Uji Validitas Diagnostik Persentase Mikrosit (Micro%) untuk Deteksi Defisiensi Besi pada Dewasa Sehat

Devina Amanta Setiawan, Dr. dr.Tri Ratnaningsih, M.Kes, Sp.PK. Subsp.B.D.K.T.(K), Subsp.H.K.(K); dr. Riat El Khair, MSc., Sp.PK, Subsp.P.I.(K),QHIA, M.A.R.S

2025 | Tesis-Spesialis | S2 Ilmu Patologi Klinik

Latar belakang: Defisiensi besi (DB) merupakan masalah nutrisi global yang seringkali sulit didiagnosis sebelum berkembang menjadi anemia, terutama pada individu dengan tampakan klinis sehat. Parameter diagnostik standar seperti feritin serum tidak selalu tersedia dan dapat dipengaruhi oleh inflamasi, sementara parameter hematologi rutin seperti MCV dan MCH seringkali berubah pada tahap lanjut. Micro%, parameter baru yang menilai persentase eritrosit mikrositik, berpotensi menjadi alat deteksi dini DB yang murah dan cepat, namun validitas diagnostiknya belum banyak diteliti

Tujuan: mengetahui validitas diagnostik (AUC dan sensitivitas pada cut-off optimal) parameter Micro% untuk mendeteksi defisiensi besi.

Metode: Penelitian ini menggunakan desain observasional potong lintang dengan pendekatan uji diagnostik. Subjek penelitian adalah calon residen dan koas yang menjalani pemeriksaan kesehatan di Laboratorium Patologi Klinik FK-KMK UGM. Standar rujukan adalah kadar ferritin serum (SF) ? 30 µg/L. Subjek dengan kondisi perancu seperti kehamilan, menstruasi, riwayat terapi besi, transfusi, talasemia (HbA2 > 3,5% atau analisis genetik), atau inflamasi (CRP > 5mg/L) dieksklusi. Kurva ROC dan Indeks Youden (YI) digunakan untuk menentukan AUC, cut-off optimal, sensitivitas, dan spesifisitas.

Hasil: Dari 262 subjek yang memenuhi kriteria, 24 (9,16%) subjek mengalami DB. Analisis kurva ROC menghasilkan nilai AUC 0,845 (IK 95%: 0,740-0,949), yang menunjukkan validitas diagnostik yang baik. Cut-off optimal untuk Micro% didapatkan pada nilai 0,75% (YI tertinggi 0,585). Pada cut-off tersebut, Micro% memiliki sensitivitas 83,33%, spesifisitas 75,21%, Nilai Ramal Negatif (NRN) 90,56%, dan Nilai Ramal Positif (NRP) 61,27%.

Kesimpulan: Parameter Micro% memiliki validitas diagnostik yang baik (AUC 0,845) untuk mendeteksi defisiensi besi pada populasi dewasa sehat. Nilai cut-off optimal 0,75% memiliki akurasi, sensitivitas, dan spesifisitas yang baik.

Background: Iron deficiency (ID) is a global nutritional problem that is often difficult to diagnose before it develops into anemia, especially in seemingly healthy individuals. Standard diagnostic parameters such as serum ferritin are not always available and can be influenced by inflammation, while routine hematology parameters like MCV and MCH often only change in advanced stages. Micro%, a new parameter that assesses the percentage of microcytic erythrocytes, is a potential inexpensive and rapid tool for early detection of ID, but its diagnostic validity have not been extensively studied.

Objective: To determine the diagnostic validity (AUC and sensitivity of optimal cut-off) of the Micro% parameter for detecting iron deficiency.

Methods: This study used a cross-sectional observational design with a diagnostic test approach. The study subjects were resident candidates and undergraduate students undergoing health examinations at the Clinical Pathology Laboratory, Faculty of Medicine, Public Health, and Nursing (FK-KMK), UGM. The reference standard was serum ferritin ? 30 µg/L. Subjects with confounding conditions such as pregnancy, menstruation, history of iron therapy, transfusion, thalassemia (HbA2>3.5% or genetic analysis), or inflammation (CRP > 5mg/L) were excluded. ROC curves and the Youden Index were used to determine the AUC, optimal cut-off, sensitivity, and specificity.

Results: Of the 262 subjects who met the criteria, 24 (9.16%) had ID. ROC curve analysis produced an AUC value of 0.845 (95% CI: 0.740-0.949), which indicates good diagnostic performance. The optimal cut-off for Micro% was found to be 0.75% (highest Youden Index 0.585). At this cut-off, Micro% had a sensitivity of 83.33%, specificity of 75.21%, Negative Predictive Value (NPV) of 90.56%, and Positive Predictive Value (PPV) of 61.27%.

Conclusion: The Micro% parameter has good diagnostic validity (AUC 0.845) for detecting iron deficiency in a healthy adult population. The optimal cut-off value of 0.75% has good accuracy, sensitivity, and specificity.

Kata Kunci : uji diagnostik, status besi, defisiensi besi, feritin serum, Micro%