Cholestech L·D·X® FAQ's

We are here to provide you with information to help you understand and run your Cholestech L·D·X® System.  We'll start with some of the questions most frequently asked by customers.  If you don't see your question here, e-mail us and let us know your question, or call +44 (0)1793 840073.

 

Q1 What are the "normal ranges" for Total Cholesterol, HDL Cholesterol & Triglycerides?
Q2 What is the measuring range of the Cholestech L·D·X System?
Q3 How closely should the Cholestech L·D·X System results agree with my current lab results?
Q4 Do I need to calibrate my Cholestech L·D·X System?
Q5 Do my patients need to be fasting for testing on the Cholestech L·D·X System?
Q6 Why am I getting N/A for my HDL Cholesterol result?
Q7 Why am I getting N/A for my LDL result?
Q8 Why do I have to run the Optics Cassette and Controls?
Q9 How often do I have to run Quality controls?
Q10 How long can I use my cassettes? How long can I keep my cassettes at room temperature?
Q11 Can I use capillary tubes which are not Cholestech capillary tubes?
Q12 An error message "Mag Read Error" appears on the L·D·X. What does this mean?
Q13 An error message "Tray Timeout" appears on the L·D·X.  What do I do?
Q14 An error message "Reaction did not occur" appears on the L·D·X.  What do I do?
Q15 An error message "WARN 1" is displayed on the L·D·X.  What should I do?
Q16 An error message "WARN 2" is displayed on the L·D·X. What should I do?
Q17 An error message "WARN 3" is displayed on the L·D·X.  What should I do?
Q18 An error message "Optics Test Fail" is displayed on the L·D·X. What should I do?
Q19 An error message "Bad Checksum" is displayed on the L·D·X. What should I do?
Q20 I have an LDX with version 1.4 ROM pack? Can I use the new Cholestech LDX Printer?
Q21 Will my Seiko printer work with the new version 2.02 ROM pack?
Q22 What is ALT?
Q23 Why measure ALT?
Q24 What are the usual expected ranges for the Cholestech LDX ALT controls?
Q25 What is the expected value for ALT in normals?
Q26 What is the normal measuring range for ALT on the LDX?
Q27 How much higher than normal can ALT be raised?
Q28 What factors cause raised ALT?
Q29 On completion of the LDX ALT test the result showed up as N/A on the screen - why?
Q30 I have two MiniPet pipettes, a grey(50ul) and a brown (35ul) - which one should I use for what purpose?
Q31 I only have a grey (50ul) MiniPet Pipette - what should I do?

  • Question: What are the "normal ranges" for Total Cholesterol, HDL Cholesterol and Triglycerides?
  • Answer:
    • Total Cholesterol:
      • Desirable: Less than 5.2 mM/L
      • Borderline:5.2 - 6.2 mM/L
      • High: Greater than 6.22 mM/L
    • HDL Cholesterol:
      • A desirable HDL Cholesterol level is greater than 1.1 mM/L)
    • Triglycerides: (fasting):
      • Normal: Less than 2.26 mM/L
      • Borderline: high 2.26 - 4.52 mM/L)
      • High: 4.52 - 11.29 mM/L
      • Very high: greater than 11.3 mM/L
  • Question: What is the measuring range of the Cholestech L·D·X® System?
  • Answer: The measuring range for each analyte is as follows:
    • Total Cholesterol : 2.58 - 12.92 mM/L
    • HDL Cholesterol : 0.39 - 2.59 mM/L
    • Triglycerides : 0.51 - 7.34 mM/L
    • Glucose : 2.78 - 27.75 mM/L
Results outside these ranges will be reported as less than (<) the lower limit or greater than (>) the upper limit.  If repeat testing gives the same < or > result the sample should be sent to a clinical lab for testing.
  • Question: How closely should the Cholestech L·D·X® System results agree with my current lab results?
  • Answer: The Cholestech L·D·X® System gives you the same level of accuracy and precision that you would get from a clinical lab. The MDA report (MDA/95/23) confirms that the results from L·D·X® capillary samples for total cholesterol compared with the venous samples on the Kodak 700 laboratory analyser gives a minimal -4% bias; the report confirms an imprecision of around 5% for total cholesterol, 5 - 10% for HDL and 6 - 10% for triglycerides.
It is not always recognised that many other measurements demonstrate significant differences between capillary and venous samples, such as that of blood glucose, where it is usually a 10 - 15% difference.
Our experience is that the L·D·X® instrument, in the hands of trained non-laboratory staff, does generate reliable results, due to the instrument design and the quality control mechanisms we have added.
  • Question: Do I need to calibrate my Cholestech L·D·X® System?
  • Answer: The Cholestech L·D·X® System requires no user calibration. The calibration information for running a test is encoded on the brown magnetic stripe on each cassette and is read each time a cassette is run.
  • Question: Do my patients need to be fasting for testing on the Cholestech L·D·X® System?
  • Answer: Patients do not have to be fasting for Total Cholesterol and HDL Cholesterol testing. Triglycerides and Glucose can increase markedly after eating. For accurate Triglyceride and Glucose results patients should be fasting for 12 hours before blood is drawn for testing. The Triglyceride result is used in calculating the LDL result so for accurate LDL results the patient should also be fasting.
  • Question: Why am I getting N/A for my HDL Cholesterol result?
  • Answer: Check to see what the Triglyceride result is. If the Triglycerides are > 7.34 mM/L the HDL cholesterol result will not be accurate and will be reported as N/A.
  • Question: Why am I getting N/A for my LDL result?
  • Answer: There may be several reasons for an LDL result of N/A. The LDL is calculated as follows: LDL= TC- ((TRIG/2.19)+HDL).
If the Triglyceride result is > 4.3mM/L, the calculated LDL will not be accurate and the LDL result will be reported as N/A.
If the TC, HDL or TRIG results are outside the measuring range of the instrument, the LDL will also not be calculated and will be reported as N/A.
  • Question: Why do I have to run the Optics Cassette and Controls?
  • Answer: As the L·D·X® is a photometer with very tight optical tolerances to ensure accuracy of lipid/glucose values reporting, it is important to run an optics check. This should be run:
    • Once a day before patient samples are tested
    • After the L·D·X® instrument has been moved
    • After a long period of inactivity
Quality Control refers to the testing done to show that a system is working properly and gives dependable results.
  • Question: How often do I have to run Quality controls?
  • Answer: In a laboratory running a large number of samples, QC samples would be run every day during batches of samples. In the small GP clinic situation, however, we recommend that a QC sample is run a minimum of once a week, and recorded in the QC log supplied with each L·D·X®. In addition, we recommend that you run controls:
    • With each new lot of cassettes
    • Any time you are not sure if the cassettes have been stored properly
  • Question: How long can I use my cassettes? How long can I keep my cassettes at room temperature?
  • Answer: As soon as you receive your cassettes they should be placed in the refrigerator. When stored, refrigerated at 2-8°C (36°-46°F), the cassettes are stable and can be used until the expiration date printed on the cassette pouch and box. Cassettes can be taken out of the refrigerator and stored at room temperature for thirty (30) days. Once the cassettes have been removed from the refrigerator, and have reached room temperature, the room temperature timing starts. The cassettes cannot be returned to the refrigerator to extend the dating to the expiration date on the label once they have reached room temperature.
  • Question: Can I use capillary tubes which are not Cholestech capillary tubes?
  • Answer: You should only use the Cholestech capillary tubes when collecting blood for testing on the Cholestech L·D·X® System. The Cholestech capillary tubes are calibrated to hold a sample volume of 35 ml. They also contain a lithium heparin anticoagulant which keeps the blood from clotting. Any other capillary tubes may not measure the correct amount or have the proper anticoagulant.
  • Question: An error message "Mag Read Error" appears on the L·D·X®. What does this mean?
  • Answer: This may be due to a defect on the magnetic stripe of the cassette. It may have a piece of dirt on it, so wipe the stripe with a soft tissue and restart the test, ensuring that the cassette is properly placed in the tray with the mag stripe to the right. If second test fails repeat with a new cassette. If message reappears call Customer Service.
  • Question: An error message "Tray Timeout" appears on the L·D·X®.  What do I do?
  • Answer: Press RUN, and if the cassette is jammed in the tray, the drawer will come out and you will be able to re-position the cassette flat in the tray and press RUN to start again.
Another reason could be that the microprocessor is confused because the buttons were pressed too quickly. Disconnect/reconnect the L·D·X® from the power supply. Repeat test with a new cassette. If message reappears call Customer Service.
  • Question: An error message "Reaction did not occur" appears on the L·D·X®.  What do I do?
  • Answer: this could be due to a number of things:
    • Insufficient sample volume was applied to the cassette due to air bubbles or incompletely filled capillary tube.
      • Repeat the test with a new cassette and fingerprick sample.
    • Insufficient sample volume reached the reaction pads due to high haematocrit of sample.
      • Repeat the test with a new cassette and fingerprick sample. If the message reappears, test patient by another method.
      • Haematocrit values of up to 52% do not affect results according to the manufacturer. The MDA report confirms that the samples they used had a haematocrit range of 33-54%; however the L·D·X® displayed an error message "No Reaction" for 3 patients who had haematocrits of 54%, 48% and 49%. The report confirms that at high haematocrit values, there is a negative correlation with bias in the HDLconcentration determined by the L·D·X®. However, neither the bias in total cholesterol nor in triglyceride, appeared to be associated with haematocrit level.
    • Improper sample collection (sample was either left in the capillary too long or the finger was milked).
      • Repeat test, paying close attention to proper technique.
    • Some patients may come to clinic relatively dehydrated because they have been fasting. This may be compounded if they are on antihypertensive medication (eg diuretics). We suggest that you ask them to have a glass of water and repeat the test after 15-30 minutes.
      • Repeat the test with a new cassette and fingerprick sample. If the message reappears, test patient by another method.
  • Question: An error message "WARN 1" is displayed on the L·D·X®.  What should I do?
  • Answer: The analyser is in an environment outside its proper temperature range- move it to another location or wait until the current location reaches acceptable temperature.
  • Question: An error message "WARN 2" is displayed on the L·D·X®. What should I do?
  • Answer: The Cassette expiration date has been reached.
      • Check the calendar in the analyser to make sure it is set correctly
      • Check the expiry date on the cassette pouch or box.
  • Question: An error message "WARN 3" is displayed on the L·D·X®.  What should I do?
  • Answer: There is a large difference between two readings that are used to calculate a mean value.
    • Repeat the test with a new cassette.
  • Question: An error message "Optics Test Fail" is displayed on the L·D·X®. What should I do?
  • Answer: There is a problem with the optical system of the analyser; Repeat the optics check with another optics check cassette. The analyser will now be de-activated and needs to be repaired.  Contact Customer Service.
  • Question: An error message "Bad Checksum" is displayed on the L·D·X®. What should I do?
  • Answer: This message indicates a defective ROM pack.  Contact Customer Service on 01793 840073.
  • Question: I have an LDX with version 1.4 ROM pack? Can I use the new Cholestech LDX Printer?
  • Answer: No. The Cholestech LDX Printer will work with LDX analysers from version 2.02.  For earlier versions of ROM packs, an upgrade is available for purchase through Point of Care Services Ltd.
  • Question: Will my Seiko printer work with the new version 2.02 ROM pack?
  • Answer: Yes, the Seiko printer will work with the new LDX Analyser version 2.02, without needing a ROM pack upgrade kit and the Seiko printer labels can still be purchased through Point of Care Services Ltd.
  • Question: What is ALT?
  • Answer: ALT (sometimes referred to as GPT) is Alanine Aminotransferase

    ALT is found in many tissues in the body, including kidney, heart, skeletal muscle, pancreas,  spleen, lung and red blood cells, but the largest concentration resides in the liver. Large quantities of ALT are released into the bloodstream when the liver is damaged. Therefore, the measurement of ALT is useful in the diagnosis and monitoring of hepatobiliary disease states such as chronic alcohol ingestion, exposure to hepatotoxins, liver damage caused by certain medications and following infections such as viral hepatitis. In viral hepatitis and other forms of liver disease or damage, levels of serum ALT may be elevated even before clinical signs and symptoms of the disease, such as jaundice, appear.

  • Question: Why measure ALT?
  • Answer: ALT levels increase rapidly when the liver is damaged by any cause including: hepatitis, hepatic cirrhosis, liver tumour, obstructive jaundice, Reye ’s syndrome or hepatotoxicity of certain drugs.

    Although it is present in skeletal muscle, heart and kidney tissue, it is primarily used to diagnose and monitor liver disease.

    A side effect of some lipid- lowering drugs (the statin group), in about 1%of patients receiving this therapy, is a persistent increase in serum ALT to more than 3 times the upper limit of normal. Patients who have experienced these increases usually have no symptoms.

    Therefore it is important to monitor liver activity in patients on lipid-lowering drug therapy.

    It is recommended that liver function tests be performed prior to the initiation of therapy and on a regular basis thereafter.

    ALT increases generally occur in the first 3 months of treatment with statins.

    Patients who develop increased ALT levels should be monitored until the abnormalities resolve. An increase in ALT to more than 3 times the upper limit of normal may be an indication for discontinuing drug therapy. ALT levels typically return to normal after drug therapy is discontinued.

    The FDA has also recently recommended that patients on the glitazone class of diabetes drugs (i.e.Actos ® and Avandia ®)have their liver function monitored every month for at least eight months and every 2 months for the remainder of the first year.

  • Question: What are the usual expected ranges for the Cholestech LDX ALT controls?
  • Answer: Level 1 (normal): 25-50 U/L; Level 2 (raised): 110-210 U/L (ranges will vary with batches)
  • Question: What is the expected value for ALT in normals?
  • Answer: Expected values in normals are 10-40 U/L, with values in men slightly higher than in women.
  • Question: What is the normal measuring range for ALT on the LDX?
  • Answer: The normal measuring range for ALT on the LDX is 10-400 U/L. Results outside the range will appear as <10 U/L or >400 U/L.
  • Question: How much higher than normal can ALT be raised?
  • Answer: Values may reach 20 to 100 times the upper limit of the reference range. Five-to 10- fold elevations of ALT occur in patients with primary or metastatic carcinoma of the liver. In infectious mononucleosis, with liver involvement, elevations may be up to 20 times the upper limit of the reference range.
  • Question: What factors cause raised ALT?
  • Answer: ALT may be slightly elevated in apparently healthy individuals due to the following factors: obesity, male gender, Hispanic or American-Indian descent, persons aged 25 - 35 years, alcohol use and long-term acetaminophen use.

    The highest elevations of ALT are found in cases of drug and viral hepatitis,acute heart failure and exposure to hepatotoxins such as carbon tetrachloride.

  • Question: On completion of the LDX ALT test the result showed up as N/A on the screen - why?
  • Answer: The kinetic characteristics of the enzymatic process for measuring aminotransferase are more temperature dependent than for measuring lipids.  It it very likely that the ALT test cassette was not brought out straight from the fridge and not allowed to stand at room temperature for a full 10 minutes.
  • Question: I have two MiniPet pipettes, a grey(50ul) and a brown (35ul) - which one should I use for what purpose?
  • Answer: You should only use the brown (35ul) for dispensing of the combined MAC control solutions.
  • Question: I only have a grey (50ul) MiniPet Pipette - what should I do?
  • Answer: For UK customers only:- call or email us at Point of Care Services and we will send you a replacement 35ul MiniPet Pipette.

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