Understanding Blood Test Results in Adrenoleukodystrophy

Understanding Blood Test Results in Adrenoleukodystrophy

One of the first diagnostic tests performed when an individual shows symptoms of adrenoleukodystrophy (ALD) — a disease characterized by the build-up of saturated very-long-chain fatty acids (VLCFAs) — is a blood test.

If your doctor suspects that you have ALD and orders a blood test, the results are important to estimate the severity of the disease.

Complete blood count

Apart from measuring VLCFA levels, your doctor may also recommend a complete blood count (CBC) to view your overall blood profile, including the number of red blood cells, white blood cells, and platelets, and the level of hemoglobin.

Results can differ between labs

Factors such as the instruments and reagents used to perform blood tests can vary from one diagnostic lab to another. Even sample handling procedures across labs are not necessarily the same. Therefore, if you have your blood test repeated, you might not see the same values in your report. Each lab has a standardized reference range for every test so first compare your results with the ranges provided in your report.

High VLCFA levels

Estimating VLCFA levels in the blood is the first step in the diagnosis of ALD. The normal levels of different VLCFA types are as follows:

  • C26:0 — 0.23 (+0.09) microgram per milliliter
  • C24:0 / C22:0 ratio — 0.84 (+0.10)
  • C26:0 / C22:0 ratio — 0.01 (+0.004)

The number indicated after ‘C’ represents the position of the carbon atom in each type of VLCFA molecule. For more information, refer to our page about blood tests.

These values are significantly elevated in men with the disease, who have higher levels than female carriers of the disease. The levels in affected men and carrier women compared to the normal range are shown in this table.

Low levels of cortisol

The blood test report may also include information about the levels of cortisol and electrolytes such as sodium and potassium, and can help confirm the diagnosis of a type of ALD known as Addison’s disease, which constitutes about 10% of ALD cases.

Cortisol levels are influenced by many factors such as gender, age, testing method, and even the timing of the test. Normal cortisol levels are in the range of 10 to 20 micrograms per deciliter from 6 am to 8 am, while the levels range from 3 to 10 micrograms per deciliter around 4 pm.

Very low levels of cortisol along with low sodium and high potassium levels are indicative of Addison’s disease. Use only the lab’s reference ranges to determine whether your levels fall in the normal range.

Genetic testing

A blood sample may also be used for a genetic test to look for changes in the ABCD1 gene, the gene that is mutated in ALD. Detecting mutations in this gene can help doctors reach a definitive diagnosis, although the absence of mutations does not exclude an ALD diagnosis.


Last updated: Oct. 18, 2019


Adrenoleukodystrophy News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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Özge has a MSc. in Molecular Genetics from the University of Leicester and a PhD in Developmental Biology from Queen Mary University of London. She worked as a Post-doctoral Research Associate at the University of Leicester for six years in the field of Behavioural Neurology before moving into science communication. She worked as the Research Communication Officer at a London based charity for almost two years.

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