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

Uric acid concentrations in blood plasma above ( >6mg

/dL) and below (<3mg/dL) the normal range are known, respectively, as hyperuricemia and hypouricemia.

Male: 237.9 ～ 356.9μmol/L(4 ～ 6mg/dL),Female: 178. 4 ～ 297.4μmol(3 ～ 5mg/dL).

In human blood plasma, the reference range of

uric acid is

This range is considered normal by the American Medical Association.

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.

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).

Gout

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.

urate crystal

Uric Acid Crystals Under Polarizing Light Microscopy

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 x-ray by their displacement of the surrounding kidney tissues. Some patients with gout eventually get uric kidney stones

One treatment for gout has been administration of Lithium salts; lithium urate is more soluble.

How to treat?

Uric acid + H2O + O2 Allantion + CO2 + H2O2

uricase

principle

H2O2 + 4-AAP+ DHBSPOD

red quinone complex+H2O( peroxidase )

B S T

Working(ml) 1.0 1.0 1.0

Standard solution(μl)

_ 20 _

Sample(μl) _ _ 20

Mix, 37oc,10min

ddH2O(ml) 0.5 0.5 0.5

Set zero with B , 510nm, At , As

[PROCEDURE]

[ CALCULATION ]

C = At

As×Cs

[ Reference range]

160 μmol/L ~360 μmol/L

( Cs = 400μmol/L )