['Remnant lipoproteins are atherogenic and are accumulated in patients with type III hyperlipidemia (HL). Although type III HL is diagnosed by phenotyping apolipoprotein (apo) E, this procedure is time-consuming and inconvenient for routine clinical use. Clinical indices for screening type III HL in untreated HL patients have been proposed; however, in clinical settings, HL patients are promptly treated with lipid-lowering agents without diagnosing the underlying cause. We investigated whether existing clinical indices for screening type III HL as well as the apo B-48/triglyceride (TG) ratio, which was suggested to be related to the accumulation of small chylomicron (CM) remnants, are useful after the initiation of lipid-lowering therapies.', 'In 25 normolipidemic subjects and 191 treated HL patients (type I, n =6; IIa, 62; IIb, 66; III, 12; IV, 22; and V, 23) from Osaka University Hospital and related hospitals, fasting low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), TG, and apolipoproteins were measured and clinical indices were evaluated statistically.', 'Apo B-48 levels were significantly higher in patients with type I, III, and V HL, and TG levels were significantly higher in patients with type I and V HL. The apo B-48/TG ratio was significantly higher only in patients with type III HL compared with other types of HL (p<0.001), and was statistically significant among the other clinical indices (AUC-ROC value, 0.895; cut-off value, 0.110).'] Is apolipoprotein B-48 to triglyceride ratio a novel and useful marker for detection of type III hyperlipidemia after antihyperlipidemic intervention?