Essential amino acid requirements

Stuart Dunn dunns99 at
Thu Dec 16 12:36:39 EST 1999

pathos wrote:
> In article <3858BEBC.1EDD at>, Stuart Dunn <dunns99 at> wrote:
> > > 2) Calcium levels have nothing to do with pH of the urine.
> > They do effect the pH level of urine. The breakdown of protein produces
> > acids which are then excreted through the urine. Since the pH level of
> > urine must be maintained, the body excretes more calcium in the urine.
> > Cysteine and Methionine are the amino acids that increase calcium loss
> > when consumed to excess, and most people get lots of these two amino
> > acids from nonvegan foods. I did find some interesting information on
> > protein, and I'll post it sometime today.
>    1)Proteins are not broken down in the kidney.  
You think I didn't know that? I am not refering to protein digestion. I
was refering to the fact that amino acid breakdown produces urea and
other acids that are excreted through the urine.
Digestion involves
> adsorbtion of substances through the gut.  
That's right.
The liver is the main player in
> the disemination of nutrients to the rest of the body.  The kidney job is
> to maitain a proper electrolitic balence in the plasma.  The liver is
> responsible for the ecretion of proteins, amino acids, bilirubin and
> others thruogh the bile which is dumped into your lower intestine.
>    If proteins or amino acids appear in significant quatities (detectable
> quatities by colormetric tests: sensitivity ~ .1uM) in the urine then that
> is gernerally considered to be evidence of glomerular damage.  
I wasn't refering to amino acids in urine, I'm talking about their
> exception is peaple that have just finished heavy extended
> exerciseimmediately preceeding the urine sample..
>    2) calcium is readsorbed by in the distal tubules.  The rate of
> readsorbtion is dependant on the plasma levels of calcium.  The main
> player here is a hormone called PTH.  As PTH levels increase the amount of
> calcium that is activly readsorbed by the distal tubules increses and the
> calcium levels in the plasma increase.
So are you saying that protein, salt, alcohol, and caffeine intake don't
effect calcium losses through urine?
  Once again, I emphasize the fact
> that if the body needs to conserve calcium, it will.  The PTH also
> increases the amount of calcium that is readsorbed in the gut which is
> most significant.  PTH will inhibit the readadsorption of phosphate in the
> proximal tubules.  The net effect of this action is for the plasma calcium
> NOT to precipitate in the tissue in the form of calium phosphate.  PTH
> also inhibits the readsorption of Bicarbonate  and sodium.  This allows
> for the prevention metabolic alkalosis which could result from the
> release  of Bicarbonate when the hydroxyapetite is disolved in the bone.
> BTW, normal urine has a pH range of 5-7.  That is a 100 fold difference in
> HDROGEN ION CONCENTRTION from high to low.  This dimonstrates that pH is
> not all that tightly regulated as you seem to make it out to be
Yes, I know that a pH range of 5-7 is that big a difference. Even so,
the if the pH level of urine is too high or too low, it would cause a
> Peter Pediaditakis
> Dept. of Pathology
> University of Pittsburgh

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