HCV Log10...what does that mean?

[Perca05]

Hi all...my 4 week test results are back and they all look great.  I wanted to know what the HCV Log10 is?  If the Harvoni kills the virus, will this drop to 0?  My current reading is:  HCV log10 1.301 log10 IU/mL

thanks!

[Mike]

Reporting a viral load in logs is an easier way to gauge treatment effectiveness.

Here's a useful chart that coverts log to viral load:

Log10   copies/mL
7   10,000,000
6.9   7,943,282
6.8   6,309,573
6.7   5,011,872
6.6   3,981,072
6.5   3,162,278
6.4   2,511,886
6.3   1,995,262
6.2   1,584,893
6.1   1,258,925
Log10   copies/mL
6   1,000,000
5.9   794,328
5.8   630,957
5.7   501,187
5.6   398,107
5.5   316,228
5.4   251,189
5.3   199,526
5.2   158,489
5.1   125,893
Log10   copies/mL
5   100,000
4.9   79,433
4.8   63,096
4.7   50,119
4.6   39,811
4.5   31,623
4.4   25,119
4.3   19,953
4.2   15,849
4.1   12,589
Log10   copies/mL
4   10,000
3.9   7,943
3.8   6,310
3.7   5,012
3.6   3,981
3.5   3,162
3.4   2,512
3.3   1,995
3.2   1,585
3.1   1,259
Log10   copies/mL
3   1,000
2.9   794
2.8   631
2.7   501
2.6   398
2.5   316
2.4   251
2.3   200
2.2   158
2.1   126
Log10   copies/mL
2   100
1.9   79
1.8   63
1.7   50
1.6   40
1.5   32
1.4   25
1.3   20
1.2   16
1.1   13
Log10   copies/mL
1   10
0.9   8
0.8   6
0.7   5
0.6   4
0.5   3
0.4   3
0.3   2
0.2   2
0.1   1

Your viral load is 20.

Best wishes, Mike

[Perca05]

Thank you!  That answered my question.

[Bituman]

"Log" means the common logarithm of a number in base 10 arithmetic.  Ask yourself a question:  what number do I have to raise 10 to, to get the number in question.  You can look at Mike's table and spot the easy examples.  For instance, what number do you have to raise 10 to, to get 1,000,000?  The answer from the table is 6.  In other words, 10 raised to the 6th power equals 1,000,000 so the log of 1,000,000 is 6.  In base 10, you can count the number of zeros to get the log.  For example, the log of 10,000 is 4.

So in your example, you raise 10 to the 1.301 power.  My calculator says 20, same as Mike told you.  So your VL is 20, which is a super good number.  Congratulations! 

It seems kind of silly for your lab to report the log of your VL.  I think they do this because before successful treatments were available, it was easier for doctors to converse in terms of log of VL because the numbers were otherwise so impossibly high.  People don't easily comprehend such big numbers.  Your lab report is a kind of leftover from those days. 

To answer your other question, you will never see zero expressed as a logarithm because it doesn't exist.  Actually, the last few numbers in that table are wrong.  The log of 1 is zero, not 0.1.   

Scientists and engineers use log transformations to make their data more managable and more easily understood.  Lets say a hepatologist wanted to plot viral load of her patient versus number of orange pills taken.  That would be easy, except as we all know, the VL drops pretty quickly so the scale on y-axis would have to be impossibly large to get numbers like 1 million and 100 and 10 all on the same scale.  So to solve this problem, the hepatologist plots the log of these numbers, 6, 2, and 1, and the data all easily fits on the same scale. 

When I started high school we used log charts from the Navy to do our homework.  Then those of us who were especially nerdy started using slide rules to get logarithms.  That lasted a year or two into college at which time we all started using electronic calculators.  Now of course, spreadsheets like Excel do it for you. 

This is probably more than anyone really cares to know.  Obviously a slow night here in the desert.

Bob

[BubbaT]

mike, what do these results mean? I had this test done 6-14

 HCV  RNA. Quantitative  real time.    2289864.           <15 IU/ml
 HCV. RNA.  ".                  ".    ".        6.36.                 < 1.18 log IU/ml

[Mike]

The HCV  RNA. Quantitative  real time  2289864., means you have a viral load of 2,289,864 per Iu of blood. The second number expresses this in log form.

Mike

[StaciH]

'M

"Log" means the common logarithm of a number in base 10 arithmetic.  Ask yourself a question:  what number do I have to raise 10 to, to get the number in question.  You can look at Mike's table and spot the easy examples.  For instance, what number do you have to raise 10 to, to get 1,000,000?  The answer from the table is 6.  In other words, 10 raised to the 6th power equals 1,000,000 so the log of 1,000,000 is 6.  In base 10, you can count the number of zeros to get the log.  For example, the log of 10,000 is 4.

So in your example, you raise 10 to the 1.301 power.  My calculator says 20, same as Mike told you.  So your VL is 20, which is a super good number.  Congratulations! 

It seems kind of silly for your lab to report the log of your VL.  I think they do this because before successful treatments were available, it was easier for doctors to converse in terms of log of VL because the numbers were otherwise so impossibly high.  People don't easily comprehend such big numbers.  Your lab report is a kind of leftover from those days. 

To answer your other question, you will never see zero expressed as a logarithm because it doesn't exist.  Actually, the last few numbers in that table are wrong.  The log of 1 is zero, not 0.1.   

Scientists and engineers use log transformations to make their data more managable and more easily understood.  Lets say a hepatologist wanted to plot viral load of her patient versus number of orange pills taken.  That would be easy, except as we all know, the VL drops pretty quickly so the scale on y-axis would have to be impossibly large to get numbers like 1 million and 100 and 10 all on the same scale.  So to solve this problem, the hepatologist plots the log of these numbers, 6, 2, and 1, and the data all easily fits on the same scale. 

When I started high school we used log charts from the Navy to do our homework.  Then those of us who were especially nerdy started using slide rules to get logarithms.  That lasted a year or two into college at which time we all started using electronic calculators.  Now of course, spreadsheets like Excel do it for you. 

This is probably more than anyone really cares to know.  Obviously a slow night here in the desert.

Bob

[dragonslayerinprogress]

What does HCV log 1 .       Result NP  mean
Is that a negative positive?