Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (757 page)

Suggested Readings

Apple FS, Wu HB, Jaffe AS, et al. National Academy of Clinical Biochemistry and IFCC Committee for Standardization of Markers of Cardiac Damage Laboratory Medicine Practice Guidelines: Analytical issues for biomarkers of heart failure.
Circulation.
2007;226:e95–e98.

Steiner J, Guglin M. BNP or NTproBNP? A clinician’s perspective.
Int J Cardiol.
2008;129(1):5–14.

Tang WH, Francis GS, Morrow DA, et al. National Academy of Clinical Biochemistry Laboratory Medicine: National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines: clinical utilization of cardiac biomarker testing in heart failure.
Circulation.
2007;116(5): e99–e109.

BRONCHODILATORS

See Theophylline (1,3-Dimethylxanthine).

b-TRACE PROTEIN

   Definition

   β-Trace protein is also known as BTP or lipocalin-type prostaglandin D synthase. This test is currently not widely available in commercial laboratories. Research use only test. BTP, a low molecular weight glycoprotein freely filtered through the glomerular basement membrane and with minimal non-renal elimination, is an ideal marker for GFR. BTP has been shown to be a more sensitive marker of GFR than creatinine in patients with chronic kidney disease, in kidney transplant recipients, and in children.

   
Normal range:
0.40–0.74 mg/L.

   Use

   Alternative marker for GFR in children as well as in DM and various renal diseases.

   The early diagnosis of fistulas leaking CSF is an accurate marker of CSF leakage (CSF rhinorrhea).

   Limitations

   Patients with renal insufficiency and bacterial meningitis have increase serum and decreased CSF levels.

   There are no clear cut and accurate cutoff values available, which is a major determinant of diagnostic significance.

Suggested Reading

Pöge U, Gerhardt TM, Stoffel-Wagner B, et al. β-Trace protein is an alternative marker for GFR in renal transplantation patients.
Clin Chem.
2005;51:1531.

BUN-TO-CREATININE RATIO

   Definition and Use

   The BUN-to-creatinine ratio is used to differentiate prerenal and postrenal azotemia from renal azotemia. Because of considerable variability, it should be used only as a rough guide.

   
Normal range
(usual range for most people on normal diet: 12–16).