AbstrakThalasemia merupakan kelainan hemolitik yang ditandai dengan penghancuran sel darah merah secara berlebihan. Penyakit ini diwariskan secara autosomal resesif dari orangtua yang berakibat pada kelainan sintesis rantai globin. Pasien thalasemia menjalani pengobatan dengan transfusi darah setiap bulan selama hidupnya. Pengobatan tersebut menimbulkan efek samping yang signifikan terhadap tubuh pasien. Transfusi darah yang terus menerus dapat menyebabkan penimbunan zat besi sehingga kadar feritin dalam tubuh meningkat. Selain itu, pasien thalasemia berisiko mengalami gangguan kelenjar endokrin dan anemia. Kondisi tersebut menyebabkan anak menjadi tidak mempunyai nafsu makan sehingga asupan gizi bekurang. Penelitian ini dilaksanakan di RSUD Al-Ihsan Januari–Desember 2022. Tujuan penelitian ini adalah mengetahui pengaruh kadar feritin darah terhadap status gizi pasien thalasemia β mayor anak. Metode penelitian ini, yaitu observasional analitik melalui pendekatan cross sectional. Subjek penelitian ini berjumlah 58 orang. Alat yang digunakan pada penelitian adalah grafik pertumbuhan berdasarkan The WHO Reference 2007. Hasil studi menunjukkan p=0,004 (p<0.05) dengan nilai r sebesar 0,536 yang berarti terdapat pengaruh kadar feritin terhadap status gizi pasien thalasemia β mayor anak di RSUD Al-Ihsan Kabupaten Bandung tahun 2022. Simpulan, kadar feritin darah berpengaruh terhadap status gizi pasien thalasemia β mayor anak. Effect of Blood Ferritin Levels on Nutritional Status of Pediatric Patients with Thalassemia β MajorAbstractThalassemia is a hemolytic disorder characterized by excessive destruction of red blood cells. The disease is inherited autosomal recessive from the elderly resulting in abnormalities in the synthesis of globin chains. The thalassemia patient undergoes treatment with blood transfusions every month during his lifetime. Such treatment causes significant side effects to the patient's body. Continuous blood transfusions can cause iron accumulation so that ferritin levels in the body increase. In addition, thalassemia patients are at risk of endocrine gland disorders and anemia. This condition causes the child to have no appetite, so the nutritional intake is frozen. This research was conducted at Al-Ihsan Hospital January-December 2022. This study aimed to determine the effect of ferritin levels on the nutritional status of children with β thalassemia major. This research method is analytically observational through a cross-sectional approach. The subjects of this study amounted to 58 people. The tool used in this study was a growth chart based on the 2007 WHO Reference. The analysis results showed p= 0.004 (p-value<0.05) and r value of 0.536, which means that there is an effect of ferritin levels on nutritional status of pediatric patients with thalassemia β major at Al-Ihsan Hospital, Bandung Regency in 2022. This study concludes that ferritin levels affect the nutritional status of children with β thalassemia major.