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
Excretion & Elimination: ( major function)
removal of organic wastes products from body fluids (urea, creatinine, uric acid)
2. Homeostatic regulation:
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
Nephron structure
A) Glomerulus
B) Glomerular Capsule
C) Renal Tubule
proximal convoluted tubule
loop of Henle
distal convoluted tubule
D)  Collecting Duct

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
Filtration process occurs in glomulus: lareg mwt compunds as protein and RBCs can’t pass through the glomulus membrane so it reterun back to blood, the filtrate is collectd in Bowmans space and transferred to tubule where the reabsoprtion process occurs in.

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

8. Kidney structure 2- System of tubules
Re-absorption of water and important particales occurs on these tubules
This filtration process is much like the making of espresso or cappuccino. In a cappuccino machine, water is forced under pressure through a fine sieve containing ground coffee; the filtrate is the brewed coffee. The arrangement of the glomerular capillaries in series with the peritubular capillaries is important to maintain a constant pressure in the glomerular capillaries, and thus a constant rate of filtration, despite momentary fluctuations in blood pressure. Once the filtrate has entered the Bowman's capsule, it flows through the lumen of the nephron into the proximal tubule.

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. Renal Function TESTS Blood Tests Urine Tests Urea or BUN.
Creatinine.
uric acid.
levels of several elements : Na+, K+, Cl-, Ca2+, Mg2+, H2CO3 and phosphorus
glomerular filtration rate (GFR)
urine volume
urine urea
minerals in urine
urine protein
urine glucose
hematuria
Osmolality
I shall review the tests in the left column today. The measurement of urine protein is important in certain conditions, e.g.diabetes. The detection of substances such as red cells or glucose could be an early indicator of renal damage.

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

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 or Blood Urea nitrogen test (BUN):
 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

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. Uric acid:
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. Experiment: Measuring serum urea (BUN) level
Principle:
Urea + H2O NH3+ CO2
NH3 + Salicylate + hypochlorite ,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:

21. Calculations
Abs of Bilirubinequavelant

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