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The kidney's primary function is to remove unwanted substances from the blood and excretes them
through the formation of urine. In other words, three of the most important processes which occur
in the formation of urine are glomerular filtration, reabsorption, & secretion. These processes will
make sure that the body is only removed of waste and additional water. Nephrons, the building
blocks of the kidney, each have a glomerulus, which is where blood is filtered. This is because of the
cup-shaped glomerulus, which is a network of capillaries. The glomerulus is also known as the
Bowman's capsule, through which the blood flows because the blood pressure forces water and
other solutes from the capillaries past a filtering membrane and into the capsule. As a result, the
process of producing urine will begin with glomerular filtration. Furthermore, blood pressure inside
the glomerulus forced fluid from capillaries into the glomerular capsule through a cell layer. This is
due to the layer's filtration barrier, which permits the passage of water and small molecules but
blocks the passage of blood cells and large molecules including proteins. As a result, the glomerulus
filters will remove tiny molecules and water from the circulation. The filtrate that is produced will
include waste as well as other substances that the body needs, such as glucose, vital ions, amino
acids, and smaller proteins. Additionally, the filtrate will enter the renal tubule after leaving the
glomerulus. The required material and water are reabsorbed through the renal tubule's tube wall
and into nearby capillaries as the filtrate travels through it. This is due to the fact that only during the
second stage of urine production it will absorb the necessary substances from the filtrate.
The kidneys' renal tubules are where nutrients and water are reabsorbed into the capillaries. As a
result, only water ions and hydrogen will flow through the renal tubes from the capillaries. Because
the filtrate and the released ions when combined to form urine, this process is known as a secretion.
This further implies that urine passes through the nephron tube into the collecting duct, leaves the
kidney through the renal pelvis, enters the ureter, and travels to the bladder. (Body, 2023)
Therefore, this will refer to osmoregulation, which is the process of balancing the amounts of salt
and water. Osmoregulation is crucial because the concentrations of water and salt in the blood can
change. This suggests controlling these concentrations and maintaining the same amounts both
inside and outside of cells to prevent the passage or entry of too much water. The hypothalamus will
not alert the pituitary gland if the water level is determined to be too high. This implies that less ADH
will be secreted, meaning that less water will be reabsorbed by the tubules in the kidney. Since the
,kidney controls and regulates the level of water which means that it reabsorbs a small amount of
water from the filtrate and allows it back into the bloodstream. This indicates that the regulations are
important in order to make sure the body retains sufficient water. Therefore, the body retains
enough water level in the body, which means the kidney reabsorbs water from the filtrate and
produces concentrated urine. Thus, the urine becomes dilute because the kidneys excrete additional
fluid when the body needs to get rid of excess fluid. Moreover, a balance of inorganic ions including
calcium, phosphate, sodium, and potassium, are maintained as well by the body. This is important
because the body’s need to maintain a balanced sodium concentration; the kidney also helps to
remove any additional inorganic ions such as sodium ions from the body in the urine. Similarly, the
body reabsorbs sodium ions from the filtrate in order to keep a balanced level of sodium ions in the
body, if the sodium concentration is low. Consequently, there are organic solutes such as glucose,
amino acids, and urea which are found in the filtrate and will be reabsorbed by the kidney and back
into the bloodstream. On the other hand, waste and urea will be removed from the body in the
urine.
Why urinalysis is often the first tes used in diagnosis
Urinalysis is usually the first test that is used in the diagnosis and treatments of diseases because it
can be able to analyse and determine colour, concentration and odour of urine as it helps to identify
a wide range of illnesses. This is because urinary analysis provides information about an individual's
health as well as diagnosing different numbers of illnesses. As a result, the first step for the urinalysis
test is that the colour of the urine will be examined because it can provide ideas and information
about an individual's health. For example, dark yellow urine could indicate that the individual is
dehydrated or inflamed, whereas light yellow urine indicates that the individual is hydrated.
Additionally, a dark or blood in the urine could also indicate urinary tract infection or inflammation,
meaning that the colour can help in identifying the disease but further examination is required to
prevent obtaining wrong results. Thus, the presence of any bacteria or white blood cell in the urine
further suggests kidney failure or infection. Moreover, the urinalysis test helps to evaluate and
analyse the odour as well as the purity of the urine. This is done because strong or unusual odour
could be used to detect and identify whether an individual is taking any medication or metabolic
problems. As an illustration, a strong odour suggests diabetes, whereas unusually odour could be a
sign of urinary tract infection (UTI). Additionally, the urine's quality is crucial since a clear or cloudy
urine sample might reveal the presence of cells or substances that can point to kidney issues. The
PH, specific gravity, glucose, protein, ketones, and other substances, are components of the urine
which help to detect and demonstrate the urine acidity and alkalinity, meaning that it helps diagnose
and understand the disease. Hence, the urinalysis test is essential to perform because it can identify
and determine the presence of substance in the urine and whether these components are within the
normal range. The presence of red and white blood, germs, cast, crystal, and other substances in the
urine could indicate different diseases and conditions such as: kidney disease, inflammation of the
kidneys, kidney stones, and urinary tract infections. This further suggests that if there is an abnormal
amount of each component in the urine, it could have a huge health complication and further
examination and diagnostic test is required.
Since the urine tests are an easy and quick process to identify and diagnose because they
provide essential health information. This suggests that any disease may be quickly identified,
treated, and evaluated based on the colour, content, and substance of the urine. Thus, more
diagnosing techniques are required in order to obtain accurate results. (Mayoclinic.org, 2021)
, COMPONENTS NORMAL RANGE ABNORMAL RANGE SIGNIFICANCE
Chemical characteristic
Colour Pale yellow Red, brown, dark Dehydration, pseudomonas infections, UTI
Deep amber colour orange colour
Odour Faint aromatic Strong odour Urinary tract infections, metabolic disorder, liver
disease or medication
Water 91-96% Less than 91% or more dehydration or overhydration
than 96%
Protein 150mg/day Presence of protein in Kidney damage, urinary tract infections, diabetes,
urine hypertension, glomerulonephritis or certain
medication
Nitrite Negative Positive Urinary tract infections, bacteria infection
Glucose None Presence of glucose in Diabetes mellitus, low renal threshold for glucose
urine reabsorption
Ketones None Present Altered carbohydrate and fat metabolism in
diabetes mellitus and starvation, dehydration,
vomiting, diarrhoea
Bilirubin Negative Positive Hepatitis, cirrhosis or medications
PH level Normal PH level is 8.0 or higher Acidic or alkaline urine pH may indicate urinary
4.0 - 8.0 tract infections, diabetic ketoacidosis respiratory or
metabolic acidosis, certain medication
Urobilinogen 0.2 - 1.0 mg/dL Higher than 1.0 mg/dL Liver diseases, hemolytic anaemia, biliary
obstruction, hepatitis or medication
Inorganic ions
Sodium 20 mmol/L Higher than 50 Dysfunction, hormonal imbalance, Addison’s
mmol/L disease, Cushing’s syndrome, heart failure or
medication
Potassium 3.6 - 5.2mmol/L Higher than 6.0 Kidney disorders, hormonal imbalance Addision’s
mmol/L disease, cushing’s syndrome or medication
Chloride 98 -107 mEq/L Higher than 107 Kidney dysfunction, dehydration, vomiting,
mEq/L diarrhoea, Addison’s disease, Cushing’s syndrome
or medication
Organic solutes
Urea 7 -20 mg/dL Higher than 60 mg/dL Kidney dysfunction dehydration, urinary tract
infection, kidney disease, urinary obstruction,
muscle disorder or medication
