Lab Med Online.  2020 Apr;10(2):132-136. 10.3343/lmo.2020.10.2.132.

Evaluation of Intact Parathyroid Hormone Levels in Plasma Samples: A Comparative Study Using Serum Samples

• Kim DH
• Kim SH
• Choi HW
• Kim H
• Oh Ac
• Hong YJ
• Lee JK

• KMID: 2512243
• DOI: http://doi.org/10.3343/lmo.2020.10.2.132

Abstract

Background
Intraoperative measurement of intact parathyroid hormone (iPTH) levels is crucial for confirming complete removal of hyperfunctioning parathyroid glands during parathyroidectomy and for detecting parathyroid gland damage during thyroidectomy. The use of plasma samples can shorten the turnaround time (TAT) for iPTH. The present study explored the effectiveness of using plasma samples for iPTH quantitation by comparison with the corresponding serum samples. We also evaluated the analytical performance of iPTH.
Methods
The TAT of plasma and serum samples analyzed in March 2019 was compared. In addition, comparative evaluation of the iPTH levels in 100 paired plasma and serum samples were performed. Analytical performances including within-run and within-laboratory precision, and linearity were evaluated in plasma samples using the ADVIA Centaur iPTH assay (Siemens Healthineers, Germany). The reference range was verified with plasma samples collected from 20 healthy adults.
Results
Plasma iPTH tests showed shorter TAT values (P<0.001) and higher iPTH levels (P<0.001) than serum. Correlation analysis between plasma and serum iPTH levels showed a strong positive correlation (r=0.925). The within-run and within-laboratory precision values were within the manufacturer's recommendation. iPTH showed linearity from 5.1 to 1,670.0 pg/mL (R2=0.999). The plasma iPTH levels from 20 healthy adults were within the reference range, thus validating our method.
Conclusions
The plasma iPTH levels were higher than the serum levels, with a strong positive correlation. The TAT of plasma samples was considerably shorter than that of serum. iPTH quantitation from plasma samples is preferable when rapid results are required.

Keyword

Intact parathyroid hormone; Comparison; Plasma; Serum

Figure

• 

  Fig. 1 Linearity of the Siemens ADVIA Centaur XP immunoassay system for iPTH quantification. Good linearity is observed in the range from 5.1 to 1,670.0 pg/mL (R2 =0.999). Abbreviation: iPTH, intact parathyroid hormone.

• 

  Fig. 2 Box plot of plasma and serum iPTH measurements. Plasma sam-ples show significantly higher iPTH levels compared with serum samples (median value of 41.1 vs 35.1 pg/mL, P <0.001). Abbreviation: iPTH, intact parathyroid hormone.

• 

  Fig. 3 Scatter plot of plasma and serum iPTH measurements. Plasma and serum iPTH levels show a strong positive correlation (r=0.925). Abbreviation: iPTH, intact parathyroid hormone.

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