Friday, September 15, 2023

Blood tests in clozapine-induced myocarditis

Q: 32 years old male patient with history of severe schizophrenia, who was discharged from the hospital a month ago, now presented at Emergency Department with complaints of shortness of breath and has acute congestive heart failure. Clozapine-induced myocarditis was diagnosed. Combination of which two tests can give 100 percent sensitivity in detecting clozapine-induced myocarditis? (select one)

A) C-reactive protein (CRP) & troponin 
B) Eosinophilia & B-Type Natriuretic Peptide (BNP)
C) BNP & Troponin
D) Potassium and Creatinine


Answer: A

Besides classic symptoms of congestive heart failure (CHF), i.e., shortness of breath or leg edema - a combination of elevations of two blood tests: CRP and Troponins, provide almost 100 percent sensitivity in detecting clozapine-induced myocarditis (choice A). 

Eosinophilia is also common but is less reliable and often a delayed finding (choice B).

BNP is universally common in CHF and does not provide diagnostic accuracy for a specific cause (Choices B and C).

In the late stage, Hyperkalemia and renal insufficiency may ensue with decreased cardiac pump function and cardio-renal syndrome. This is also universal in all late CHF patients (choice D).


#cardiology
#laboratory-medicine


Reference:

Ronaldson KJ, Fitzgerald PB, Taylor AJ, et al. A new monitoring protocol for clozapine-induced myocarditis based on an analysis of 75 cases and 94 controls. Aust N Z J Psychiatry 2011; 45:458.

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