Tekrarlayan serum PSA ölçümlerindeki farklılıkların referans değişim değeri ile karşılaştırılması

Amaç: Prostat kanseri, erkeklerde en sık görülen kanserlerden biridir. Prostat spesifik antijen (PSA), prostat kanseri tanısında ve izleminde sıklıkla kullanılan biyokimyasal bir parametredir. Prostat spesifik antijenin birey içi değişkenliğinin yüksek olmasından dolayı, bir bireyden art arda yapılan iki ölçüm arasındaki değişimin anlamlılığını değerlendirmek önem arz etmektedir. Çalışmamızda, tekrarlayan serum PSA ölçümlerindeki farklılığın Referans Değişim Değerini (RCV) aşıp aşmadığı araştırılarak, gereksiz PSA istemlerinin önüne geçmek amaçlanmıştır. Gereç ve yöntem: Toplam 4154 hastaya ait PSA istemleri retrospektif olarak analiz edildi. Farklı zaman aralıklarında sonucu bulunan ve ilk PSA sonucu 2-10 ng/mL arasında değişen 268 kişi seçildi. Total PSA için analitik değişkenlik % 5,1 olarak bulundu. RCV %52 olarak hesaplandı. Bulgular: Çalışmaya aldığımız 268 kişinin 126 (%47)’sının serum PSA seviyelerinde düşme olurken 142 (%53)’sinin serum PSA seviyelerinde artış görüldü. PSA düzeyleri ikinci ölçümde artmış saptanan 142 hastadan 26’sında %52’lik RCV değerini aşacak düzeyde yükselme gözlendi. Çalışmamızda tekrarlayan PSA istemi olan hastaların sadece %9,7’sinde RCV düzeyini aşan bir oransal yükselme olduğunu saptadık. Sonuç: PSA değerlerindeki yükselme değerlendirilirken RCV değerini aşıp aşmadığı dikkate alınarak yorum yapılmalıdır. Çalışmamızda PSA’daki oransal yükselmelerin çoğu RCV’yi aşmadığından, bu yükselmelerin anlamı tartışmalıdır.

Anahtar Kelimeler:

Prostat spesifik antijen, referans değişim değeri, biyolojik değişkenlik

Comparison Of Differences In Recurrent Serum PSA Measurements With Reference Change Value

Objective: Prostate cancer is one of the most common cancers in men. The prostate-specific antigen is a biochemical parameter that is often used to diagnose and monitor prostate cancer. Since the intra-individual variability of the prostate-specific antigen is high, it is important to assess the significance of the change between two consequtive measurements from one individual. In our study, it was aimed to avoid unnecessary PSA requests by investigating whether the difference in recurrent serum PSA measurements exceeded Reference Change Value (RCV).Material and method: PSA requests for a total of 4154 patients were retrospectively analyzed. A total of 268 individuals having repeated test results with first PSA result ranging from 2-10 ng/mL were selected. Analytical variability for total PSA was found as 5.1% and RCV was calculated as 52%.Results: While there was a decrease in serum PSA levels in 126 (47%) of the 268 patients who were included in the study, there was an increase in 142 (53%). Among 142 patients whose PSA levels had increased in the second measurement, 26 had increases exceeding the RCV. In our study, we found that only 9.7% of patients with recurrent PSA requests had an increment above RCV.Conclusion: When the increase in PSA values is evaluated, it should be checked if it exceeds the RCV value and interpreted accordingly. The significance of these elevations is controversial since most of the increment percent in PSA observed in our study did not exceed RCV.

Keywords:

Prostate specific antigen, reference change value, biological variation,

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