web-HUMAN- Basic Quantitative Renal Calculations

I. Brief review of principles

a. Determination of Excreted load (mg/min)

Excreted = Filtered load - Reabsortion + Secretion [all are in mass flow units e.g. mg/min]

b. Determination of mass flows

Since C = Mdot/Qdot (where Qdot = dQ/dT)

Then Mdot = C * Qdot

Thus volume flow (Qdot ) and plasma or urine concentrations (C) are needed to determine mass flows (Mdot). (see table layout)

II. A list of some useful HUMAN variables (use 'List all variables' for more)

 GFR U24 

III. Urine N and values

Use Kidney Charts option to only read out values for urine urea N and no other variable.

- you may not use the Kidney charts for Na, K, etc. values. Instead, obtain them directly in a HUMAN experiment via <View variable> or placing relevant variables in <Tables>.

Explore use of a 24 hour urine collection. Values at 25+ hours can be read out in 24 hour urine collection under Charts.... .

IV. Acid handling (optional)

How much acid is (reabsorbed/secreted) each day?

-determine acid excretion per min.. Calculate acid excretion/day. Compare with value obtained via plasma/urine pH difference for the 24 hour period.

recall: pH = - log [H+]

V. Some helpful tips (READ THIS before you begin to work on the table!)

	- watch your units carefully

	- you don't need to convert weights to meq.
		simply do calculations in G/24 Hrs or as appropriate

	-units of % are "per 100"
	e.g. 20 vol.% O2A is 20 ml O2/100 ml blood
	e.g. 15.4 G% is 15.4 grams per 100 ml of blood
	note: a dl (= deciliter) which = to 1/10 L (or 100 ml)

	- milliequivilents may be thought of as electrical' moles
	e.g.	1 mM Na+ => 1 meq. Na+
		1 mM Ca2+=> 2 meq. Ca2+

	EXBIC is really zero. It has a negative value in HUMAN because normal net acid excretion 
is positive and therefore base excretion is 'negative'. That is, base is conserved. Apologies!

	Scientific notation in FORTRAN and HUMAN
		scientific	-1.0*10-1 = 	0.1
		in HUMAN	-1.0*E-01 =	0.1

======> Click here to load the data table for this exercise. (formatted in html for printing)