Download Urinary System 3

Urine Chemistry
NORMAL CONSTITUENTS OF URINE
Urine
4%
96%
Inorganic
Water
Organic
2A
2U
2C
2P
Organic nitrogenous part:
It is also called
non protein nitrogenous
constituent = (NPN):
8
1.Urea:
It is the principal end product of
protein metabolism in
mammals.
• 20 - 40 g/d.
•Constitutes 85% of total
urinary nitrogen excretion.
Urea excretion is directly
proportional to protein intake.
Protein – rich Diet
More Urea excretion
Urea excretion is increased
whenever protein catabolism is
increased as in
 fever,
diabetes mellitus or
excess adrenocortical activity.
Urea is synthesized in the liver, so
decreased urea excretion is met with
in advanced liver diseases.
Retention occurs in nephritis which
results in smaller output and increase in
urea concentration in the blood.
2. Ammonia:
 0.8-1.2 g/day in urine.
Its formation and excretion are
important mechanisms that protect
the body against acidosis.
Ammonia is derived from
glutamine by glutaminase enzyme
in the kidney.
f
The formed ammonia drags with it
+
H to be excreted as ammonium ions
+
(NH4 ) which is excreted in the
urine in the form of NH4Cl.
3. Creatinine
Urinary Cr. Excretion  1-1.8 g/day.
It is the metabolic end product of
creatine in muscles
Urinary creatinine is proportional to the
muscle bulk , but regardless to the
amount of protein in diet.
3. Creatinine
3. Creatinine
Creatinine level in blood and its
Excretion in urine is a good index of
kidney functions
(creatinine clearance).
4. Creatine:
• 60-150 mg /day.
Urinary creatine represent 7% of total creatinine
output.

1.
2.
3.
Creatinuria
In pregnancy,
Physiological
infancy - childehood Creatinuria
Athletes
in pathological states such as
 hyperthyroidism, starvation and
impaired carbohydrate metabolism
 in diseases involving loss of muscle
mass (myopathies).
5. Uric acid:
0.8-1.2 g/day.
 The most important end product of
oxidation of purines in the body
 Occurs in urine in the form of
urates.
 It is derived from
1. dietary nucleoproteins
2. breakdown of cellular nucleoproteins.
 Soluble in alkaline urine, but it is
precipitated in acid urine.
 Increase in Urine In
• Leukaemia
• Gout
• severe liver diseases and.
6. Hippuric acid:
 0.7 g/day.
It is formed by conjunction of
benzoic acid with glycine.
Vegetables and fruits contain high
content of benzoic acid.
Also, benzoic acid is derived from
putrefaction of aromatic amino acids
from benzoate of preserved food.
7. Amino acids:
 150-200 mg/day.
Aminoacidurias  ???
Amino acidurias
 Occur in case of extensive destruction of the
liver as in liver poisoning by: chloroform
and tetrachlorocarbon
 Also, inborn error known as (cystinuria)
which is a tubular defect in reabsorption of
cystine, arginine, lysine and ornithine.
8. Purines:
Only traces.
Several purines are found in urine
some of them are derived from the
caffeine and theobormine found
in coffee and tea.
Methyl Xanthines
9. Indican:
 It is a product of tryptophan
putrefaction in gut ,
 normally present in small
amounts
 and increases in constipation
Organic non-nitrogenous part:
1- Oxalic acid
 whose amount is very low.
 It is found as calcium oxalate crystals in
urinary deposits
 It is increased after ingestion of fruits and
vegetables of high oxalate content,
 is increased in inherited metabolic disease
(primary hyperoxaluria) large amount of
oxalates may be continuously excreted.
2- Organic acids: These include citric
acid, lactic acid and glucuronic acid.
Urinary Inorganic
constituents
1. Chlorides:
9-16g/day.
Next to urea, chlorides are the
most abundant substances in
urine
Mainly excreted as sodium
chloride.
Its output depends upon its intake
2. Sulfates:
2-3 g/day.
 These are derived mainly from sulfur
containing amino acids of proteins.
 Urinary sulfates can be divided into 3
forms:
a) Inorganic sulfates (85%): is
proportional to the output of the total
nitrogen since both originate from protein
metabolism.
b) Ethereal sulfates (10%):
 Are esters of sulfuric acid with certain
phenols
 (e.g. indoxyl, indican, and other sulfur
conjuguates formed in detoxication).
c) Neutral sulfates (5%): This represents the
unoxidized sulfur.
3. Phosphates:
2-3 g/day.
Relative proportions of NaH2PO4
determines the pH of urine.
It is largely derived from the
ingested food, which contains
inorganic & organic phosphate (e.g.
nucleoproteins, phosphoproteins..etc).
Increases Phosphate level in
hyperparathyroidism
osteomalacia.
Decrease sometimes occurs in
 renal diseases and
infectious diseases
hypoparathyroidism.
4. Cations:
Sodium, Potassium,
calcium, and magnesium
are the 4 cations of the
extracellular fluids present in
urine.
ABNORMAL CONSTITUENTS
OF URINE
 Proteis
 Sugars
 Ketone Bodies
 Bile
 Blood
 Pophyrins
a) Proteins (proteinuria):
1.
2.
Physiological (less than 500 mg/day) after severe
muscle excercise, after prolonged standing, after a
high protein meal and during pregnancy.
Pathological:
 Prerenal: The primary causes are factors
operating before the kidney, e.g. heart failure.
 Renal: The lesion is intrinsic in the kidney, e.g.
nephritis and nephrosis.
 Postrenal: The lesion is in the lower urinary tract,
e.g. cystitis.
The increased amount of albumin in urine called
albuminuria,
 Microalbuminuria if  30-300 mg/day
 Macroalbuminuria  if more > 300mg /day
• Albumin in urine is detected by
 heat coagulation test.
• There are other types of protein which may
appear in urine as Bence-Jones Proteins.
Bence-Jones proteins:
 These are abnormal globulins that appear
mainly in multiple myeloma which is a
bone marrow cancer, also in leukemia and
lymphosarcoma.
 in such conditions, urine undergo 3 phases:
1. clotting when heated to 60°C,
2. undergoes redissolving at 100°C and
3. reclotting by cooling.
The renal threshold for glucose is 180 mg/dl
b) Sugar:
Glucose (glucosuria): Normally not more than
1 g/day (many types of glucosuria).
Fructose (fructosuria): It is a rare anomaly in
which the metabolism of fructose is disturbed.
(Deficient Fructokinase)
Galaclose (galactosuria): May occasionally
occur in infants and mothers, also in
congenital galactosemia.
Glucosuria
A- Hyperglycemic glucosuria:
It occurs when the blood glucose level exceeds the
renal threshold (180 mg/ dl). It is caused by:
 1- Diabetes mellitus.
 2- Epinephrine glucosuria: as emotional or stress glucosuria or in
case of pheochromocytoma
 3- Alimentary glucosuria: It is due to increased rate of glucose
absorption as in cases of gastrectomy or gastrojejunostomy.
B- Normoglycemic or renal glucosuria: In these cases, the blood
glucose is within normal range.
 1- Congenital renal glucosuria (benign glucosuria or diabetes
innocens), due to congenital defects in renal tubular mechanism
for reabsorption of glucose.
 2- Acquired renal diseases as in nephritis.
Lactose (lactosuria): During
pregnancy and lactation, may appear
in mothers and infants.
Pentose (pentosuria):
 May occur after ingestion of food
containing large amounts of pentoses.
 Also appears in congenital pentosuria
due to inability to metabolise LXylulose.
c) Ketone bodies (ketonuria):
 They are acetone, aceto-acetate, & 3hydroxybutyrate.
 Normally 3-15 mg are excreted in urine per day.
 Ketonuria is the presence of excessive amounts
of ketone bodies in urine.
 This may occur in uncontrolled
diabetes mellitus and during prolonged
starvation.
 Aceto-acetate and 3-hydroxybutyrate are
eleminated as salts thus depleting the alkali
reserve which results in acidosis.
d) Bile:
Bile pigments: They appear
in urine, in hepatic, obstructive
and haemolytic jaundice.
Bile salts: Bile salts appear
only in obstructive jaundice.
e) Blood (haematuria):
Due to
 Bilharziasis,
Blood diseases,
Renal stones
Renal tumours
Haemoglobinuria
f) Porphyrin:
The occurrance of uroporphyrins
as well as increased amount
of coproporphyrins in urine is
termed porphyria.
(Defect in Haem Synthesizing
Enzymes)