Elevated estradiol in a prepubertal female: within-laboratory systematic and practical interference screening

Area of Science:

• Clinical Chemistry
• Analytical Biochemistry
• Laboratory Medicine

Background:

• Analytical errors in immunoassays can stem from interfering substances.
• Such interferences may lead to unnecessary medical investigations and patient anxiety.
• Estradiol measurement is particularly susceptible to interference on immunoassay platforms.

Purpose of the Study:

• To systematically screen for estradiol interference using a practical algorithm.
• To compare the performance of different immunoassay platforms and LC-MS/MS for estradiol measurement.
• To evaluate the impact of specific interference mitigation techniques.

Main Methods:

• Method comparison involving three immunoassay platforms and one LC-MS/MS.
• Serial dilution tests to assess linearity.
• Polyethylene glycol (PEG) precipitation to identify interference.
• Heterophile antibody blocking tube assay.

Main Results:

• Deviation from linearity observed during serial dilution tests.
• Polyethylene glycol (PEG) precipitation yielded a recovery rate of 63%.
• Significant discrepancies in patient estradiol values across different immunoassay platforms (e.g., Siemens: 389.02 pmol/L vs. Abbott: <36.7 pmol/L).
• LC-MS/MS provided a substantially lower and potentially more accurate estradiol value (3.33 pmol/L).

Conclusions:

• Immunoassays are prone to interferences, potentially causing overestimated estradiol results due to cross-reactivity.
• Liquid chromatography-mass spectrometry (LC-MS/MS) demonstrates greater suitability for accurate estradiol quantification.
• LC-MS/MS can aid in preventing misdiagnosis and inappropriate treatments, particularly in pediatric patients.