1

Urinalysis. Urine sediment

Seminar No. 13

2

Q. 2

Test for Glc, KB

3

Test for Reagent(s) / Principle Problem(s)

Glucose glucoseoxidase + peroxidaseascorbate false negativity

peroxides false positivity

KBsodium nitroprusside

Na2[Fe(CN)5NO]fresh sample needed to prevent the decarboxylation of acetoacetate

4

glucose + O2 gluconolactone + H2O2

H2O2 + H2A 2 H2O + A

glucoseoxidase

peroxidase

colourless chromogen

coloured product

colourless colourless colourless colourless

colourless colourless

Enzymatic test for glucose

5

Test for blood (Hb), bilirubin

6

Test for Reagent(s) / Principle Problem(s)

Bloodperoxidase like activity of heme

Fe salts false positivity

Bilirubin

Ubgdiazonium salts give coloured azo-compounds R-N=N-R’

fresh sample needed

7

Test for proteins, nitrites

8

Test for Reagent(s) / Principle Problem(s)

ProteinsProtein error of some acid-base indicators

Sensitivity mainly for albumin

Nitrites

Ar-NH2 + HNO2 + HCl

Ar-NN+ Cl- + 2 H2O

H-Ar’

Ar-N=N-Ar’ + HCl

•Fresh urine needed

•Absolutly clean vessels

•4 h urine retention in bladder

•No antibiotics

•High ascorbate false negativity

9

Urine sediment

• suspension material obtained by centrifugation of fresh

urine sample under defined condition

• semiquantitative quantitative

• chemical sediment – crystals of various compounds (salts)

• biological sediment – cells (RBC,WBC), casts, bacteria

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Factors involved in renal stones formation

• increased concentrations of certain ions (Ca2+, Mg2+ ...)

• extreme values of pH of urine

• low intake of fluid (low diuresis)

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Insoluble compounds

CompoundInsolubility pH range

Acid Neutral Alkaline

Uric acid

Ammonium hydrogen urate

Calcium oxalate

Calcium hydrogen phosphate

Hydroxyapatite

Ammonium magnesium phosphate

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Write formulas

Calcium oxalate

Calcium hydrogen phosphate

Hydroxyapatite

Ammonium magnesium phosphate

13

Calcium oxalate Ca(COO)2

Calcium hydrogen phosphate CaHPO4

Hydroxyapatite Ca5(PO4)3OH

Ammonium magnesium phosphate NH4MgPO4

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Uric acid (lactim) is a diprotic acid

N

N

N

NH

OH

HO

OHN

N

N

NH

OH

HO

ON

N

N

NH

OH

O

O

uric acid hydrogen urate urate

pKA1 = 5.4 pKA2 = 10.3

2,6,8-trihydroxypurine

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Mineralogical name Chemical name

Weddellit calcium oxalate dihydrate

Whewellit calcium oxalate monohydrate

Struvit magnesium ammonium phosphate hexahydrate

Brushit calcium phosphate dihydrate

Uricit uric acid

16

Q. 7

17

Q. 8

18

Bacterial urease catalyzes the hydrolysis of urea

H2N-CO-NH2 + H2O 2 NH3 + CO2

NH3 + H2O NH4+ + OH-

alkaline urine precipitation of CaHPO4

ammonia

weak base

ammonium

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Q. 10

20

• oxalates

• see the table in lab manual, p. 109

There are three sources

of oxalic acid in

the body

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Three sources of oxalic acid in the body

60 % catabolism of glycine and ethanolamine

30 % catabolism of ascorbate

10 % plant food

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Glycine oxalate

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COOHCH2

NH2

COOHCH

NHFAD FADH2

O2H2O2

H2O

NH3-H

C

O O

C

OH

glyoxalát

HO

C

O O

C

OHoxalát

H

C

O

S CoA-CO2

formyl-CoA

oxid.

glyoxylate

oxalate

iminoacetate

Glycine oxalate

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Ethanolamine oxalate

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Content of oxalic acid in some plant foods

Food Content (mg/kg)SpinachChard (mangold)RhubarbTeaCocoaBambooBeetrootCabbageWheat flourBrocoliTomatoes

5000 - 100005000 - 90002000 - 96006000 - 70003000 - 45001600 - 4500300 - 1400100 - 1200400 - 750100 - 50050 - 100

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Chard (mangold)

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Rhubarb

• a herb with long reddish leaf-stalks, rich in oxalic acid

• rhubarb juicy stalks are edible when cooked and sweetened

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Intoxication and oxidation of ethylene glycol leads to

oxalic acid through a number of intermediates

oxid.COOH

COOH

glyoxalová kyselina

CH2OH

CH2OH

CHO

CHO

COOH

CH2OH

oxid.CHO

CH2OH

COOH

CHO

ethylenglykol glykolaldehyd

glyoxal

glykolová kyselina

št'avelová kyselina

oxid.

oxid.

oxid.

oxid.

ethylene glycol

glycolic acid

glycolaldehyde glyoxylic acid(glyoxylate)

oxalic acid(oxalate)

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Q. 12

30

Some food components conduce to urolithiasis

Food Commentary

Meat (excess)

Milk products

Mineral waters

Spinach

Rhubarb

Vitamin C (excess)

cystein catabolized to SO42- + 2H+ urine acidification

rich in Ca2+ and phosphates

some of them are rich in Ca2+ and Mg2+

contains oxalic acid (up to 1 %)

contains oxalic acid (up to 1 %)

catabolized to oxalic acid

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SubstancePlasma concentration (mmol/l)

Urine excretion (mmol/d)

Na+ 133 - 150 100 - 260

K+ 3.8 - 5.5 40 - 90

Ca2+ 2.0 - 2.7 1 - 6

Mg2+ 0.6 - 1.0 1 - 12

HCO3- 21 - 27 1 - 2

Cl- 97 - 108 120 - 260

H2PO4- + HPO4

2- 0.7 - 1.5 10 - 30

SO42- 0.2 - 0.5 8 - 35

Urea 2 - 8 330 - 600

Uric acid 200 - 420 μmol/l 2 - 3

NH4+ 5 - 50 μmol/l 30 - 50

α-Amino nitrogen 2 - 4 4 - 14

Creatinine 50 - 125 μmol/l 9 - 16

Total proteins 65 - 85 g/l < 150 mg/d