL |
Adult | |
Male | Less than 52 ng/mL |
Female | Less than 38.7 ng/mL |
Critical Findings and Potential Interventions
N/A
(Study type: Blood collected in a lavender-top [EDTA] tube for B-type natriuretic peptide [BNP], plain red-top tube for galectin-3 and soluble ST-2; related body system: Circulatory system.)
The peptides BNP and atrial natriuretic peptide (ANP) are antagonists of the renin-angiotensin-aldosterone system; they assist in the regulation of electrolytes (e.g., BNP inhibits reabsorption of sodium by the kidneys), fluid balance (e.g., increases glomerular filtration rate, thereby increasing urinary excretion), and blood pressure. BNP, proBNP, and ANP are useful markers in the diagnosis of heart failure (HF). BNP, first isolated in the brain of pigs, is a neurohormone synthesized primarily in the ventricles of the human heart in response to increases in ventricular pressure and volume. Circulating levels of BNP and proBNP increase in proportion to the severity of heart failure. A rapid BNP point-of-care immunoassay may be performed, in which a venous blood sample is collected, placed on a strip, and inserted into a device that measures BNP. Results are completed in 10 to 15 min.
Galectin-3 protein levels are considered a prognostic tool in the assessment of diagnosed HF. Elevations in blood specimens greater than 17.8 ng/mL (as measured by enzyme immunoassay) are predictive of increased risk for progression of the disease.
Soluble ST-2 is another prognostic biomarker measured in blood samples, used to predict increased risk for progression of HF—elevations in patients identified with chronic heart failure predict elevated risk of disease progression ST-2 is an interleukin family receptor secreted by cardiac muscle in response to mechanical stress. Elevations in blood specimens greater than 35 ng/mL (as measured by enzyme immunoassay) are considered clinically significant.
CAD and MI are the most common causes of heart disease and most common causes of HF. Hypertension is another significant contributing factor in the development of HF. Other conditions that can contribute to the development or acceleration of HF include anemia, congenital heart defect, diabetes, kidney disease, and thyroid disease. Emphasis on preventive care, including the administration of aspirin, statins, beta blockers, ACE inhibitors, and the diuretic aldactone is becoming more important after CAD or MI have been diagnosed to offer protection to the damaged heart muscle.
Until 2017, patients with advanced HF had few alternatives to extend their lives if a heart transplant was not a timely option. The left ventricular assist device (LVAD), approved by the FDA, is a system comprised of an implanted pump and an external battery-powered pump controller designed to work in unison with the patient’s weakened left ventricle to provide additional blood flow.
Contraindications
Patients receiving nesiritide. Nesiritide (Natrecor) is a recombinant form of BNP that may be given therapeutically by IV to patients in acutely decompensated heart failure; with some assays, BNP levels may be transiently and significantly elevated at the time of administration and must be interpreted with caution. The testing laboratory should be consulted to verify whether test measurements are affected by nesiritide.
Factors that may alter the results of the study
BNP is secreted in response to increased hemodynamic load caused by physiological stimuli, as with ventricular stretch or endocrine stimuli from the aldosterone/renin system. Increasing BNP levels would indicate a worsening condition.
Decreasing BNP levels would indicate improvement.
Problems | Signs and Symptoms |
---|---|
Cardiac output (decreased—related to altered preload [increased/decreased], increased afterload, impaired cardiac contractility, cardiac muscle disease, altered cardiac conduction, side effects of medication) | Decreased peripheral pulses; decreased urinary output; cool, clammy skin; tachypnea; dyspnea; edema; altered level of consciousness; abnormal heart sounds; crackles in lungs; decreased activity tolerance; weight gain; edema; fatigue; hypoxia; hypotension |
Fluid volume (excess—related to decreased cardiac output; decreased renal perfusion) | Edema; shortness of breath; increased weight; ascites, rales, and rhonchi; diluted laboratory values; increased blood pressure; positive jugular venous distention (JVD); orthopnea; cough; restlessness; tachycardia; pulmonary congestion with x-ray; decreased urinary output; ascites; hypertension |
Gas exchange (inadequate—related to altered alveolar and capillary exchange secondary to fluid in the alveoli) | Decreased activity tolerance, increased shortness of breath with activity, weakness, orthopnea, cyanosis, cough, increased heart rate, weight gain, edema in the lower extremities, increased respiratory rate, use of respiratory accessory muscles |
Tissue perfusion (inadequate—related to compromised cardiac contractility, interrupted blood flow) | Hypotension, dizziness, cool extremities, capillary refill greater than 3 sec, weak pedal pulses, altered level of consciousness |
Teaching the Patient What to Expect
Treatment Considerations
Cardiac Output
Fluid Volume
Gas Exchange
Tissue Perfusion
Nutritional Considerations
Clinical Judgement
Followup Evaluation and Desired Outcomes