Blood glucose measurement and urinalysis/endocrine
worksheet
Submission dateline: 3pm on 30th April 2021
Submission method: Via Turnitin submission link on
Moodle.
Oral glucose tolerance test
The OGTT evaluates the efficiency of the body to metabolize glucose and has
been regarded as the “gold standard” for diagnosis of diabetes. Diabetes
symptoms do not appear until the pathology has become well established,
sometimes for years. Glycaemia monitoring remains the best method to
detect pre-diabetic states and also make people sensitive to the influence of
their lifestyle (BMI, exercise, foods etc.) on the physiology of their body and
on their health.
The test takes places after an overnight fast (minimum 8 hours). A blood test
is taken before the patient is asked to consume a drink containing 75g
glucose. Samples of blood are collected at regular intervals (such as 30min,
60min, 90min) or at 120min after glucose ingestion. World Health
Organization-defined glucose levels are shown in Table 1.
Table 1. 2006 WHO recommendations for diagnostic criteria for diabetes and
intermediate hyperglycaemia
Normal
Fasting
< 6.1 mmol/L
OGTT (2h)
< 7.8 mmol/L
Impaired
glucose
tolerance
< 7.0 mmol/L
≥ 7.8 and
< 11.1 mmol/L
Diabetes
mellitus
≥ 7.0 mmol/L
≥ 11.1mmol/L
Absorption of a meal rich in carbohydrate (such as in the OGTT) acutely
elevate the blood glucose level, and we rely on control systems to monitor
such changes and make appropriate adjustments, maintain blood glucose
within a relatively narrow range (4 – 8mmol/L).
1. Describe how blood glucose is controlled - which hormones are involved,
what processes do they regulate? (300 words)
In the absorptive (fed) state, glucose from absorbed nutrients is either used
as energy for most cells, while the excess is converted to glycogen and
stored in the liver and muscle or glycerol to triglycerides and stored in
adipose tissue. This process is anabolic and is governed by the hormone
insulin that is released by B cells in the pancreas. Insulin is released to lower
BG levels upon intake of food and is monitored by somatostatin. It does so
by increasing uptake of glucose via GLUT-4, storage of glucose as glycogen,
uptake of amino acids and synthesis of protein and DNA synthesis. On the
other hand, in a starved state, a cells in the pancreas release glucagon upon
low BG and is inhibited by high BG, insulin and somatostatin. Unlike insulin,
it stimulates hepatic glycogenolysis and glycolysis which refers to breakdown
of glycogen in the liver and muscle and other cells to glucose respectively. It
also stimulates gluconeogenesis which ameans formation of glucose from
non carb precursors and lipolysis that converts triglycerides from adipose
tissue to glycerol and then glucose. Glucagon and insulin work together
automatically as a negative feedback system to keeps BG levels stable.
Foods will have different effects on blood glucose both due to the body's
state of health and the composition of the food. Glycaemic index (GI) is a
measure of how rapidly the carbohydrates in a food lead to an elevation in
blood glucose; a food with a high GI (such as chocolate, biscuits) raises
blood glucose more than a food with a medium or low GI (wholemeal bread,
beans). Glycaemic load (GL) relates to the overall effect a food has on blood
sugar, the total amount of digestible carbohydrates in a food.
In a study to examine the effects of glycaemic load on postprandial blood
glucose, the following data were obtained: Table 2 shows the summary data
for each of the “treatments” in normal healthy subjects (aged 20-25 years).
Included also is the OGTT of a normal healthy subject and that of a patient
with diabetes mellitus in which an OGTT was performed in the diagnosis of
her condition.
Table 2. Mean blood glucose (mmol/L) for treatment GL groups (n=8),
sampling following an overnight fast and at intervals after ingestion of a
“meal”
OGTT, normal
OGTT, diabetes
HGL
MGL
LGL
Fasted
4.4
7.2
30 min
7.6
10.8
60 min
8.4
13.4
120 min
6.2
12.8
4.6
4.4
4.5
8.1
6.3
5.2
7.3
6.2
4.8
6.3
5.5
4.5
Treatments groups:
OGTT
75g glucose in 250mL water (75g CHO, 300 Kcal)
HGL (high GL)
Energy drink and pop tart (102g CHO, 521 Kcal)
MGL (medium GL) Bagel, peanut butter, banana (89g CHO, 565 Kcal)
LGL (low GL)
Ham, cheese (12g CHO, 520 Kcal)
2. Using graph plot on Excel, draw a suitable graph to represent the data for
the two OGTT test results. Describe the responses to the oral glucose test.
(100 words)
At 0min (fasted) the OGTT for normal people is at 4.4 while for diabetic
people 7.2, whereas after 30 and 60min, the normal ogtt went up to 7.6
then 8.4 while the diabetic ogtt went up to 10.8 then 13.4. lastly, after
120minutes, the normal ogtt dropped to 6.2 while the diabetic ogtt
dropped slowly to 12.8.
Mean blood glucose (mmol/L)
OGTT test results
13,4
12,8
10,8
7,2
8,4
7,6
6,2
4,4
FASTED
30 MIN
60 MIN
120 MIN
time
OGTT, normal
OGTT, diabetes
3. Using the same graph, represent the data for the three GL meals. Attach
the generated graph to this document. What conclusions can be drawn?
(100 words)
Mean blood glucose (mmol/L)
OGTT test results
13,4
12,8
10,8
8,1
7,6
6,3
5,2
7,2
4,6
4,5
4,4
FASTED
30 MIN
8,4
7,3
6,2
4,8
6,3
6,2
5,5
4,5
60 MIN
120 MIN
time
OGTT, normal
OGTT, diabetes
HGL
MGL
LGL
According to the graph HGL has a faster uptake, but also drops faster than
MGL after 60minutes and stays at a higher 6.3 compared to MGL’s 5.5. This
could be due to HGL having a higher glycaemic load which stimulates a
stronger response and release of glucagon, which further elicits an insulin
response to balance the blood glucose levels.
4. Consider the following: how does the physical state of the meal (solid
vs. liquid, cooked vs. uncooked, high fibre vs. low fibre) affect
digestion and absorption rates (and hence postprandial blood glucose)?
(100 words)
Solid food is broken down through ingestion and chemically converted into
liquid whereas ingested liquid can skip this step suggesting that digestion
is faster for liquids. In terms of cooked food, carbs usually soften causing
them to digest faster in contrast with protein that hardens after cooking
and takes longer than raw meat. Fats also naturally slow digestion. High
fiber foods take longer to digest and absorb as it requires the breaking
down of polysaccharide linkages. As for postprandial blood glucose, foods
with a lower glycaemic index or foods that take longer to digest have a
lesser increase in BG levels as slow digesting food release sugar slowly.
5. What are the disadvantages to regularly consuming meals high in fat
and low in carbohydrates? (200 words)
High fat diets can cause a rise in cholesterol, specifically LDL due to most
foods having high amounts of saturated fats. Along with that, in some
diets such as keto diets, the consumption of fruits and vegetables is also
limited which can lead to nutrient deficiency as the body is deprived of
some vitamins and minerals such as fibre which result in a number of
bowel complications like constipation. Another risk of such meals is the
production of excess ketones by the breakdown of fats in the liver due to
short supply of glucose and over time can lead ketoacidosis which refers
to high levels of ketones making the blood more acidic and thus causing
dehydration. A low carb diet can also result in gluconeogenesis because of
shortage of glucose and glycogen which can not only hinder brain
functionality as its main source of energy is glucose, but also slow down
repair and function of other major organs which can manifest into physical
symptoms as lethargy, muscle weakness and nausea.
6. What is the function of fasting a minimum of 8 hours before an OGTT?
(50 words)
As the measurement at 0min (fasted) is used as a baseline for the test, it
is required that the blood contain none or minimal amounts of glucose to
prevent the reading coming out as hyperglycaemic. Furthermore, if there
is insulin in the blood that was released due to ingestion of glucose prior
to testing, it can cause the glucose to be absorbed in the cells which can
also lead to a false negative result.
Case Studies
CASE STUDY 1
A 55-year old woman reports of intense thirst and recurrent vaginal thrush
infections. On further questioning, she describes frequent trips to the toilet
and blurring of her vision.
A physical examination reveal a height of 5'3'' (1.60m), weight of 12 stone
9lbs (80kg), and blood pressure of 160/100mmHg (normal <140/90). A simple
"pin-prick" blood test reveals a random blood glucose of 17mmol/ L (normal <
11.1 mmol/ L).
A provisional diagnosis of type 2 diabetes is made.
1. Comment on the presenting symptoms, explain the physiological processes
that lead to their presentation in this patient. (100 words)
Since the blood is high in glucose, the kidneys filter out this glucose into the
urine which causes the water molecules to go down the concentration
gradient in the kidney and from the cell, which not only causes build-up of
fluids that leads to frequent urination but also ultimately dehydration. Along
with that high BG levels also lead to thrush, which is a yeast infection that
thrives in warm, moist areas of the body. Lastly, hyperglycaemia also affects
your vision as the lens inside the eye is swollen.
2. How would you interpret the physical examination and blood test?
(BMI = weight (kg)/height (m)2 Ideal 18.5 – 25; overweight 25 – 30; obese 30 – 40)
(100 words)
the patient has a BMI of 31.2 which falls under the obese range and can also
be a cause for the high blood pressure other than type 2 diabetes. The blood
test also shows increased levels of glucose which is a defining characteristic of
diabetes along with similar symptoms to those of type 2 diabetes.
3. If left untreated, this patient is at increased risk of which of the following
(circle all those that are appropriate):
nephropathy, hypoglycaemia, retinopathy, myocardial infarction, stroke,
neuropathy, diabetic ketoacidosis, muscle-wasting, hyperglycaemia, cold
intolerance, postural hypotension
4. How should this patient be managed? (100 words)
Some basic diabetes treatments include lifestyle changes such as exercise and
healthy eating which includes cutting back on refined carbs and calories and
adding fruits and vegetables to your diet along with more fibre. This would
also help in weight loss. For medications, drugs that either lower the level of
glucose by helping the body respond better/be more sensitive to insulin or
making more insulin should be used and may also include taking long lasting
insulin shots.
CASE STUDY 2
A 50-year old man reports of weight loss, despite increased appetite and more
frequent bowel movements over the recent weeks. His resting heart rate is
82bpm and blood pressure is 110/76. He complains of palpitations. The doctor
notices that there is also a slight bulging of the eyes and firmness around the
front of the neck.
1. What is your initial diagnosis?
Hyperthyroidism
2. Which symptoms are consistent with your diagnosis? Explain how these
symptoms arise. (100 words)
Hyperthyroidism is usually associated with high basal metabolic rate which
means that your body burns more energy due to which weight loss with a
high appetite is a common issue. Since thyroid hormones also influence the
heart, excess of this hormone can increase heart rate and fatigue. Not only
that but due to hyperthyroidism causing overactivity of the sympathetic
nervous system, the hyperstimulation leads to increased motility in the gut
thus causing diarrhoea. Lastly, the bulging of eyes is because of the immune
system attacking and damaging the tissues around the eye which causes an
inflammatory reaction whereas the firmness is due to the formation of
thyroid goitre.
3. Regarding your diagnosis, is this a primary or secondary endocrine disorder?
Explain your answer. (50 words)
since the patient has limited eye symptoms and a number of CVS
complications, it can be safe to conclude that it is secondary hyperthyroidism
as it usually affects middle aged people is the product of overstimulation of
the thyroid gland by excessive TSH in the circulation.
4. What would you expect the levels of T3, T4 and TSH to be in this patient?
The levels of all T3, T4 and TSH are elevated
Finally, in a second patient with a lack of iodine in the diet:
a) Thyroid hormones: high or low?
low
b) Is this hypothyroidism or hyperthyroidism?
hypothyroidism
c) Levels of TSH – low, normal or high?
low
d) Presence of a goitre?
Yes
Urine testing
The test results for 6 people (6 test samples including a control) are in the sheets
below, determine the common or major pathological cause (if appropriate).
Test sample 1- Normal
Observation of urine: Yellow, clear
Test results:
x
x
x
x
x
x
x
x
x
What is the purpose of this control (normal) urine sample in this
investigation?
It is used as a reference for comparison of values with the other samples
Test sample 2
Observation of urine: Yellow, clear
Test results:
x
x
x
x
x
x
x
x
x
x
Provide an explanation for the outcomes
Indicate a common or major pathological cause (where appropriate)
High glucose in urine due to hyperglycaemia as kidney filter out the glucose
from blood to urine.
Most likely an indicator of diabetes
Test sample 3
Observation of urine: Yellow, clear
Test results:
x
x
x
x
x
x
x
x
x
x
x
Provide an explanation for the outcomes
Indicate a common or major pathological cause (where appropriate)
Higher levels of ketones and glucose filtered out of the body by the kidney.
Could be due to ketoacidosis and diabetes as body is not able to absorb and metabolize
glucose thus causing it to burn down fat and produce ketones as an alternative. This
leads to excess ketones and glucose in the blood and then the urine which also lowers
the pH.
Test sample 4
Observation of urine: Light yellow, clear
Test results:
x
x
x
x
x
x
x
x
x
x
Provide an explanation for the outcomes
Indicate a common or major pathological cause (where appropriate)
Specific gravity measures the ability of the kidney to concentrate the urine
In this result the specific gravity is lower than normal, and the colour of urine is light
yellow and since water has a specific gravity of 1.000, the urine is very diluted. This
could be due to impaired kidney function due to the tubules being damaged, too much
fluid intake due to increased thirst, kidney failure or diabetes insipidus.
Test sample 5
Observation of urine: Yellow, slightly turbid
Test results:
x
x
x
x
x
x
x
x
x
x
Provide an explanation for the outcomes
Indicate a common or major pathological cause (where appropriate)
When the pH of urine is high, which in this case is 9.0 indicated that the urine is very
alkaline, it usually signifies gastric suctioning, kidney impairments, pyloric obstruction,
respiratory alkalosis or an UTI.The urine test shows a high number of leukocytes in
urine which could be due to an inflammation in the tract or kidney which is usually
caused by an UTI. Another result that points toward an UTI is the presence of nitrites
in urine as urine contains nitrates that are reduced to nitrites by the bacteria through a
nitrification process.
Test sample 6
Observation of urine: Yellow, turbid
Test results:
x
x
x
x
X
X
x
x
x
x
Provide an explanation for the outcomes
Indicate a common or major pathological cause (where appropriate)
This result shows turbidity in urine due to leakage of protein and blood in the urine
which could be due to insufficient filtering by the glomeruli in the kidney. This condition
is called proteinuria and can be attributed to several issues such as dehydration, high
blood pressure, diabetes mellitus, inflammation of the glomerulus, CKD, auto immune
disease or cancer. Haematuria refers to the presence of blood in the urine which can
also be caused by damaged glomerulus or tubules in the kidney and can happen due to
kidney diseases, infections, abnormalities or damage/trauma.
What are the advantages and disadvantages of the urine dipstick tests? (100
words)
The test allows for quick analysis of urine results for different factors such as
bilirubin, proteins, ketones, blood etc although these results could be a false
positive or negative due to the chemical reactions being affected by oxidizing,
reducing, and discolouring substances. This test can also be performed by
most people provided that they are not colour blinds and has no discomfort or
side effects plus can is reproducible. Though as mentioned before, the
accuracy of this test is questionable as it relies on the collection of the sample
by the patient and many of the abnormalities can be seen in normal people.