Myoglobin- What it is? Functions, Tests and Results

MYOGLOBIN

Introduction

Myoglobin is a protein typically found in vertebrates’ striated muscles. The MB gene produces myoglobin in humans. It contains one oxygen binding site and encodes a single polypeptide chain.

In general, a globin and heme molecule combine to form the dark red protein known as myoglobin. The major purpose of myoglobin is to provide the skeletal and cardiac muscles with oxygen.

A tiny proportion of myoglobin proteins are eliminated in the urine, just like all other low-molecular-weight proteins. Less than 10 g/L of myoglobin is considered to be the normal concentration in urine. Myoglobin has a normal serum concentration of less than 100 g/L.

Are myoglobin and haemoglobin the same?

Myoglobin and haemoglobin are both globulin-chained oxygen-binding proteins. Each one is a globular protein with a heme group that binds oxygen. Myoglobin and haemoglobin differ primarily in their structure and mode of action.

Function of myoglobin

Oxygen diffusion is facilitated by myoglobin. At the start of muscle contraction, myoglobin desaturates, increasing the gradient of oxygen transport from the capillaries to the cytoplasm. It has also been demonstrated that myoglobin possesses enzymatic activities.

The oxygen-binding molecule found in muscles is called myoglobin. Although it shares a structure with haemoglobin, this does not aid in oxygen delivery. Its primary purpose is to store oxygen in muscle tissue so that it can be used when there is an oxygen deficit.

Causes of high myoglobin

The following are some of the causes of high myoglobin. Myoglobin levels that are greater in your blood or urine might be caused by a number of circumstances, including:

Rhabdomyolysis

High myoglobin level indicates the levels of myoglobin in your blood are due to rhabdomyolysis (a condition involving a rapid breakdown of muscle tissue).

A severe injury can cause rhabdomyolysis to your muscles from several different sources, like trauma and crushing injuries, such as car or bike accidents. Higher myoglobin levels may indicate muscle injury.

Heart attack

Myoglobin levels that suddenly rise may indicate a cardiac attack that damages the heart muscle.

Malignant hyperthermia

Most frequently, malignant hyperthermia is due to a strong reaction to anaesthetics and muscle relaxants. It may also occur if your body experiences extreme heat stress. Muscle rigidity and spasms are some of the signs of malignant hyperthermia.

Symptoms of high myoglobin

The following are some of the symptoms of myoglobin:

Muscle pain

Muscle pain is one of the early indicators of high myoglobin. Sometimes, muscle pain may be accompanied by severe headaches and body fatigue.

Dark-coloured urine

Rhabdomyolysis can also result from muscular damage brought on by strenuous activity. As a result, urine is either in pink or dark colour.

When to take a test?

If you exhibit signs of significant muscle damage, such as from incidents that result in muscle trauma or muscular dystrophy, your doctor may prescribe a myoglobin blood test. Some of the myoglobin tests are:

Serum-myoglobin (myoglobin blood test)

A serum myoglobin test can determine the amount of myoglobin in your blood. If your doctor believes you are suffering a heart attack, they may request this test. Heart attacks are frequently easy to recognise based on symptoms and family history. But there are situations when a heart attack is not immediately apparent.

Myoglobin urine test

Excessive myoglobin levels can harm the kidneys. A doctor recommends this test when they suspect heart or skeletal muscle damage.

Comprehensive metabolic panel (CMP) test

A comprehensive metabolic panel (CMP) test can be used to assess blood sugar (glucose) levels, electrolyte and fluid balance, and the condition of your kidneys and liver.

Tests to detect calcium, phosphate and albumin

A serum calcium blood test is recommended to measure the total amount of calcium in your blood. These tests can also help to detect albumin and phosphate. The most active form of calcium is ionised calcium, commonly referred to as free calcium.

Creatine phosphokinase (CPK) test

The heart, brain or muscles are most frequently injured or stressed when the total CPK level is exceptionally high. This can be figured out by a test called the Creatine phosphokinase (CPK) test.

Electrocardiogram

This examination tracks the electrical impulses coming from the heart.

Imaging tests

Your heart can undergo a number of scans to look for damage, clotting and other issues that could impair its capacity to pump blood.

Test results

Higher myoglobin levels

Higher myoglobin levels in the urine indicate the damage caused in the skeletal muscles resulting in the rapid breakdown of muscles.

A higher level of myoglobin leads to kidney damage since myoglobin is toxic to your kidneys.

Lower myoglobin levels

Normal myoglobin blood levels begin at zero. Having low myoglobin levels has no medical significance. Similarly, normal urine has no or tiny amounts of myoglobin.

Treatment for high myoglobin

The following are some of the treatments given for high myoglobin.

Intermittent dialysis does not help remove myoglobin and for preventing kidney damage. It should be considered in patients with rhabdomyolysis who develop acute renal failure. Indications include a hypercatabolic state, volume overload, acidosis and hyperkalaemia.

Prevention of high myoglobin

High levels of myoglobin can be prevented in the following ways:

Before exercise, hydrate yourself

Drink 15 – 20 ounces of water 2 to 3 hours before exercise. Drinking 3 litres of fluid a day is mandatory whether or not you are exercising. Don’t wait until you’re thirsty to drink. Thirst is a late sign of dehydration.

Carry a water bottle

Always make sure to stay hydrated throughout the day. Carrying a water bottle helps hydrating oneself. Dehydration increases the chance of formation of high myoglobin content in the body.

When to see a doctor?

Healthcare providers may recommend a myoglobin blood test if you’re experiencing symptoms of severe muscle damage, such as from accidents resulting in muscle trauma or muscular dystrophy.

Conclusion

Seeing an abnormal test result can be stressful and doesn’t necessarily mean you have a medical condition.

Your healthcare provider will give intimation when you need to undergo further tests to determine the cause of the elevated myoglobin level. Don’t be scared to ask questions to your healthcare provider. They’re there to help you.

FAQ

Is myoglobin found in blood?

Myoglobin is present in the striated muscles, and haemoglobin is found in your bloodstream. Myoglobin only enters your bloodstream if you experience muscle damage.

When can I get the results of my myoglobin test?

Since healthcare providers usually order myoglobin tests for extreme or emergencies, such as extensive muscle trauma or heart attacks, they’ll likely have the test results within minutes or hours.

Does excess myoglobin excretion lead to heart attack?

Myoglobin excretion does not lead to a heart attack. However, high excretion of myoglobin may damage the kidney.

How to prevent muscle breakdown?

The following are the ways to prevent muscle breakdown.
1 · Eat protein
2· Resistance train
3· Increase Your Omega-3s
4· Check your vitamin D levels
5· Walk

What is the average myoglobin level?

The average myoglobin range is 25 to 72 ng/mL.

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