Low myoglobin, with a result of 21 ng/ml, is not a diagnostic indicator of heart failure. Myoglobin is an oxygen-containing binding protein found mainly in the heart and skeletal muscles of the body. However, low myoglobin generally has no obvious clinical significance. Low myoglobin can occur in patients with wasting diseases such as hyperthyroidism and malignant tumors, as well as in some malnourished people. If the low myoglobin result is accompanied by abnormal wasting, you should go to the hospital in time. Heart failure, also known as heart failure, is a disease in which the blood supply to the heart is impaired for a variety of reasons, resulting in an inability of the blood supply to meet the basic requirements of the body’s tissues. When an individual is suspected of having heart failure, the diagnosis is usually confirmed by testing plasma brain natriuretic peptide and amino-terminal brain natriuretic peptide precursors, as well as troponin and electrocardiogram. Low myoglobin is generally not clinically significant and does not confirm heart failure. In the presence of abnormal laboratory results, specialist consultation is recommended to clarify the diagnosis.