What does low myoglobin mean?

Myoglobin is a very important protein in the human body. The oxygen we usually inhale is stored and distributed in this place. Maintaining the myoglobin content at a normal level is the guarantee of our body's normal functioning. An increase or decrease in the myoglobin content indicates that there is some problem in the body. High myoglobin may be caused by hypothyroidism, muscular dystrophy, muscular atrophy, etc. So, what does low myoglobin mean?

Low myoglobin is normal, but high myoglobin may indicate a problem. Myoglobin (Mb) is a protein that stores and distributes oxygen in mammalian cells (mainly muscle cells). It is composed of a polypeptide chain and a cofactor heme, with a relative molecular mass of 16,700 and contains 153 amino acid residues. Apomyoglobin without hemoglobin is called globin. It has obvious homology with the subunits of hemoglobin (a-globin chain and P-globin chain) in amino acid sequence, and their conformations and functions are also extremely similar.

Clinical significance of myoglobin:

Determination of serum myoglobin Myoglobin can be used as the most sensitive indicator for the early diagnosis of acute myocardial infarction (AMI). However, its specificity is poor, and diseases such as skeletal muscle injury, trauma, and renal failure can all lead to its increase. Although Myo positivity cannot confirm AMI, it is an important indicator for early exclusion of AMI diagnosis. If Myo is negative, myocardial infarction is basically excluded. It can also be used to diagnose reinfarction. Combined with clinical findings, if Myo rises again, it should be considered as reinfarction or extended infarction.

Increased: seen in the early stages of acute myocardial infarction, acute muscle injury, muscular dystrophy, muscular atrophy, polymyositis, acute or chronic renal failure, severe congestive heart failure and long-term shock, etc. It may increase 1.5 hours after myocardial infarction, but return to normal within 1 to 2 days.

(1) Increased blood levels: hypothyroidism, hyperaldosteronism, renal insufficiency, malignant hyperthermia, and after strenuous exercise, etc.

(2) Increased in urine: porphyria, hemoglobinuria, hematuria, etc.

(3) Elevated myoglobin levels in both blood and urine: seen in acute myocardial infarction, angina pectoris, cardiogenic shock, cardiomyopathy, muscle diseases (progressive muscular dystrophy, polymyositis, myasthenia gravis), etc.

Reference value

Male: 20~80μg/L;

Female: 10~70μg/L;

Diagnostic limit: >100μg/L.

Serum Mb levels vary with age, gender and race, and are higher in blacks than in whites.