Q. What are the conditions that can cause a fluctuation in the ALP levels?

Answered by
Dr. Basuki Nath Bhagat
and medically reviewed by iCliniq medical review team.
This is a premium question & answer published on Apr 16, 2022

Hello doctor,

I need your help reading an ALP isoenzyme test report. What does it mean by percentage and fraction? Is it possible for the percentage to be normal and the fraction abnormal?

Please help.



Welcome to

I have read your query and can understand it.

ALP (Alkaline phosphatases) are a group of isoenzymes located on the outer layer of the cell membrane. The normal serum alkaline phosphatase consists of many distinct isoenzymes found in the liver, bone, placenta, and less commonly, in the small intestine.

The majority of alkaline phosphatase in serum (more than 80 %) is released from the liver and bone, and small amounts are from the intestine.

Following are the physiological conditions that can cause fluctuation in the value of the alkaline phosphatase enzymes without any obvious clinical diseases;

1) Patients over age 60 can have a mildly elevated alkaline phosphatase (which is one to one and a half times normal).

2) Individuals with blood types O and B can have an elevation of the serum alkaline phosphatase after eating a fatty meal, due to the influx of intestinal alkaline phosphatase into the blood.

3) It is also elevated in children and adolescents undergoing rapid bone growth because of bone alkaline phosphatase and in late normal pregnancies due to the influx of placental alkaline phosphatase.

Following are the ways to differentiate the source of alkaline phosphatase in case the value of alkaline phosphatase increases more than the upper limit range of the laboratory value;

1) If the elevated serum alkaline phosphatase is associated with deranged liver enzymes and bilirubin levels, then most likely the elevated alkaline phosphatase is of liver origin.

2) If the elevated serum alkaline phosphatase is the only abnormal finding in an apparently healthy person, or if the degree of elevation is higher than expected, identification of the source of elevated isoenzymes is helpful, which is done by fractionation of the alkaline phosphatase by electrophoresis (a laboratory method used to separate the DNA, RNA and proteins based on their size and electrical charge).

3) Other conditions that cause elevations of the alkaline phosphatase include Hodgkin's disease, diabetes, hyperthyroidism, congestive heart failure, amyloidosis, and inflammatory bowel disease. These help the clinician to correlate with the value of alkaline phosphatase based on the available medical history, other lab tests, imaging tests and diagnose the patient's condition.

I hope this helps.

Please revert with the laboratory report to interpret it better.

Hello doctor.

Thank you for the detailed reply.

In the test reports, I noticed that they have mentioned a percentage of the liver enzyme and a fraction of the liver enzyme. If the percentage is normal and the fraction is not what does that mean? Also, I have attached the report. Please provide your explanation on it.



Welcome back to

To help you understand the concept of percentage, its absolute increase, and the fraction of any component or parameter better, I will give you an example based on an assumption.

Let us say protein A is having a normal value of 10 (range 0 to 10) in the serum among the total proteins, and the normal value of total protein is up to 100. So, the percentage of protein A would be normal.

Now, due to an illness, the total protein has raised to 200, and protein A has also raised accordingly contributing to an increase in total protein. For example, let us say protein A has now increased to 20 (range 0 to 10).

Here, the percentage of protein A is still 10 % by calculation but, actually, protein A has increased in absolute value, which is abnormal.

Reading the percentage value in the second scenario does not hint that there is an ongoing problem but actually there is an increase in the value of protein A which is reflected by the absolute number or its fraction among the total.

So, in the above blood test report, you have attached (attachment removed to protect the patient's privacy) the fraction of liver alkaline phosphatase has increased above the upper limit but percentage-wise it is in a normal range.

What about other liver functions, liver enzymes, and bilirubin levels? Have you taken them? If so, kindly attach those reports for further reference.

I hope this helps.

Kindly revert in case of further queries.

Hello doctor,

Thank you for the reply.

I am a 66-year-old female. A few years back I had an ALP level of 109 U/L and two years ago my ALP level was 163 U/L. All my other enzymes tests, GGT, bilirubin, and ultrasound were normal. My next ALP level was 138 U/L followed by 137 U/L the next time. A year later my ALP is 163 U/L and all other liver enzymes and lipids are normal. After two months my ALP dropped to 134 U/L with the same isoenzymes level. All the other tests are normal and I do not have any symptoms.



Welcome back to

I read your query and can understand your concern.

As you say your recent ALP level is 134 U/L, it is mildly high compared to the upper limit value. But, as I mentioned previously, patients over age 60 can have a mildly elevated alkaline phosphatase, so, an extensive evaluation is often not needed in those patients who have only a mild elevation of serum alkaline phosphatase (less than 50 % elevation).

As the other LFT (liver function tests) and imaging modalities are normal in your case, I suggest you not worry and do periodic monitoring of the serum liver function tests.

Also, the fractionation of the isoenzymes of alkaline phosphatase has revealed bone isoenzymes as normal and so it is not related to bone pathology.

Please revert with information on if you have any chronic conditions like diabetes or hyperthyroidism?

Hello doctor,

Thank you for the reply, it was very helpful. I need your help on the below concerns as well;

Does the elevated isoenzyme level need to be concerned about? Is not the increased isoenzyme levels an indication of a disease? Or is it because the elevation is within 134 U/L that it is not a concern? Is there a particular reason for the sudden increase in the two-year interval? I am a B blood type but no intestinal was indicated, why is that so? Does ALP rise and fall by 30 points? Why was the GGT normal previously and isoenzymes negative for bone now? If that is the case would not I be sick by now?



Welcome back to

1) The serum level of alkaline phosphatase can fluctuate when the test is done from time to time.

2) GGT (gamma-glutamyl transferase) is one of the enzymes reflecting cholestasis of the liver. There is no reason to find why it is normal and it is good that the value is normal.

3) The present mild elevated value of alkaline phosphatase is not of bone origin as the value of bone alkaline phosphatase is in the normal range and it rules out that there is no bone-related pathology.

4) I do not think it is an indication of the disease process as the values are not consistently high every time the test is done and it has fluctuated from time to time.

5) So, I think an extensive evaluation is not needed at this value and you must be observed clinically with periodic monitoring of serum liver biochemical tests.

6) Also, what is your treating physician's opinion regarding it?

I hope I have answered your query.

Hi doctor,

Thank you for the reply.

I was told by my former doctor to consult a hepatologist, but my current doctor told me that 163 U/L is not high for an older person. As I have had too many opinions, I do not know what to think.



Welcome back to

I too think that the elevation of alkaline phosphatase is mild and extensive evaluation is not needed for this value, you just need to get tests from time to time.

Please do follow-up if you have any further queries.

Hello doctor,

Thank you for your detailed reply.



Welcome back to

You are most welcome.

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