Haptoglobin

 Q: Haptoglobin is an acute phase reactant?

A) True

B) False

Answer: A

Haptoglobin is an acute phase reactant and may be elevated in any inflammation. This bears an important clinical implication. It has a good negative specificity. A normal or elevated haptoglobin does not rule out hemolysis. In contrast, an undetectable haptoglobin level is almost consistent with hemolysis. 

As a rule of thumb, a haptoglobin level of 25 mg/dL can be considered a reliable cutoff point to rule out hemolysis. Ideally, haptoglobin level should be read with other indices of hemolysis such as LDH and indirect bilirubin.

#hematology

#laboratory science

References:

1. Marchand A, Galen RS, Van Lente F. The predictive value of serum haptoglobin in hemolytic disease. JAMA 1980; 243:1909. 

2. Stahl WM. Acute phase protein response to tissue injury. Crit Care Med 1987; 15:545.

3. Andersen CBF, Stødkilde K, Sæderup KL, Kuhlee A, Raunser S, Graversen JH, Moestrup SK. Haptoglobin. Antioxid Redox Signal. 2017 May 10;26(14):814-831. doi: 10.1089/ars.2016.6793. Epub 2016 Nov 8. PMID: 27650279. 

4. Shih AW, McFarlane A, Verhovsek M. Haptoglobin testing in hemolysis: measurement and interpretation. Am J Hematol. 2014 Apr;89(4):443-7. doi: 10.1002/ajh.23623. PMID: 24809098. 

5. Levy AP, Asleh R, Blum S, Levy NS, Miller-Lotan R, Kalet-Litman S, Anbinder Y, Lache O, Nakhoul FM, Asaf R, Farbstein D, Pollak M, Soloveichik YZ, Strauss M, Alshiek J, Livshits A, Schwartz A, Awad H, Jad K, Goldenstein H. Haptoglobin: basic and clinical aspects. Antioxid Redox Signal. 2010 Feb;12(2):293-304. doi: 10.1089/ars.2009.2793. PMID: 19659435.