case study t1 Flashcards
(20 cards)
Which of these two conditions determines a greater loss of ECF
volume?
* Loss of 3L of water, but no loss of sodium from the extracellular space (pure
water loss)?
* Loss of 3L of isotonic saline from the plasma volume (equal loss of Na and
water)?
Step 1: know the difference
Difference between pure water loss and
isotonic fluid loss
* Loss of pure water from ECF,
➢increased ECF osmolality causes water
redistribution between ICF and ECF
* Loss of isotonic saline from ECF
➢No change in osmolality
➢No fluid shift from ICF
➢Volume loss is confined to ECF only
Step 2: determine how the body will compensate in the two
scenarios
First case: loss of pure water increases osmolality
* Vasopressin (ADH) response to change in osmolality
* Aldosterone response to reduced renal blood flow
Second case: loss of isotonic saline, no change in osmolality
* When volume is depleted to a certain level – large vasopressin (ADH)
response
* Aldosterone response to reduced renal blood flow
* These responses are delayed
Case study 1
Mr. K, 54-year-old male with Type 2 diabetes mellitus, poorly controlled, hyperlipidemia, history of
alcohol abuse.
Mr. K presented with mild fatigue and a general feeling of weakness. No confusion, seizures, or other
neurological symptoms. He reported no excessive fluid intake.
Lab Results:
Sodium (Na+): 125 mmol/L [133-146 mmol/L]
Serum Glucose: 10 mmol/L (elevated)
Total Cholesterol: 18 mmol/L (very high)
Serum Osmolality: 294 mmol/kg [275-295 mmol/kg]
What can you say about these values and what is your diagnosis?
Diagnosis: Pseudohyponatremia due to hyperlipidemia.
Key Takeaway: Pseudohyponatremia should be considered in patients with high serum lipids,
particularly if serum osmolality is normal.
Female patient of 58 years old has undergone major surgery a day and
a half ago and is receiving hypotonic fluid replacement.
The patient is alert, no other signs
The test results show:
Sodium 127 mmol/L [133-146 mmol/L]
All other tested values are within range
What is the likely cause of hyponatremia?
➢Dilutional hyponatremia
Case Study 3
Female patient of 86 years arrives at the emergency with signs of
confusion and extreme weakness. She lives alone with her family
visiting her every other day. They say she was fine and quite alert in
their last visit together.
Routine testing reveals
Plasma sodium concentration of 167 mmol/L [133-146 mmol/L]
Clinical examination: reduced skin turgor, low BP
Hypernatremia
Case study
A 58 year old patient has been admitted to the hospital with severe
abdominal pain that started in the morning. The patient does not take
any medication. The patient has low BP, and a distended and rigid
abdomen.
Blood gas test reveals:
pH 7.05,
[H+] 90 nmol/L,
pCO2 35 mm Hg,
[HCO3-] 19 mmol /L
What is your diagnosis?
Reference intervals:
pH 7.35-7.45
[H+] 35-45 nmol/L
[HCO3-] 22-28 mmol/L
PCO2 35-45 mm Hg
Metabolic acidosis
Case study
23 year old man arrives at ED as a result of a fall from a tree. Amongst
his injuries, he has a large number of broken ribs.
pH 7.24,
[H+] 59 nmol/L,
pCO2 59 mm Hg,
[HCO3-] 24.5 mmol /L
Step 1: check the hydrogen ion concentration
Step 2: check the levels of bicarbonates and PCO2
Step 3: what is your diagnosis and how would you treat?
Reference intervals:
pH 7.35-7.45
[H+] 35-45 nmol/L
[HCO3-] 22-28 mmol/L
PCO2 35-45 mm Hg
Respiratory acidosis
An infant is brought to the emergency: for the entire day he has been
vomiting consistently and the mother said that every episode starts
right after having breastfed the baby.
Blood gas testing reveals the following:
pH 7.56,
[H+] 27 nmol/L,
pCO2 45.5 mm Hg,
[HCO3-] 50 mmol /L
Reference intervals:
pH 7.35-7.45
[H+] 35-45 nmol/L
[HCO3-] 22-28 mmol/L
PCO2 35-45 mm Hg
Metabolic alkalosis
Case study
A young woman is about to undergo same day surgery. During the waiting
time, she becomes very anxious. Blood gases are drawn with the following
results.
pH 7.52,
[H+] 30 nmol/L,
pCO2 24 mm Hg,
[HCO3-] 21.0 mmol /L
She recovers quickly and the procedure goes ahead. What happened to her?
Respiratory alkalosis
54 year old male has been diagnosed with diabetes mellitus (DM), characterized by high
levels of glucose in the blood. The doctor orders an evaluation of the levels of albumin
in the urine.
Why?
➢Patients with DM have an increased risk of developing kidney disease
➢In the early stages of kidney disease we don’t see any signs of renal dysfunction
➢Typically, 7-10 years after DM onset the progressive damage to the glomeruli can
increase their permeability and small amounts of protein can be filtered→
albuminuria
➢Early detection of albuminuria can help us prevent the progression of kidney disease
You are on vacation with friends and having a great time. All of a sudden, a
friend of yours has abdominal pain and needs to urinate frequently. Your
friend says that each time they urinate they have pain and a burning feeling.
Knowing you took BIOCHEM 3H03, your friend asks for help.
You happen to have some urine test strips and they reveal the following:
Leukocytes (WBC): ++ (moderate)
RBC: moderate
Nitrite positive
All other parameters are within range
What do you suspect?
UTI
A 37 year old patient performs a routine urinalysis with the following results:
Specific gravity 1.010 (1.001-1.030)
pH 6 (5.0-8.0)
Protein NEGATIVE
Glucose NEGATIVE
Ketones NEGATIVE
RBC NEGATIVE
Nitrites NEGATIVE
WBC NEGATIVE
Bacteria SMALL PRESENCE
Yeast SMALL PRESENCE
What do you think of these results?
Bacteria, yeast: could indicate UTI or contamination of the sample
most likely contamination due to no nitrites and wbc and rbc
Case 1
28 year old patient sustained multiple injuries in
a motorcycle accident. Received blood
transfusions and underwent surgery.
Plasma values
Urea 21 mmol/L (2.5-7.8 mmol/L)
Creatinine 140 (50-110μmol/L)
GFR 58 mL/min (90-120 mL/min)
Osmolality 316 mmol/kg (275-295 mmol/kg)
Urine values
Sodium 5 mmol/L (20-30 mmol/L)
Osmolality 650 mmol/kg (275-295 mmol/kg)
Pre-renal feature:
➢in the blood→ urea increase is more significant than creatinine
➢in the urine→ little sodium and high osmolality (osmolality in the urine much higher
than plasma osmolality)
Case 2
28 year old patient sustained multiple
abdominal injuries in an accident. Received
blood transfusions and underwent surgery.
Three days later the following values were
recorded:
Plasma values
Urea 17 mmol/L (2.5-7.8 mmol/L)
Creatinine 225 (50-110μmol/L)
GFR 48 mL/min (90-120 mL/min)
Osmolality 316 mmol/kg (275-295 mmol/kg)
Urine values
Sodium 80 mmol/L (20-30 mmol/L)
Osmolality 324 mmol/kg (275-295 mmol/kg)
Intrinsic renal feature:
➢In the blood → plasma urea and creatinine increase in a similar way
➢in the urine → very high sodium concentration, urine and plasma osmolality are
similar
Case study 1
A 35 year old patient has been feeling unwell for two weeks. The patient
reports nausea, weakness, malaise. They noticed the presence of dark
coloured urine.
Plasma findings
AST 230 (8-33 IU/L)
ALT 305 (10-50 IU/L)
ALP 150 (44-147 IU/L)
GGT 25 (5-40 IU/L)
Bilirubin 30 (3-20 μmol/L)
What is your diagnosis?
Case study 1
Plasma findings
AST 230 (8-33 IU/L)
ALT 305 (10-50 IU/L)
ALP 150 (44-147 IU/L)
GGT 25 (5-40 IU/L)
Bilirubin 29 (3-20 μmol/L)
AST over 200 IU/L
ALT over 300 IU/L
Are a FEATURE OF ACUTE VIRAL
HEPATITIS
Typically, 5-8X the upper reference
limit (URL), sometimes can reach 10-
50X!!!
AST/ALT ratio is <1 in viral hepatitis
Case study 2
A 49 year old patient was feeling unwell (malaise, nausea) and was
admitted to the hospital with the following plasma findings:
AST 197 (8-33 IU/L)
ALT 95 (10-50 IU/L)
ALP 178 (44-147 IU/L)
GGT 75 (5-40 IU/L)
Bilirubin 22 (3-20 μmol/L)
Case study 2
A 49 year old patient was feeling unwell (malaise, nausea) and was
admitted to the hospital with the following plasma findings:
AST 197 (8-33 IU/L)
ALT 95 (10-50 IU/L)
ALP 178 (44-147 IU/L)
GGT 75 (5-40 IU/L)
Bilirubin 22 (3-20 μmol/L)
AST levels increase to a greater extent than ALT
levels (2-fold)
AST/ALT ratio >2 feature of alcohol-induced
hepatitis
ALP and GGT are typically elevated
AST and ALT are never over 10x the URL
In the world of clinical biochemistry how can you distinguish pre-renal AKI from intrinsic AKI?
Pre-renal aki
Pre-renal aki is the ability to concentrate or dilute urine by evaluating the levels of sodium in the urine and the osmolality of urine and compare it to that of plasma
If your urine or osmolality is higher than that of plasma typically twice as more
This means your urines are able to concentrate the urine so it is not an issue in the kidney
Intrinsic aki
Look at sodium which is typically higher than reference range because you are not able to reabsorb it
The osmolaity of urine is similar to that of plasma
This tells you that you are not able to concentrate
Levels of urea are also changing
A patient arrives at the ER and a blood gas test is performed.
pH 7.57 (7.35-7.45),
[H+] 20 nmol/L (35-45 nmol/L),
pCO2 17 mm Hg (35-45 mm Hg),
[HCO3-] 21.7 mmol /L (22-28 mmol/L)
What is your diagnosis? Show your reasoning
Respiratory alkalosis
Hydrogen ion concentration is below the reference range (assess first)
Pco2 and bicarbonate levels and between those two we want to see which one is affected in the most dramatic way (assess second)
For this particular once you took about the top two you can add my ph is confirming this but in real life don’t do it because irl your pH may not reflect this cases because your compensatory mechanisms may have already begun
You don’t have to worry about interventions
Causes are for you to understand but its to help you figure out in which cases but you don’t have to memorize those
Aki it would make sense to have a general idea about the causes
A 29 year old female goes to the family doctor because in the past 24 hours has been
experiencing an urge to urinate frequently (as if the bladder was never emptied properly) and
pain and burning sensation after urinating. The urinalysis shows the following results:
Specific gravity 1.010 (1.001-1.030)
pH 6.5 (5.0-8.0)
Protein NEGATIVE
Glucose NEGATIVE
Ketones NEGATIVE
RBC SMALL PRESENCE
Nitrites HIGH QUANTITY
WBC LARGE PRESENCE
Bacteria MODERATE PRESENCE
Yeast NEGATIVE
What is the most likely diagnosis? Show your reasoning
Uti
Presence of nitrate - which are byproducts of bacteria
Increase in wbc → therefore infection
Rbc → which might be directly related to hemorrhagic uti
Coupled all this and symptoms of the patient which is the irritation like symptoms that tell us this is a UTI
(sometimes if you do not have symptoms related to uti then it could be bladder cancer and there is additional tests (not in the test))
You need to mention there are bacteria whether they are moderate or high doesn’t matter you should mention it
Some bacteria inducing bleeding in the urine which is hemorgrpahic uti
A 55 year old patient forgot to fast before a routine blood draw and reports having had a
breakfast rich in carbohydrates. The medical examination shows no particular signs, and the
patient is doing great. The laboratory report shows the following values:
Glucose 9 mM (Fasting: 2.0-6.0 mM)
Bilirubin 7 μmol/L (3-20 μmol/L)
Total cholesterol 4.7 mmol/L (<5.18 mmol/L)
Creatinine 65 μmol/L (60-110 μmol/L)
Sodium 129 mmol/L (133-146 mmol/L)
Osmolality 296 mmol/kg (275-295 mol/kg)
What is the more likely cause of hyponatremia? Explain your reasoning
Pseudohyponanmetria
In case if you see this you would assume it is an indirect test
This is high glucose that increases osmolality
And if you look at sodium that is not a reflection of how it should be
The patient forgot to fast and has a high level of gluocuse because of high carb breakfast
And the patient is feeling fine therefore pseudohypoanmetria
But in hyperanmetria or electrolyte imbalance there are always symptoms
To be sure you can direct test → and chances are your sodium levels will be just as fine
If it was an actual hypoanmetria than osmolality would be low
Pseudohyponanmetria → high glucose and high cholesterol (i think)
A new diagnostic test has been tested in a population of 349 individuals.
* 310 test positive and have the disease
* 14 test positive but do not have the disease
* 6 test negative and do not have the disease
* 19 test negative but do have the disease
What is the sensitivity and specificity of this test?
Sensitivity 94.2
Specificity 30
This diagnostic test is good for screening because it has a high sensitivity
