Transcript Uric acid

Uric acid
xiaoli
Uric acid is produced by xanthine oxidase from xanthine
and hypoxanthine, which in turn are produced from purine.
Mainly in liver, kidney, intestine.
Uric acid
In human blood plasma, the reference range of uric
acid is
Male: 237.9～356.9μmol/L(4～6mg/dL),
Female: 178. 4～297.4μmol(3～5mg/dL).
This range is considered normal by the American
Medical Association.
Uric acid concentrations in blood plasma above
( >6mg/dL) and below (<3mg/dL) the normal range are
known, respectively, as hyperuricemia and hypouricemia.
The reasons of hyperuricemia
● Produce too much uric acid
(about 10% of cases)
● unable to excrect enough uric acid into
the urine (about 90% of cases)
Produce too much uric acid
About 10% of cases of gout are due to overproduction of
uric acid. When uric acid is overproduced, it is high not only in
the blood but in the urine.
● Some people overproduce uric acid due to a genetic defect in
an enzyme in the purine breakdown pathway which leads to
overactivity of this pathway.
● Since cells contain DNA, and DNA contains purines, anything
that increases the breakdown of cells in the body can lead to
more uric acid .
For example, if a patient is receiving chemotherapy for a tumor, as
the treatment kills the tumor cells, hyperuricemia can develop as a result
of the breakdown of the purines from those cells.
● Foods can also lead to overproduction of uric acid, such as
meats and beans and beer, which contain high levels of purines.
unable to excrect enough uric acid
into the urine
● The most common is a genetic defect in substances
referred to as organic anion transporters in the kidney,
which leads to an excessive reabsorption of uric acid from
the kidney—and thus too much uric acid in the blood.
● However, a defect in excretion of uric acid can also
occur due to medications, such as diuretics, low dose
aspirin, or alcohol.
● Defective uric acid excretion also occurs when the
kidneys are functioning poorly.
Gout
Excess serum accumulation of uric acid can lead to a
type of arthritis known as gout. This painful condition is
the result of needle-like crystals of uric acid precipitating
in joints and capillaries.
Gout can occur where serum uric acid levels are as low
as 6 mg/dL (~357µmol/L).
Man get gout more than women, and at younger ages,
the male to female ratio is 9:1. The most common age
of onset is from age 40- 60 years.
Uric Acid Crystals Under
Polarizing Light Microscopy
urate crystal
gouty arthritis
Toe with Acute Attack of Gout
uric kidney stones
Saturation levels of uric acid in blood may result in one form of
kidney stones when the urate crystallizes in the kidney.
These uric acid stones are radiolucent and so do not appear on an
abdominal plain x-ray or CT scan. Their presence must be diagnosed by
ultrasound for this reason.
Very large stones may be detected on xray by their displacement of the surrounding kidney tissues. Some
patients with gout eventually get uric kidney stones
How to treat?
One treatment for
gout has been
administration of
Lithium salts; lithium
urate is more soluble.
principle
uricase
Uric acid + H2O + O2
Allantion + CO2 + H2O2
POD
quinone complex+H2O
H2O2 + 4-AAP+ DHBS( peroxidase red
)
[PROCEDURE]
B
S
T
Working(ml)
1.0
1.0
1.0
Standard
solution(μl)
Sample(μl)
_
20
_
_
_
20
Mix, 37oc,10min
ddH2O(ml)
0.5
0.5
Set zero with B , 510nm, At , As
0.5
[ CALCULATION ]
At
C=
×Cs
As
( Cs = 400μmol/L )
[ Reference range]
160 μmol/L ~360 μmol/L