drat it ! I use 2.19 !
am I going to have to back calculate all my LDLs for the last 5 years ?
With best wishes
Richard
-----Original Message-----
From: Neely, Dermot [mailto:[log in to unmask]]
Sent: Tuesday, April 30, 2002 10:50
To: [log in to unmask]
Subject: Re: Need information on Calculated Values and Ratios
At the risk of sounding like an insufferable pedant, I believe the factor
for calculation of VLDL-C according to the Friedewald equation (quoting as 5
for measurements in mg/dL)in mmol/L is closer to 2.18 than 2.22 as stated.
It may be calculated from the conversion factors for mg/dL to mmol/L for
chol (0.02586) and triglyceride (0.01129) as follows:
VLDL-C to Total Triglyceride ratio (mmol/L) = (0.01129 x 5)/0.02586 = 2.183
Use of the incorrect factor will, in fact, only make a small difference to
calculated LDL-C which will be overestimated by 0.04 mmol/L if the equation
is applied as intended with triglyceride <4.5. Perhaps we should try to keep
it simple and use 2.2
******************************************
Dr RDG Neely
Consultant Chemical Pathologist
Department of Clinical Biochemistry
Newcastle upon Tyne Hospitals NHS Trust
Royal Victoria Infirmary
Newcastle upon Tyne NE1 4LP
Tel. 0191 2824554 Fax. 0191 2820381
******************************************
The opinions expressed in this message are those of the author and do not
reflect those of NUTH NHS Trust unless stated.
The contents of this E-mail are intended for the addressee only.
-----Original Message-----
From: Trevor Walmsley [mailto:[log in to unmask]]
Sent: 29 April 2002 22:15
To: [log in to unmask]
Subject: Re: Need information on Calculated Values and Ratios
BUN/Creatininine Ratio
- we don't calculate this ratio if we did it would be a mole ratio i.e.
urea and creatinine in the same molar units
Calculated LDL:
we use LDL Chol = Total Chol - HDL Chol - (Trigs/2.22)
see http://www.cdhb.govt.nz/chlabs/tests/4042.htm
It is based on the avearage VLDL trig/chol ratio of VLDL of 2.22 and hense
does not work for type III patients since they have cholesterol rich VLDL.
===========================================================
>>> Ashok Sawhney <[log in to unmask]> 26/4/02 8:39 am >>>
Dear Members,
I need information on how laboratories in Canada and European countries
calculate the following parameters:
BUN/Creatininine Ratio
Because Urea Nitrogen values are reported in mmol/L but creatinine
is reported in micromoles/L, do you calculate the ratio of mmol/L to
umol/L or you first convert the creatinine from micromoles/L to mmol/L
and then determine the ratio.
Calculated LDL:
In USA using the conventional units, mg/dL, for Cholesterol,
HDL-Cholesterol, and Triglycerides, we calculate LDL-Calc using
following equation:
LDL-calc (mg/dL) = [Total
Chol]-[HDL-Chol]-{[Trig]/5}
Because SI units are in mmol/L, what equation is employed to calculate
the LDL-Calc in mmol/L. I have come across the following relationship:
LDL-Calc (mmol/L) = [Total Chol] - [HDL-Chol] -
{0.46x[Trig]} All units are mmol/L
Is this relationship still used?
Calculated Osmolality:
Using the values of Sodium (mmol/L), Glucose (mg/dL), and BUN (mg/dL),
in the US Osmolality is calculated using the following equation:
Osmolality-Calc (mOsm/Kg) = 1.86x[Na] + 0.056x[Glu] +
0.36x[BUN] + 9
How do european labs calculate the Osmolality, when the reported units
are in SI Units, Sodium (mmol/L), Glucose (mmol/L), and BUN (mmol/L)?
are the SI units still mOsm/Kg or it is designated something else. I
have been also been "told" that the SI unit for Osmolality is mmol/Kg.
is this correct? Can you provide any reference(s) for the other
relationship(s) that takes into account the Na, Glu, and BUN units in
mmol/L.
Any help in this matter will be highly appreciated.
Thank you
Ashok Sawhney, Ph.D.
Careside, Inc.
Culver City, CA, 90230
USA
[log in to unmask]
"We tortured the data until it confessed."
Trevor Walmsley, Canterbury Health Labs, Christchurch, New Zealand.
Phone: (0064 3) 364 0326 Fax:Phone: (0064 3) 364 0320
eMail: [log in to unmask]
Internet: http://www.cdhb.govt.nz/chlabs/staff/trevorw.htm
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