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Extraordinary high blood melatonin levels

Posted by DKennaway on 05 Sep 2020 at 01:01 GMT

The serum melatonin levels reported in this paper are approximately 1000 times higher than expected at the time of day the samples were collected (around midday). I have no confidence in any conclusions drawn about the changes in melatonin. The cause is clearly that the ELISA used is not specific for melatonin. See Kennaway J Pineal Res 2020 Apr 13;e12657.doi: 10.1111/jpi.12657.

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RE: Extraordinary high blood melatonin levels

MoezFaris replied to DKennaway on 18 Sep 2020 at 05:49 GMT

Dear Sir
Thanks for your comment
After doing our inspections on the original data, laboratory procedures, used kits, statistical analyses and data presentation and results tabulation, we found that the comment raised by the respected reader is right, and that the mistake was found in reporting the data in the final draft, rather than in the assay kit or procedure used, or in the statistical analysis applied. While admitting that the error was found in the transfer of the results into the manuscript table, we assure that the original data were sound and the raised issue was only related to the end transfer of results to the final tables. This is reinforced by the text description for the study results pertaining to serum melatonin, where the study described a significant reduction in melatonin at the end of the fasting month (T2).
We noticed a typo in the melatonin level in T2 in Table 3; the “decimal point” was dropped by mistake. Instead of writing the melatonin level and SD as 0.7483 and 0.3811, respectively, it was mistakingly written as 7483 and 3811.
Therefore, we would like to publish the correction of the values in Table 3.
The correction will be as follows:
Parameter T1 T2 P-value
Mean SD Mean SD
Serum melatonin (pg/ml) 1.2 0.2605 0.7483 0.3811 **

Thanks for your important notice

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RE: RE: Extraordinary high blood melatonin levels

DKennaway replied to MoezFaris on 28 Jun 2021 at 01:51 GMT

You indicated that the values should now in fact be means of 1.2 and 0.74 pg/ml
See table below Parameter T1 T2 P-value
Mean SD Mean SD
Original Serum melatonin (pg/mL) 1.2 260.5 748.3 381.1 **
Should have been Serum melatonin (pg/mL) 1231 260.5 748.3 381.1
Response to comment: now should be
Serum melatonin (pg/mL) 1.2 0.2605 0.7483 0.3811

The assay that you used has a sensitivity of 162 pg/ml and so it would be impossible to record such low values as you now want to use.
I am led to believe that the original mean values were essentially correct, i.e 1231 pg/ml and 748 pg/ml. These are the values you get from your published spreadsheet.

On looking at the spreadsheet there are some other anomalies that require an explanation.
It would appear that when subjects did not have melatonin assayed, the group means were inserted instead. This will change the SD. Not good.
For T2, there are 9 entries of 10 pg/ml! What do they mean? They will distort both the mean and SD
For T1 subjects 149 &133, 110 & 17, 120 & 116, 119 & 118 and 15 & 136 have identical values to 1 decimal point! This is impossible and an explanation is warranted.

Finally, you may not be aware that Abcam have stated on their website that their Melatonin ELISA Kit (ab213978) is “Currently unavailable. We are re-evaluating this product to ensure it meets our strict quality criteria. Unfortunately it will not be available to order during this time.”

This would indicate that you have in good faith purchased and used a kit that is defective and obtained results that are not sound.

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