Routine laboratory test results are usually normal in patients with cholinesterase inhibitor toxicity. However, a few notable exceptions may confound the diagnosis. Examples are listed in the table below. (Schenker, Louie et al. 1998; Tareg et al. 2001; Wiener and Hoffman 2004)
Laboratory Test |
Results That May Occur in Cholinesterase Inhibitor Toxicity |
Presumed Cause |
EKG
Note: In a series of 105 cases, Hayes et al. found that --- with the exception of rate changes --- EKG abnormalities occurred only 5% of the time. (Hayes, van der Westhuizen et al. 1978) |
- Tachycardia or bradycardia (Leikin, Thomas et al. 2002)
- A-V block (Suzuki, Kohno et al. 1997)
- Prolonged Q-T (Clark 2002)
- Peaked T-waves (Hayes, van der Westhuizen et al. 1978)
- Torsades de pointes (Leikin, Thomas et al. 2002)
|
|
Ketoacidosis |
Present (Schenker, Louie et al. 1998) |
n/a |
Serum amylase |
Elevated (Tareg et al. 2001; Wiener and Hoffman 2004) |
Injury to pancreas from parasympathetic overstimulation and hypersecretion (Tareg et al. 2001) |
Serum creatine kinase (CK) |
Elevated (Okumura, Takasu et al. 1996; Wiener and Hoffman 2004) |
Fasciculations, seizures |
Serum glucose |
Elevated (Hayes, Wise et al. 1980; Schenker, Louie et al. 1998; Tareg et al. 2001) |
Nicotinic effect on the adrenal medulla with catecholamine release (Tareg et al. 2001) |
Serum lipids and triglycerides |
Decreased (Wiener and Hoffman 2004) |
n/a |
Serum potassium |
Decreased (Suzuki, Kohno et al. 1997; Tareg et al. 2001; Wiener and Hoffman 2004)
Increased |
Nicotinic effect on the adrenal medulla with catecholamine release (Tareg et al. 2001)
Effect of muscular activity during seizures |
Urine glucose |
Elevated (Hayes, Wise et al. 1980; Schenker, Louie et al. 1998; Tareg et al. 2001) |
Nicotinic effect on the adrenal medulla with catecholamine release (Tareg et al. 2001) |
Urine proteins |
Elevated (Hayes, Wise et al. 1980; Schenker, Louie et al. 1998; Tareg et al. 2001) |
n/a (Tareg et al. 2001) |
White blood cell count |
Elevated with a left shift (Hayes, Wise et al. 1980; Okumura, Takasu et al. 1996; Schenker, Louie et al. 1998; Tareg et al. 2001) |
Nicotinic effect on the adrenal medulla with catecholamine release (Tareg et al. 2001) |
n/a = not addressed in the reference. |