The document details the functions of the renal system, emphasizing its roles in excretion, homeostasis, and hormone production, specifically outlining the structure and functioning of nephrons. It explains urine formation through glomerular filtration, tubular reabsorption, and secretion, along with various kidney function tests and factors affecting kidney health. Additionally, it addresses the interpretation of biochemical tests related to kidney function, including the implications of abnormal results and the relationship between urea levels and renal dysfunction.

1. Lab (4):
Renal Function test (RFT)
Khadija Balubaid
KAU-Faculty of Science- Biochemistry department
Clinical biochemistry lab (Bioc 416) 2013

2. The Function of Urinary System
1. Excretion & Elimination: ( major function)
removal of organic wastes products from body fluids (urea,
creatinine, uric acid)
2. Homeostatic regulation:
a. Water -Salt Balance(Regulates the body balance in water and
minerals. (sodium, potassium, chloride, calcium and phosphate)
b. Acid - base Balance(Maintains blood volume, pressure and pH.)
3. Endocrine function:
produce hormones (erythropoietin, renin and prostaglandin).

3. An Introduction to the Urinary System
Produces urine
Transports urine
towards bladder
Temporarily store
urine
Conducts urine
to exterior

4. Kidneys Structure
• The functional unit of kidney is Nephrone
• Each kidney contains million nephrone
• Nephrone consists from two major parts:
 Glmulus: Filtration
(it is high pressure mass of capillaries that filter blood)
 System of tubules: re-absorption
System of
tubules
Glmulus

5. Each kidney consists of one million functional
units: Nephrone
A) Glomerulus
B) Glomerular Capsule
C) Renal Tubule
 proximal convoluted tubule
• loop of Henle
• distal convoluted tubule
D) Collecting Duct
Nephron structure

6. 1- Glumular:
• is capsulated with double walled capsule called Boman’s capsule
• Glomular capilary membrane consists of three layers which allows
some partials of blood to pass though but not all, blood cells and
proteins are large and can't pass
• The fluid that filtered and passed through membrane is called
filtrate
• Filtrate is diffused across Bowman’s space to tubules system of
nephrone

7. What gets filtered in the glomerulus
What gets filtered in the glomerulus
?
?
Freely filtared
(filterd = passed)
• H2O
• Elements : (Na+
, K+
,
Cl-
, Mg2+
, PO4
)
• Glucose
• Urea
• Creatinine
• Insulin
Not filtred
(not passed)
• Protein
• Blood cells

8. Kidney structure
• 2- System of tubules
• Re-absorption of water and
important particales occurs on
these tubules

9. Urine Formation
• Urine formation requires :
 Glomerular Filtration
Due to differences in pressure water, small molecules
move from the glomerulus capillaries into the
glomerular capsule
 Tubular reabsorption
many molecules are reabsorbed from the nephron
into the capillary (diffusion, facilitated
diffusion, osmosis, and active transport) i.e.
Glucose is actively reabsorbed with transport
carriers.
If the carriers are inactive glucose appears in the
urine indicating diabetes
 Tubular secretion
Substances are actively removed from blood and
added to tubular fluid (active transport)
ie. H+, creatinine, and some drugs are moved by
active transport from the blood into the distal
convoluted tubule

10.  glomerular filtration rate
(GFR)
 urine volume
 urine urea
 minerals in urine
 urine protein
 urine glucose
 hematuria
 Osmolality
 Urea or BUN.
 Creatinine.
 uric acid.
 levels of several
elements : Na+
, K+
, Cl-
,
Ca2+
, Mg2+
, H2CO3 and
phosphorus

11. Measurement of GFR
 Clearance tests
 Plasma creatinine
 Urea, uric acid and
β2 microglobulinrea
Biochemical Tests of
Renal Function
Renal tubular
function tests
 Osmolality
measurements
 Specific
proteinurea
 Glycouria
 Aminoaciduria
 Urinalysis
 Appearance
 Specific gravity
and osmolality
 pH
 osmolality
 Glucose
 Protein
 Urinary
sediments

12. • Many factors can affect on kidney function leads to kidney
damage;
 Anatomical structure (congenital disease)
 Infections
 Diabetes
 Renal stones
 Smoking
 Diet and water
 Most common causes : Diabetes and high blood pressure
• Kidney damage occurs in stages that can early detected.
• Abnormal results of kidney function tests may be obtained due to a temporary
renal dysfunction.
• Therefore, the test should be performed repeatedly and interpreted on the basis
of a series of results.

13. • Urea is waste product of protein metabolism, it synthesized in
liver via urea cycle then it transported by blood to kidney to be
excreted in urine.
• Blood urea level is sensitive but not specific indicator for renal
dysfunction, because:
 Its level is affected by dietary protein
 Other non renal causes such as heart failure and blood pressure
may effect on its level.
 Its level is elevated in last stages of renal failure after 50% of
renal function is lost.
BUN= 50% urea
BUN= 50% urea

14. High serum urea can indicates:
• Renal insufficiency. (due to obstruction or cancer)
• Urinary tract blockage (by a kidney stone or tumor)
• Heart failure (poor renal perfusion: low blood flow to kidney).
• Dehydration (lack of fluid volume to excrete waste products).
• High-protein diet
• Some medicines.
Low serum urea may be due to:
• Very low protein diet as in malnutrition
• Severe liver damage inhibits urea cycle, decrease urea formation
and increase free ammonia leads to hepatic comma.
• Overhydration.

15. • Is the end product of purine metabolism and excreted in urine.
• Purine in body comes from food and break down of body
cells.
• Elevated level of uric acid in blood is one of the markers of
kidney dysfunction.

16. Gout:
Is disease characterized by high level of uric acid which
deposited in solid form in the joins causing arthritis.

17. High blood uric acid occurs in:
• Gout
• Renal failure (due to decreased excretion in urine)
• Leukemia (increased turnover of cells)
• Alcoholism
• Toxaemia of pregnancy.
• Diabetes Mellitues.
• Starvation.
• Drugs like diuretics.
Low blood uric acid occurs in:
- Liver diseases (cirrhosis)
- Renal disease that decrease renal tubular re-absorption
- Some drugs

18. Principle:
Urea + H2O NH3+ CO2
NH3 + Salicylate + hypochlorite 2,2 dicarboxy indophenol
Urease

19. Kit components
•
Reagents
:
•
Sulfanalic acid reagent
•
Sodium nitrate reagent
•
Methanol reagent
•
Bilirubinequavalent standard (5mg/dl T.bil; 2.5
mg/dl D.bil)
•

20. Procedure
Procedure
:
:

21. C
Calculations
Abs of Bilirubinequavelant

22. BUN: 5-23 mg/dl
Urea: 10-50mg/dl
Normal range