Sorted By Test Name - Mayo Medical Laboratories

PBNP
84291
characterized by QRS widening leading to ventricular tachycardia and asystole. In some patients, toxicity
may manifest at lower concentrations.
Useful For: Monitoring serum concentration during therapy Evaluating potential toxicity The test may
also be useful to evaluate patient compliance
Interpretation: Most individuals display optimal response to nortriptyline with serum levels of 70 to
170 ng/mL. Risk of toxicity is increased with nortriptyline levels > or =300 ng/mL. Some individuals may
respond well outside of this range, or may display toxicity within the therapeutic range; thus,
interpretation should include clinical evaluation. Therapeutic ranges are based on specimens drawn at
trough (ie, immediately before the next dose).
Reference Values:
Therapeutic concentration: 70-170 ng/mL
Toxic concentration: > or =300 ng/mL
Note: Therapeutic ranges are for specimens drawn at trough (ie, immediately before next scheduled
dose). Levels may be elevated in non-trough specimens.
Clinical References: 1. Wille SM, Cooreman SG, Neels HM, Lambert WE: Relevant issues in the
monitoring and the toxicology of antidepressants. Crit Rev Clin Lab Sci 2008;45(1):25-89 2. Thanacoody
HK, Thomas SH: Antidepressant poisoning. Clin Med 2003;3(2):114-118 3. Baumann P, Hiemke C,
Ulrich S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in
psychiatry. Pharmacopsychiatry 2004;37(6):243-265
NT-Pro B-Type Natriuretic Peptide (BNP), Serum
Clinical Information: B-type natriuretic peptide (brain natriuretic peptide [BNP]) is a small, ringed
peptide secreted by the heart to regulate blood pressure and fluid balance.(1) This peptide is stored in and
secreted predominantly from membrane granules in the heart ventricles in a pro form (Pro BNP). Once
released from the heart in response to ventricle volume expansion and/or pressure overload, the
N-terminal (NT) piece of 76 amino acids (NT-Pro BNP) is rapidly cleaved by the enzymes corin and/or
furin to release the active 32 amino acid peptide (BNP).(2) Both BNP and NT-Pro BNP are markers of
atrial and ventricular distension due to increased intracardiac pressure. The New York Heart Association
(NYHA) developed a 4-stage functional classification system for congestive heart failure (CHF) based on
the severity of the symptoms. Studies have demonstrated that the measured concentrations of circulating
BNP and/or NT-Pro BNP increase with the severity of CHF based on the NYHA classification.(4,5,6)
Useful For: An aid in the diagnosis of congestive heart failure
Interpretation: NT-pro BNP values 450 pg/mL are consistent with CHF in adults
under age 50; while in adults aged 50 years and older a diagnostic cut-off of 900 pg/mL has been
suggested in the absence of renal failure. NT-Pro BNP levels are loosely correlated with NYHA
functional class (see Table). Interpretive Levels for CHF Functional Class 5th to 95th Percentile Median I
31-1,110 pg/mL 377 pg/mL II 55-4,975 pg/mL 1,223 pg/mL III 77-26,916 pg/mL 3,130 pg/mL IV * * *In
a Mayo Clinic study of 75 patients with CHF, only 4 were characterized as Class IV. Accordingly, range
and median are not provided.
Reference Values:
Males
< or =45 years: 10-51 pg/mL
46 years: 10-53 pg/mL
47 years: 10-55 pg/mL
48 years: 10-56 pg/mL
49 years: 10-58 pg/mL
50 years: 10-59 pg/mL
51 years: 10-61 pg/mL
52 years: 10-62 pg/mL
53 years: 10-64 pg/mL
Current as of January 4, 2013 7:15 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 1321