The role of chemical pathology in the diagnosis, management and prevention of kidney diseases by Oduola Ganiyah (MLS) et al.

1. THE ROLE OF CHEMICAL
PATHOLOGY IN THE
DIAGNOSIS, MANAGEMENT,
PREVENTION OF KIDNEY
DISEASES
DEPARTMENT OF CHEMICAL PATHOLOGY.
FMC, ABEOKUTA
Presenters - Mrs Oduola Ganiyah
Mr Dalyop
Mr Adegoke

2. OUTLINE
• INTRODUCTION
• RENAL ANATOMY
• RENAL PHYSIOLOGY
• URINE FORMATION
• KIDNEY DISESASES
• DIAGNOSIS OF KIDNEY DISEASES
• URINALYSIS / URINE PROTEIN
• CALCULATION OF FRACTIONAL EXCRETION OF SODIUM
• MANAGEMENT AND PREVENTION OF KIDNEY DISEASE
CONT’D

3. INTRODUCTION
• The renal system consists of the kidney,
ureters and urethras. The overall function of
the system filters approximately 200litres of
fluid a day from renal blood flow which
allows for toxins, metabolic waste products
and excess ions to be excreted while keeping
essential substances in the blood.

4. RENALANATOMY
• The kidneys are a pair of bean-shaped organs
found in the lower back region found in the
intestines. The are 7-10cm long and are the
major excretory and osmoregulatory organs.
Along with the ureter, bladder and the
urethra, they make up the urinary system.

5. Diagram Of The Internal Structure
Of The Kidney

6. Internal Structure of the Kidney
• CORTEX: The outer region.it has more uneven
texture than the medulla. The renal capsule,
proximal convoluted tubule and distal convoluted
tubule of the nephron are located here.
• MEDULLA: The inner region consisting of zones
known as pyramids which surround the pelvis.
• PELVIS: The central cavity. Urine formed after blood
is cleansed is deposited here. This cavity is
continuous with the ureter so the urine goes
directly to the bladder.

7. NEPHRON
• The nephron is the functional unit found within
the kidney. Each nephron has the following
structures:
• Bowman’s capsule
• Proximal convoluted tubule
• Distal convoluted tubule
• Loop of henle
• Collecting duct.
• The bowman’s capsule consistsof glomerulus,
afferent arterioles,efferent arterioles,malphigian
body.

8. A Diagram Of The Nephron

9. RENAL PHYSIOLOGY
• This is the study of the physiology of the kidney.
The kidney filter unwanted substances from the
blood and produce urine to excrete them. Some of
the other functions of the kidney are:
• It regulates plasma osmolarity by modulating the
amount of water, solutes and electrolyes in the
blood.
• It ensures long term acid-base balance and also
produces erythropoietin which stimulates the
production of red blood cells.

10. • It also produces renin for blood pressure
regulation and carries out theconversion of
vitamin D to its active form.
• The kidney also excretes metabolic waste
products and foreign substances.
• There are three main steps of urine formation:
• Glomerular filtration
• Reabsorption
• Secretion
• These processes ensure that only waste and
excess water are removed from the body.

11. Kidney Diseases
• GLOMERULONEPHRITIS
• This is an autoimmune injury of the glomeruli of
both kidneys.
• NEPHROTIC SYNDROME
• It refers to a serious increase in the permeability
of the glomeruli barrier to albumin,resulting in a
marked loss of albumin in the urine. The
albuminuria(>3g per day) causes
hypoalbuminaemia and generalized oedema.

12. Kidney Diseases
• RENAL FAILURE
• This is classified as either acute or chronic.
• Acute Renal Failure occurs suddenly,often
secondary to sudden illness or therapy. Acute
renal failure is characterized by loss of sodium in
blood and increased fraction of sodium in
urine,especially when compared to creatinine
clearance. Loss of sodium is due primarily to
decreased tubular function,which helps regulate
sodium and other electrolyte levels.

13. • Chronic Renal Failure
• This occurs over a longer period of time, with renal
insufficiency progressing through several clear-cut
stages.
• Chronic renal failure may also be is secondary to an
underlying illness. It is often caused by chronic
illness with complications that affects the kidney
such as the immunological damage of systemic
lupus erythematous or the non-immunological
damage of diabetic nephropathy or multiple
myeloma.

14. Diagnosis Of Kidney Disease
• The chemical pathology laboratory provides
the patient’s Urinalysis, Urine and plasma
protein, Urea, Creatinine and Electrolytes
result, which are used in determining:
• A particular kidney disease
• Staging of the kidney disease
• Monitoring treatment progress

15. Laboratory Diagnosis of Kidney
Disease
The chemical pathology lab provides the
patient's Urinalysis, Urine protein, Urea,
Creatinine and Electrolytes result, which are
used in determining:
A particular kidney disease,
Staging of the kidney disease,
Monitoring treatment progress

16. Urine Test
Urinalysis
Dipstick: proteinuria 3–4+
Microalbumin Test
Result generally indicate
<30mg of protein is normal
30- 300mg protein is known as microalbuminuria and it may indicate early
kidney disease.
>300 mg of protein is known as macroalbuminuria and it indicates more
advanced kidney disease.
Spot Protein: Creatinine Ratio
Calculated as: Urine protein/ Urine creatinine
>0.2 g/mmol is an indication of nephrotic syndrome.
24hours urinary protein
Calculated as (Estimated protein/ 100) * volume of urine

17. Plasma Urea / Creatinine
• The reference range for the Urea-to-creatinine ratio
is 10:1 to 20:1. Increases in the ratio may be caused
by prerenal, renal, and postrenal factors.
• Prerenal changes include variation of protein intake
and dehydration.
• Renal disorders that affect the Urea-to-creatinine
ratio include renal failure and glomerular damage.
• Postrenal changes that affect this ratio include
urinary tract infections.

19. CALCULATION OF
FRACTIONAL EXCRETION OF
SODIUM
Fractional excretion of sodium is defined as the fraction
of sodium actually excreted by the body relative to the
amount filtered by the kidney. FENa is not a test, but
rather a calculation based on the concentrations of
sodium and creatinine in blood and urine.
• FENa = urine Na/plasma Na x plasma Cr/urine Cr
x100%
• FENa of less than 1% indicates decreased blood flow
to the kidney, while FENa of greater than 1% (and
usually greater than 3%) suggests kidney damaged.

20. Creatinine Clearance Test
Creatinine clearance measures the ability of the glomerulus to filter
chemicals from the blood. The best substance to use for glomerular
clearance would be a chemical that is filtered completely through the
glomerulus and not reabsorbed through the nephron tubule.
Creatinine meets the criterion for clearance and is also an endogenous
substance; that is, it is produced in the body. Other substances, such as
inulin, may be used for evaluation of creatinine clearance; however,
they are exogenous substances and must be introduced into the body.
Creatinine clearance is measured as a rate; therefore, the test must be
timed. The test measures the movement of the substance from blood
to urine; therefore, both blood and urine concentrations of the
chemical must be measured.

21. Creatinine Clearance cont’d.
• Creatinine clearance = (Urine Creatinine (mg/dl) x Urine Volume) x average surface area (m2)
(Plasma Creatinine (mg/dl) x Time (min) x patient surface area (m2)
Where average surface area is 1.73m2
• Shwartz Formula is used to calculate creatinine clearance of pediatrics
Creatinine clearance = (k x Ht) Creatinine
Where k = 0.45, if age < 1 year,
k = 0.55, if age = 1 -12 years
Ht = Height in cm
Reference range
Male (95-130mL/min) Female (80-120mL/min)

22. Glomerular Filtration Rate Test
• A GFR test is used to describe the flow rate of
filtered fluid through the kidney. It differs from
creatinine clearance rate which measures the
volume of blood (plasma) cleared of
creatinine per unit time, even though it is a
useful measure for approximating the GFR.
• Creatinine clearance exceeds GFR due to
creatinine secretion by the renal tubules.

23. GFR cont’d.
• GFR = (Urine Creatinine x Urine volume per unit
time)/ Plasma Creatinine
• Estimated GFR (eGFR) is now recommended by
clinical practice guidelines and regulatory
agencies for routine evaluation of GFR.
In men,
Creatinine clearance (eGFR) = [(140 – age(years) x weight (kg)]
72 x plasma creatinine (µmol/L)
In women,
Creatinine clearance (eGFR)) = [(140 – age(years) x weight (kg)] x 0.85
72 x plasma creatinine (µmol/L)

24. Clinical interpretation of GFR results

25. Anion gap
• The anion gap is a calculation of the difference between
anions and cations in blood. The gap represents chemical
anions other than those used in the formulas (sodium,
potassium, chloride, and bicarbonate) that might be present
in blood. The gap is used to estimate acid-base and
electrolyte disturbances.
• There are two commonly used formulas for calculation of
the anion gap, with or without the inclusion of potassium
ions.

26. Anion gap cont’d
• The most commonly used formula is:
(Na+K) – (Cl+HCO3)
• The formula (Na) – (Cl+HCO3) can be used but is generally being
replaced by the formula that includes potassium. The reference range is
slightly different if both cations are included in the calculation (10 to 20
mmol/L), while it is 7 to 16 mmol/L if the calculation does not include
potassium.

27. Anion gap cont’d
• The anion gap represents those unmeasured anions that are
present in body fluids providing electrolyte balance and
neutrality, such as lactate, sulfates, phosphates, ketones,
organic acids, and ionized proteins.
• For example, in many types of metabolic acidosis, the anion
gap is typically increased due to a deficit of bicarbonate ions
and the presence of organic acids.
• A decreased anion gap may be due to situations that decrease
sodium relative to an excess of chloride and bicarbonate.

28. MANAGEMENT AND
PREVENTION OF KIDNEY
DISEASE
• Management is focus to slow or control the cause of your
kidney disease.
• Treatment options vary depending on the cause.but kidney
damage can continue to worsen even when an underlying
condition such as diabetes mellitus or high blood pressure
has been controlled.
Management plan includes:
High blood pressure medications.
People with kidney diseases can have worsening high blood
pressure. A drug to lower your blood pressure is recommended
commonly angiotensin converting enzymes(ACE) inhibitors or
angiotensin II receptors blockers.

29. Management and prevention of
kidney disease cont’d
Medications to relieve swelling.
People with chronic kidney disease often retain fluids.
This can lead to swelling in the legs as well as high
blood pressure.
Medications called diuretics can help maintain the
balance of fluids in your body
Medication to lower cholesterol levels
People with chronic kidney disease often have high
level of bad cholesterol which can increase the risk of
heart disease. Medications called statins are
recommended to lower your cholesterol.

30. Management and prevention of kidney
disease cont’d
• Treatment for end- stage kidney disease
• If your kidneys can’t keep up with waste and fluid
clearance on their own and you develop complete or near
complete kidney failure, you have “ end- stage renal
disease” (ESRD) at that point you need dialysis.
• Dialysis artificially removes waste products and extra fluid
from your blood when your kidneys can no longer do this.
• In hemodialysis,a machine filters waste and excess fluids
from your blood
• In peritoneal dialysis,a thin tube inserted into your
abdomen cavity with a dialysis solution that absorbs
waste and excess fluids. After a time ,the dialysis solution
drains from your body, carrying the waste with it.

31. Management and prevention of kidney
disease cont’d
• Kidney transplant
• A kidney transplant involves surgically placing
a healthy kidney from a donor into your
body.
• Transplanted kidneys can come from
deceased or living donors.

32. Management and prevention of kidney
disease cont’d
• Lifestyle remedies
• Make a healthy food choices
• Make physical activity part of your routine.
• Aim for a healthy weight
• Get regular check ups.