Impact of Blood Sample Timing on Cholesterol and Diabetes Tests

Q: Impact of Blood Sample Timing on Cholesterol and Diabetes Tests

● Lipid profile specimens： If whole blood is used, it can be stored at room temperature for 4 hours; however, clinics typically centrifuge whole blood to obtain serum/plasma, which can then be stored at room temperature (15-30°C) for 8 hours and at 2-8°C for 2-5 days. <br> <br>●

Blood test issues?

Hello, doctor.
I have high cholesterol and diabetes, and I have been regularly following up at a large hospital every three months.
However, as I am getting older, the long journey is becoming a bit too much for me.
I would like to switch to a small clinic near my home for my follow-ups.
However, I read in an online article that small clinics may wait for a certain number of patients to collect blood samples throughout the day before sending them to the laboratory for testing.
This means that unlike large hospitals, where samples are sent directly to the lab immediately after collection, the time difference in blood preservation could affect the accuracy of some tests.
This could lead to overestimation or underestimation of results, causing patients to mistakenly believe their condition is normal and delaying necessary treatment.
I would like to ask if the following tests would be affected by the time difference in blood preservation: 1.
Total cholesterol 2.
HDL 3.
LDL 4.
Fasting blood glucose 5.
Hemoglobin A1c.
Thank you for your help and clarification.

Legs not nimble grandma, 50~59 year old female. Ask Date: 2017/03/03

Dr. Chen Taicheng reply Family Medicine

● Lipid profile specimens: If whole blood is used, it can be stored at room temperature for 4 hours; however, clinics typically centrifuge whole blood to obtain serum/plasma, which can then be stored at room temperature (15-30°C) for 8 hours and at 2-8°C for 2-5 days.

● Fasting blood glucose specimens: These can remain stable at room temperature for 1 day and at 2-8°C for 7 days.

● Glycated hemoglobin specimens: These can be stored at room temperature for 24 hours, and plasma aliquots can be stored at 2-8°C for 48 hours.

● Generally, clinics send blood samples daily to contracted laboratories (usually the largest laboratories in the country).
These laboratories are well-equipped and staffed, and they are regularly evaluated by regulatory authorities, ensuring reliable testing quality.
Based on personal experience with patients presenting blood test reports from various clinics, there is typically no significant discrepancy when compared to results from hospitals.
If there are concerns about discrepancies in blood test results, it is advisable to have blood drawn at a clinic or hospital a day apart for comparison to understand the differences between testing facilities.
For chronic disease management, it is recommended to choose a healthcare facility closer to home to avoid the hassle of waiting and travel.
Wishing you good health, Dr.
Chen Tai-Cheng from Taoyuan Hospital, Family Medicine Department, cares for you.

Reply Date: 2017/03/03

More Info

When it comes to monitoring health conditions such as high cholesterol and diabetes, the timing and handling of blood samples can significantly impact the accuracy of test results. This is particularly relevant for individuals like yourself who are considering transitioning from a large hospital to a smaller clinic for regular check-ups. Let's break down how the timing of blood sample processing can affect various tests, including total cholesterol, HDL, LDL, fasting blood sugar, and HbA1c.

1. Total Cholesterol, HDL, and LDL: Cholesterol levels can be influenced by how long the blood sample is stored before analysis. Ideally, blood samples for lipid profiles should be processed as soon as possible after collection. If there is a delay in processing, particularly if the sample is not kept at the correct temperature, there can be changes in the lipid composition of the serum. For example, prolonged storage can lead to the breakdown of lipoproteins, potentially resulting in lower measured levels of HDL and LDL cholesterol. Therefore, if a clinic collects samples and waits to send them to a lab, this could lead to inaccuracies in your cholesterol readings.

2. Fasting Blood Sugar: Similar to cholesterol tests, fasting blood sugar levels are best measured immediately after blood collection. If there is a significant delay in processing the sample, glucose levels can decrease due to glycolysis, where glucose is metabolized by red blood cells. This could lead to an underestimation of your actual blood sugar levels, which is critical for diabetes management. For accurate fasting blood sugar results, it is essential that the sample is analyzed promptly.

3. HbA1c (Glycated Hemoglobin): HbA1c tests measure the average blood glucose levels over the past two to three months. Unlike glucose and cholesterol tests, HbA1c is less affected by the timing of sample processing. However, it is still important that the sample is handled correctly and analyzed within a certain timeframe to ensure accuracy. If the sample is stored improperly or for too long, it could potentially affect the results, but this is generally less of a concern compared to immediate glucose and lipid testing.

Given your concerns about the accuracy of tests at a smaller clinic, it is crucial to inquire about their protocols for blood sample handling and processing. Ask whether they send samples to a lab immediately after collection or if there is a delay. If there is a delay, it might be worth considering whether the potential inaccuracies in test results could impact your diabetes and cholesterol management.

In summary, the timing of blood sample processing is vital for accurate testing of total cholesterol, HDL, LDL, and fasting blood sugar. While HbA1c is somewhat more resilient to delays, proper handling is still important. If you decide to switch to a smaller clinic, ensure they have protocols in place to minimize delays in sample processing to maintain the accuracy of your health monitoring. Regular follow-ups and accurate testing are essential for managing conditions like high cholesterol and diabetes effectively.

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