1. Abnormal composition of urine

2. Urine examination Physical – volume, density, colour, odour, turbidity
Chemical
Examination of urine sediment

3. Chemical examination of urine
Routine: pH
proteins
ketone bodies
glucose
blood in the urine
nitrites
leukocytes
Targeted:
bilirubin, urobilinogen
amino acid metabolites
hormones (cortisol, sex hormones, somatotropin)

4. pH of urine Usual range: 5,5 – 7,0 (maximal range: 4,5 – 7,5)
Aciduria – pH < 5,4
Cause:
diet high in meat products (sulphur and phosphorus are metabolized to sulphates and phosphates)
compensation of metabolic / respiratory acidosis
along with ketonuria can be predictive of starving/lack of saccha-rides; if glucosuria is also present, the combination can indicate decompensated DM
Alkaluria (alkalinuria) – pH > 6,5
lacto vegetarian diet
urinary tract infection (bacterial urease)
compensation of respiratory / metabolic alkalosis at its onset

5. Proteins in urine
Proteinuria = excessive excretion of proteins into the urine: >150 mg/d
Cause:
physiological: physical effort
pathological:
renal disease – according to the origin:
glomerular proteinuria
tubular proteinuria
glomerular and tubular proteinuria
post-renal proteinuria – either bleeding into the urinary tract, or local secretion of immunoglobulin
pre-renal proteinuria – due to an increased plasma concentration of low-molecular proteins ( increased excretion into the urine)

6. Ketone bodies Acetone, acetoacetate, -hydroxybutyrate
Synthesis: from acetyl-CoA, produced by -oxidation of fatty acids
Starvation, physical effort, stress   lipolysis and -oxidation of FA; acetyl-CoA is used preferentially for the synthesis of ketone bodies

7. Ketonuria  level of ketone bodies in the urine (normally – very low)
Causes:
severe DM
long-term starvation, marked reduction of saccharides in diet
tenacious vomiting
Test strips: acetoacetate (not -HB!) reacts with nitroprusside (in the presence of alkali), producing purple-coloured complexes (Legal reaction)

8. Glucose in urine Physiological range: 0,1 – 1,4 mmol/l
Test strips: glucose is oxidized by glucose oxidase; H2O2 is formed that converts a colourless substrate to a coloured complex
Glucosuria (glycosuria) = increased amount of glucose in the urine; causes:
hyperglycaemia > 10 mmol/l (DM, acute pancreatitis…)
renal glycosuria (glucose is abnormally excreted by the kidney)
increased intestinal reabsorption

9. Blood in urine A) hematuria (erythrocyturia) – causes:
renal disease (glomerulonephritis, tumours)
other diseases of the urinary tract
haemorrhagic diathesis (e.g. thrombocytopathy,haemophilia)
B) hemoglobinuria – excessive intravascular haemolysis (haemolytic anaemia, e.g. hereditary or after non-compatible transfusion)
Test:
i) test strip detecting hemoglobin: Hb catalyzes oxidation of the substrate with peroxide to a coloured product (pseudoperoxidase activity)
ii) erythrocytes in the urinary sediment

10. Nitrites in urine
Nitrates in the urine can by reduced by some pathogenic bacteria to nitrites that can thus serve as indicators of the infection in the urinary tract
These bacteria include: E. Coli, Klebsiella, Salmonella, Proteus, Aerobacter, Citrobacter, some strains of Enterococcus, Staphylococcus, Pseudomonas

11. Leukocytes in urine
Increased amount of leukocytes (> 20/µl) – pyuria – is a sign of inflammation in the urinary tract
Test: granulocyte esterase activity
Causes:
infection of the urinary tract
tumours

12. Urobilinogen and bilirubin in urine
heme → biliverdin → bilirubin
transport to the liver (albumin)
conjugation with glucuronate  bilirubin diglucuronide
secreted into the bile
bacteria in the small intestine release bilirubin from diglucuronide and convert it to colourless urobilinogens
a small fraction is excreted into the urine by the kidney
most of them are oxidi-zed to pigments and excreted in the faeces (urobilin, stercobilin)
a small fraction is reabsorbed and re-excreted through the liver into the bile

13. Causes of icterus
Icterus (jaundice): bilirubin in the blood exceeds 10 mg/l (hyperbilirubine-mia)  bilirubin diffuses into tissues, which become yellow
Pre-hepatic: haemolysis  overproduction of bilirubin that exceeds the liver's capacity for handling bilirubin (haemolytic anaemia, neonatal jaundice)  unconjugated bilirubin in blood and urobilinogen in urine
Hepatic: liver damage (hepatitis, cirrhosis)   capacity for handling bilirubin (uptake, conjugation, excretion)   conj. as well as unconj. bilirubin in blood, urobilinogen in urine can  if microobstruction is present, otherwise it rises (impaired enterohepatic cycle)
Post-hepatic – obstructive: obstruction of the biliary tree (concretions, tumours)  conj. birubin regurgitates into the hepatic veins and lymphatics   conj. bilirubin in blood, no urobilinogen in urine

14. Urobilinogen in urine Abnormal values: ≥ 10 mg/l Causes:
increased degradation of hemoglobin (heavy bleeding, haemolytic jaundice)
liver disease interfering with the enterohepatic urobilinogen cycle (hepatitis, tumours)
Causes of the absence of urobilinogen in the urine:
obstruction in the biliary tree
failure of bile production in the liver
absence of intestinal flora

15. Direct and indirect bilirubin
Conjugated bilirubin = direct bilirubin x unconjugated = indirect
Normally, only conjugated bilirubin can appear in the urine  the level is increased when the plasma concentration of conjugated bilirubin rises
On the other hand, only unconjugated bilirubin can cross BBB (neonatal jaundice  encephalopathy can occur)

16. Bilirubin in blood and urine
 conj. bilirubin in blood  bilirubin is in the urine:
liver damage, microobstruction (hepatitis, cirrhosis)
Dubin-Johnson Syndrome: defect in the hepatic secretion of conjugated bilirubin into the bile
obstructive jaundice
 unconj. bilirubin in blood  bilirubin is NOT in the urine:
hemolytic anaemia
neonatal jaundice: accelerated haemolysis and immature hepatic system for bilirubin metabolism (low activity of UDP-glucuronosyltransferase)
Crigler-Najjar Syndrome: decreased activity of bilirubin UDP-glucuronosyltransferase

17. Clinical parameters in 3 different causes of jaundice
condition
serum bilirubin
urine urobilinogen
urine bilirubin
fecal urobilinogen
normal
direct: 0,1-0,4 mg/dl
indirect: 0,2-0,7 mg/dl
0-4 mg/24h
absent
mg/24h
haemolytic anaemia
 indirect 
hepatitis
 direct and indirect
 if micro-obstruction is present
present if mic-ro-obstruction occurs 
obstructive jaundice
 direct
present
trace to absent

18. Phenylketonuria
Defect in phenylalanine hydroxylase  Phe cannot be converted to Tyr, accumulates, and is metabolized to phenylacetate, phenyllactate, and phenylacetylglutamine. Urinary level of phenylpyruvate is elevated.
If left untreated, it leads to mental retardation
Prevention: low-Phe diet
Screening: plasma Phe → genetic test

19. Urolithiasis
Urinary calculi (concretions) are formed in the urinary tract
80-90% = renal concretions made of calcium salts (oxalate, phosphate)
Factors that predispose to calculi formation:
highly concentrated urine (e.g. dehydration)
increased urinary excretion of:
phosphates, calcium (e.g. increased breakdown of bones)
oxalates
uric acid (hyperuricosuria)
cystine (cystinuria – may be due to impaired resorption in the kidney)
urine alkalization (in case of excretion of Ca2+, phosphates, oxalates)
urine acidification (pH<5,5) in case of excretion of uric acid

20. Hyperuricosuria
Excretion of > mg of uric acid into the urine/24h; serum uric acid rises, too (hyperuricemia)
Causes:
gout
cancer, especially if treated with cytostatic drugs or radiation therapy (increased cell death and thus also increased NA degradation)
renal disease
high intake of purines in the diet
dehydration

21. Revision: purine catabolism

22. Gout
Enzyme defect in PRPP-synthase or HGPRTase  overproduction of purines, and thereby also of uric acid  crystallization of urates in soft tissues and joints  inflammation (arthritis).
Therapy: allopurinol – converted by xanthine oxidase to alloxanthine that inhibits the enzyme   synthesis of uric acid, more soluble xanthine and hypoxanthine are excreted

23. PRPPS and HGPRT in purine metabolism
(first step)
(„salvage pathway“)

24. Urine sediment Urine sediment: substances discharged from organs
crystals (oxalates, urates, phosphates)
Examination detects the presence of:
blood – erythrocyturia (>5 ery/µl); causes: impaired permeability of glomerular membrane, infection, urolithiasis…
leukocytes – pyuria (>10 leuko/µl); causes: infection of the urinary tract
casts – formed in the kidney (the matrix is made of the protein produced by tubules, other components: plasma proteins, lipid droplets)  casts can indicate a renal disease (different types of casts indicate different types of damage)
epithelial cells
microorganisms

25. macrophage
hyaline
cast
erythrocytes
a…granulocyte; b…bacteria

26. hyaline cast
cuboidal epithelial
cell
a…tubular epithelial cell (inside a cast)
b…2 cells of a transitional epithelium

27. granular
cast
waxy cast (with the cells of tubular epithelium inside)

28. fatty cast
granulocyte
yeast
yeast