the Relationship Between Total Cholesterol and HDL/LDL Levels

The relationship between total cholesterol levels and high-density lipoprotein (HDL) cholesterol?

Hello, I would like to ask if there is an absolute additive relationship between total cholesterol and low-density lipoprotein (LDL) cholesterol.
My question arises from the following reference values: Last year’s check: Total cholesterol: 259 mg/dL, LDL cholesterol: 177 mg/dL, HDL cholesterol: 70 mg/dL, Triglycerides: 76 mg/dL.
This year: Total cholesterol: 231 mg/dL, LDL cholesterol: 177 mg/dL, HDL cholesterol: 70 mg/dL, Triglycerides: 47 mg/dL.
I am confused because the total cholesterol number is lower than the sum of the two values below it.
Please clarify this for me.
Thank you!

Tian Shi Hu Die, 40~49 year old female. Ask Date: 2019/05/14

Dr. Ye Qianyu reply Family Medicine

Hello! When triglycerides are less than 400, you can use the following formula to calculate low-density lipoprotein cholesterol: LDL-C = Total Cholesterol - HDL-C - TG/5.
Low-density lipoprotein cholesterol: LDL-C, High-density lipoprotein: HDL-C, Triglycerides: TG.
However, it is important to note that using this formula may also lead to an inaccurate estimation of LDL-C.
It is recommended that you obtain the original lab report and consult with a metabolic specialist for interpretation.
Since your LDL-C is already quite high, dietary and exercise management should be implemented, and regular follow-up in the outpatient clinic is advised.
Thank you for your question!

Reply Date: 2019/05/14

More Info

Understanding the relationship between total cholesterol, HDL (high-density lipoprotein), and LDL (low-density lipoprotein) levels can indeed be confusing, especially when the numbers do not seem to add up as expected. To clarify, total cholesterol is a measure of all the cholesterol in your blood, which includes HDL, LDL, and other lipid components. The relationship between these values is not always straightforward due to the way cholesterol is calculated and the presence of other factors.

The formula commonly used to estimate LDL cholesterol when triglyceride levels are below 400 mg/dL is:
LDL-C = Total Cholesterol - HDL-C - (Triglycerides / 5)
Using this formula, you can see how total cholesterol is derived from its components. However, it is important to note that this formula is an estimation and can sometimes lead to inaccuracies, particularly if triglyceride levels are elevated or if there are other underlying conditions affecting lipid metabolism.

In your case, let's analyze the numbers you provided:
- Last year:
- Total Cholesterol: 259 mg/dL
- LDL: 177 mg/dL
- HDL: 70 mg/dL
- Triglycerides: 76 mg/dL
- This year:
- Total Cholesterol: 231 mg/dL
- LDL: 177 mg/dL (remains the same)
- HDL: 70 mg/dL (remains the same)
- Triglycerides: 47 mg/dL
From your data, it appears that your total cholesterol has decreased, while your LDL and HDL levels have remained constant. This situation can arise because total cholesterol is not solely dependent on the sum of HDL and LDL. Other factors, such as the presence of other lipid particles (like VLDL - very low-density lipoprotein), can influence total cholesterol levels. Additionally, changes in triglyceride levels can also affect the total cholesterol calculation.

It's also worth noting that cholesterol levels can fluctuate due to various factors, including diet, exercise, weight changes, and metabolic health. For instance, if your triglycerides have decreased significantly, it may indicate improved metabolic health, which can positively affect your overall lipid profile.

Moreover, the relationship between body fat and cholesterol levels is complex. While higher body fat percentages can correlate with higher cholesterol levels, this is not always the case. Some individuals with higher body fat may have normal or even low cholesterol levels, as seen in your situation. This discrepancy can be attributed to genetic factors, lifestyle choices, and overall metabolic health.

In conclusion, while there is a relationship between total cholesterol, HDL, and LDL, it is not a simple additive one. The presence of other lipid components and individual metabolic factors can lead to variations in these values. If you have concerns about your cholesterol levels or overall cardiovascular health, it is advisable to consult with a healthcare professional who can provide personalized guidance based on your complete health profile. Regular monitoring and lifestyle modifications, such as a balanced diet and regular exercise, can significantly impact your lipid levels and overall health.

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