Dear Oras Yaseen
Glycogen is not present in serum because it cannot reach the blood as it is a large molecule that cannot pass through the blood vessels. It is a complex polysaccharide of glucose which serves as a form of energy storage. It is mainly synthesized in the liver and muscles. When glucose levels drop in the blood, glycogen is broken down to glucose. This glucose travels around the body through the bloodstream.
When glucose levels surge above a certain level, insulin is released into the blood, and this promotes the glucose in the organs like the liver and muscles to convert it to glycogen and store it. So, you cannot estimate glycogen in serum.
To estimate glycogen levels, you have to perform a biopsy, taking a piece of either muscle or liver tissue.
In case of muscle biopsy sample, collagen, blood, and other non-muscle fibre materials are removed from the sample under a microscope. The sample of muscle fibre (say 2–3 mg) are then weighed and 500µl of 1M HCL is added. After heating for 3 hours at 100°C to hydrolyze the glycogen to glycosyl units and cooling down to room temperature, the solution is then neutralized by adding 267ml Tris/KOH. Finally, 150µl is then analyzed for glucose using a calibrated specialized glycogen assay kit.
You may want to refer to the article attached below for more information.
Article State-of-the-Art Methods for Skeletal Muscle Glycogen Analys...
Please note that it’s hard to measure the total glycogen levels because the levels constantly change depending on the size, eating habits, fitness level and whether or not an individual has recently exercised.
The normal range of glycogen in muscles: 300 to 500 grams.
The normal range of glycogen in liver: 0 to 160 grams.
Best.
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